Attack Analysis:
The goal of the Abele brothers has always been to determine what happened to the Grunion. Although some may disagree we feel that the evidence is strong enough that we have determined its location to at least make the next step in finding out what happened.
Below is the information we have about the attack. In light of our readership, particularly submariners, hopefully someone can help develop one or more viable hypothesis as to the demise of the Grunion.
It should be pointed out that there are some comments about the crew (shoddy construction, forgot to pull the firing pin) that should be taken with a grain of salt. There were major operational problems in the beginning of the war both with the torpedoes and with the subs themselves. To leave those comments out, in my opinion, would be a disservice to finding the truth.
There are three witnesses (diagrams and dialog) and a number of other bits of ancillary info.
Aiura: (Aiura was the military commander on the Kana Maru) Yutaka translating:
“The escort subchaser also came in and out the fog, at last we lost contact and the night came. KOANO MARU again went on alone in the foggy Bering sea toward KISKA. At July 30 08:00 we reached at the north of Kiska Is. about 20 nautical miles apart. But the dense fog prevented us to approach. We were forced to drifting and waiting the fog getting thin. The fog was getting thin for a moment and back to dense. We could do nothing but waiting. This day whole day the fog was dense and we were impatient. 15:30 A friendly seaplane fighter[Pete] ditched near us and we picked up. The plane and a pilot were both safe. The pilots were so young as just graduated his boy air school, similar age of my[S.AIURA] son. I was impressed with his figures that do his duty in the Northern sky. It was a happening that our ship saved him but I was so glad that we could help him. At the evening the fog still dense, we were alerting the enemy submarine attack. 17:15 We turned outside the open ocean, under 15 knots speed maneuvering zigzag course, decided to enter the KISKA harbor next morning.
July 31 Next early morning we again reached off KISKA harbor but the fog was still dense. We are drifting and waited. 04:40 The fog became a little thin and we can get our position by astronomical observation. We confirmed the altitude and latitude fixed the course toward the KISKA.
Enemy Torpedo Struck Home
05:15 We were avoiding the “MacArthur’s reef’ and at 158 degree 12 nautical miles distance of Segula Is. changed course toward 255 degree.
[*2] 05:47 “Torpedo! starboard fore!” Suddenly the signal master WAKISAKA first sergeant shouted. I saw two torpedo wake overlapped at I 00m starboard fore in the course crossing 45 degree with us, rapidly approaching. I at once ordered “Full turn starboard”. As KANO MARU went fast and the rudder turned much degree, the ship change the course rapidly toward right. I prayed the god and got tense for few second that was the most intolerable moment in my life. One torpedo wake passed after the stem we could avoid it, but other one hit the machinery room starboard side where was my back below and large explosion and sound occurred that was like a rumbling of the hell ground.
At the same time the main engine instead of its usual rhythmical sounds, but made two or three times of inertial dull movement and stopped. I was shocked by the force from the bottom and seized unconsciously the handrail and the base of compass. In a moment the machinery room was flooded whole, main engine lost power. We could not go anymore. Also generator, radio communication equipment and other auxiliary machines absolutely stopped. It was my disappointing but I had nothing to do.
The crews and soldiers seemed they did not feel fear at all and was vigorously preparing anti submarine combat or launch work of seaplane.
Lucky Dud Torpedo
This time we found a periscope of the submarine at very near right fore. Immediately 8em gun and 13mm machine gun started shooting. 8cm gun has less possibility to hit the submarine, but we thought the sounds of the gun was the only way to tell the KANO MARU’s crisis to the KISKA base. And also the 13mm machine gun fire were useless against the sub under the water but the splash aids the aim of 8cm gun crews. Further more the 8cm gun on the aft poop deck was malfunction by the heavy shock of torpedo explosion.
The periscope that had been right fore, gradually moved to right aft. 05:57 From the right 157 degree 300m distance the sub shot second salvo. One torpedo wake line from right aft passed below the ship bottom at about the bridge. It was no harm. How lucky we were I To transmit our crisis to the KISKA base, we planned as the last way to use the seaplane that we had picked up yesterday. The plane was still hooked under the derrick. The whole crews set the plane on the sea surface by only man power. The pilot, NMRASAWA the second class air soldier, tried much efforts but the engine never started so we had no way but accept the fate. The periscope sometimes appeared and moved from the stem to the portside. 06:07 From the left 135 degree very near the sub shot third salvo. Three torpedoes wake came toward us. Perhaps the sub shoot whole the rest torpedoes in the tubes and intended to finish us. I gave up whole, thinking the torpedoes must finish KANO NLARU and hard to breathe in more than ten seconds. Two torpedoes hit! but nothing happened! One torpedo struck the bridge fore, No.2 cargo hold. But unexpectedly it didn’t explode, lost its head and the rest body floated on the water tail down and about 0.5m part dry. Next one torpedo struck amidships portside, but also dud. Last one torpedo went away passing near ship stem. How lucky we are! I thank to the God protection.
06:10 Then we find the periscope at left 13 5 degree about 400m distance. Our forecastle 8cm gun and 13mm machine gun again started the fire. The sub kept the periscope up and moved calmly ignoring damaged KANO MARU. We clenched our fists but had no way to do. [*3] Then the sub seemed to begin to surface. The conning tower made ripple on the surface and the wave began washing the conning tower. I think the sub was unable to sink KANO MARU by the torpedo ( reload the stocked torpedo to the tube needs much minutes ) so finish KANO MARU by its gun or the sub thought KANO MARU could do no harm any more. Just then a 8cm gun shot hit the washing wave, made water column and dull water explosion sound. Also we saw the swell of heavy oil. All crews shout ‘BANZAI!’
Aiura: second source:
This day’s antisubmarine combat action aimed only the periscope so continued intermittently about 20 minutes. At last we found the periscope at left 135 degree about 400m distance, immediately start firing. The fourth shot that was the 84th counting from the first shot got directly the target.
About this submarine sink, later coming mine layer ISHIZAKI and other ships observed much oil spouting, piece of lifeguard buoy, chips that seemed to be the material of submarine decks, and other many things. They confirmed the sinking and radioed to the Fifth fleet and combined fleet chief of general staff through the fifth guard command. [*4]
More important info is about the torpedo. They, IJN Kiska base soldiers, took the rest of the torpedo which lost the head and floating near Kano Maru. They towed the torpedo body by boat to the Base, and observed. Aiura reported, apparently the head and body connection was irregular work. Because it seemed more than 30 bolts hole exists around the head-body connection part, but only three bolts were used and the rest was partial 10cm length silver-wax work not by welding.
Aiura said it is apparently not regular navy-yard work.
Aiura also reported, he thought the maneuver of the sub was strange. The sub seemed to have approach to the aft behind of Kano Maru shadowed from the forecastle deck gun, but is was too near to keep safe from the gun fire. Forepeak deck gun could at least bow or aft-end of the submarine. And Aiura said also it was strange 5 in 6 torpedoes were dud. 2 of them hit but not exploded. Aiura said the torpedo men must forgot the normal procedure to unlock safety pin.
Second Witness: RIKIMARU NAKAGAWA, ARMY Medical Sublieutenant
While I was looking aft on boat deck(port) in front of my cabin, I saw bubble running on the surface figuring half circle just 2 or 3 hundreds meters apart from shipside. I shouted ‘Must be Submarine!’ Then just at the head-end of bubble running, big black-brown water arose, something oily afloat on the surface, after a while a black thin bar appeared on the surface then fell down and submerged. I in spite of myself cried out ‘Good, You got what you deserved!’, and I am convinced the submarine was sunk by the shell. ”
Third Witness: was a “contract newspaper man” who visited the site after the attack.
WITNESS NOTE by KENJI HAMADA
I had got on a motor launch and left KANO MARU from portboard.
The boat ran over the stem and went to the starboard side of the ship.
Then I saw at left side of the boat, about 200m apart from my boat, that was 500m from KANO MARU’s stem, something was afloating on the surface. That were two cylinder, like oil drum, upright about 0.5m over the surface.
I found that objects but couldn’t approach so I didn’t understand what they were.
When my boat went on to the starboard and aft side of the KANO MARU, I saw the same two objects at the front of my boat, 50m distance, that was about 400-500m from the KANO MARU’s stern.
Again I didn’t understand what they were.
Later I saw a torpedo at land, that was without explosive warhead, picked up by the same(my) DAIHATSU boat.
Then I heard from Navy men (about the torpedo), and I understand what I had seen were torpedoes that lost its warhead and afloating upright.
SYOWA 17(1942) August 3rd PM 03:30
Army contract newspaperman
KENJI HAMADA
Kenji provided a sketch. Two copies are provided each with slightly different annotation
Few submariners think that a 3 in shell that hits the wake caused by the conning tower would sink a Gato class sub. However we must consider the proximity of the 84th shot and “dull water explosion” Whatever happened was in some way amplified by the shot. Most submariners are aware of the poor quality of the MK 14 torpedoes. They pre-exploded, would run low, did not detonate upon contact and occasionally would circle around. In addition the submarine batteries were subject to explosions and fires. The exterior torpedo doors were closed manually and such things as a displaced gasket would be devastating.
It also should be noted that the sub did not implode / explode which would have happened if the compartments had been closed off. This tends to imply that what ever happened was rather sudden.
On the slide path there appears to be some debris, some fairly large, and about 25 ft of the bow of the sub appears to be buried or blown off.
Was there some comments saying that one of the torpedoes may have looped around and hit the sub? Is it also possible that there may have been an accident in the bow torpedo compartment? (Ala the Kursk)
Could it be that somehow a torpedo exploded either in the tube or out of it and heavily damaged the bow and/or other compartments and opening it to the sea? Being bow heavy, and with possibly one or more compartments damaged or flooded, the captain would have tried to surface imho. With the sub negative bouyancy, a hit or two from the ship shelling the sub could have caused flooding that may have been too much to counteract and would have sent it to the bottom with no hope to surface. The weakened bow may have snapped off on impact or may be still there buried in the sediment not visible to the sonar.
It may not be likely or even probable, but may explain why it sank so fast. Hopefully once they get some footage from the site we can find out.
If the debris indeed included torpedo bodies, then it would imply a catastrophic explosion in either the forward or aft torpedo rooms. Since the torpedoes would have been crushed at a depth of more than several hundred feet, the torpedo room must have vented to the sea above the rated depth of the hull. The bubble path suggests that the boat turned on its axis as it sank, and the rush of fuel to the surface inside the path indicates bunker rupture as the boat exceeded crush depth. Perhaps one of the reloads had a “hot run” which would have served to arm the warshot, with a consequent shock detonating the warshot on the rack.
True, just doing a little mental thinking on possibilities on what may have happened. Won’t really know much till they get a look at the wreck itself. The fact that the wreck looks reasonably intact seems to suggest that it was open to the sea near the surface or it would most likely have imploded as it reached crush depth and would be in numerous pieces on the bottom.
Reasoning that something catastrophic happened onboard is plausible as it’s hard to believe just a shell hit or two from the ship would have been enough to sink the Grunion that fast. Always the chance for a million in one lucky hit, but still hard to believe all the same.
I’m not sure how this fits into the information given here but I came across copies of several pages out of a book that I not no the title. The top of the page just says Trigger. Anyway, the information was written by someone who received a transmission from the Grunion and it says, ” FROM GRUNION X ATTACKED TWO DESTROYERS OFF KISKA HARBOR X NIGHT PERISCOPE SUBMERGED X RESULTS INDEFINATE BELIEVE ONE SANK ONE DAMAGED X MINOR DAMAGE FROM COUNTERATTACK TWO HOURS LATER X ALL TORPEDOES EXPENDED AFT… He went on to say that this the last transmission by the Grunion. The interesting part is what he says in the next paragraph. ” Years later I read an account of an interview with a Japanese sub skipper, now master of an American-owned merchant ship operating out of Yokohama. As skipper of the I-25 he had made three patrols from Japan to California. On one return trip, when passing the Aleutions, he had torpedoed a surfaced submarine. The date he gave was July 30, 1942, which tallied exactly with our interception of Grunion’s last transmission.”
Does this account agree or contradict the information gathered so far?
Hi!
Clay Blair reports (in SILENT VICTORY) the following:
“Patrolling of Kiska on July 15, Abele attacked a destroyer, firing three torpedoes which missed. Later that same day he attacked three ships he believed to be destroyers. [Rear Admiral] English credited Abele with sinking three destroyers, but postwar analysis showed they were patrol craft of about 300 tons each, only two of which sank. On July 28, GRUNION attacked an unidentified ship, fired two torpedoes, and missed. On July 30 off Kiska, Abele reported heavy antisubmarine activity and said he had ten torpedoes remaining. Colclough ordered him back to Dutch Harbor.
“Nothing more was heard from GRUNION. She disappeared without a trace, like SHARK.*
“* Some believed she had been sunk by a Japanese submarine, I-25, which reported sinking a submarine in the area. Subsequently it was learned that I-25 sank a Russian submarine, one of four en route from Vladivostok to Mare Island for a lend-lease overhaul.”
Hi!
The translation says “the wave began washing the conning tower” and then says “Just then a 8cm gun shot hit the washing wave, made water column and dull water explosion sound. Also we saw the swell of heavy oil.”
If the “washing wave” was the wave “washing the conning tower” then the shot that “hit the washing wave” may have hit and exploded in the conning tower or some nearby part of the submarine, causing enough damage for the Japanese to see “the swell of heavy oil,” but I suspect the submarine was only damaged and not destroyed.
The key appears to be eyewitness Rikimaru Nakagawa, who observed the “bubble running on the surface figuring half circle just 2 or 3 hundreds meters apart from shipside” followed by “at the head-end of bubble running, big black-brown water arose, something oily afloat on the surface, after a while a black thin bar appeared on the surface then fell down and submerged.”
FWIW, Mr. Nakagawa’s testimony appears to describe a circular-running torpedo returning to hit Grunion: the steam-powered Mk XIV torpedoes then in use certainly left a trail of bubbles, circular runs were known to occur with this type early in the war, and the”big black-brown water arose” is consistent with an underwater torpedo detonation.
Examination of the wreck may be more conclusive, but based on this witness I would say we can hazard a fair guess that Grunion became frustrated with torpedo failures and attempted a surface engagement, was hit causing minor damage, and then resubmerged and went back to torpedoes, one of which circled back and sank Grunion.
I spent a few days last week with Russ Dieselberg [My Uncle and Uncle of L.H. Doell Jr R2C ] .in atlanta last week. also had lunch with Rhonda Raye in Cartersville Ga. This Info is really interesting. There are so many things coming to surface over this discovery, that are changing many lives.
Thanks for the E mail from my step cousin Nancy Springer. Hope to hear from you soon. I am doing some local research on the biography of Junior Doell.
JIM LUCAS
I think I can shed some light on why the After Battery Room hatch is open.
GRUNION had a single gun mounted aft of the conning tower.
http://www.navsource.org/archives/08/0821602.jpg
If, after having the dud torpedoes, GRUNION decided to surface and finish off KANO MARU with her gun, then the gun crew would have formed up in the crew’s mess, directly under this hatch, and would have even likely loosened the dogs in preparation for throwing it open to man the gun.
OK, if the After Battery Room “scuttle” was loosened in preparations for surface attack. Could the 3″ shell have hit a high pressure tank in the pump room ( located, I believe just ahead of the contol room - conning towers washing wave) blowing the scuttle open and thus allowing a very fast flooding of the center of the ship?
When the boat is submerged for any time period the internal pressure can build up (from a variety of causes, chiefly venting compressed air) to a point where the overall pressure inside the pressure hull is slightly in excess of atmospheric pressure. In a normal surfaceing evolution the upper conning tower hatch is opened first (normally it is the ONLY hatch opened). This is done by ‘cracking’ or slacking the hatch dogs off a small amount before actually surfaceing the boat. When the conning tower hatch breaks surface the higher internal pressure acting on the hatch causes it to spring open against the slackened ‘dogs’, which keep the hatch from slamming open during the time it takes to equalize with sea pressure. When this happenes there is a voice report made “Hatch is Cracked” it can take several seconds to equalize this pressure, at that time the hatch wheel is fully opened. There is also a single manually operated spring loaded ‘catch’ which must be pushed aside to allow free movement of the spring assisted hatch to the open position. There can be quite a lot of energy built up at this point and an over eager quartermaster could be lifted off his feet if he acted too soon.
It is possible that if a gun crew were standing by in the mess room for a surface gun action that the upper hatch dogs may have been prepared for surfaceing in this fashion. I don’t think they would ever have been fully backed off or retracted to the full open position.
An other matter here is that Gato class boats (at least later) were equiped with a second hatch assembley that bolted on the flanged hatch combing inside the compartment. These secondary hatch assembleys were fitted for war patrols as protection against depth charges or other explosions (or collisions) which could effect the actual deck hatch or hatch seals. This secondary hatch plate was equiped with an oblong personnel access hatch also held in place with a ’strong back’ type of hatch dog. Travel up and down through this 2nd access hatch was not easy or quick. I don’t know if the ROV got a look down that hatch or not, it would be interesting to see what condition this secondary hatch was in.
The portable hand rail shown to be in position outboard of the deck hatch was normally ’stored for sea’ as a routine. It is possible that it was left in position to assist the speedy deployment of a surface gun crew through this hatch.
Grunion’s sister ship, the USS Growler, sustained heavy bow damage when it rammed a small Japanese freighter in February of 2003. It would take some force to blow it off although a premature torpedo explosion, either in the forward room or just after firing or even from a circular run may be sufficient, if not a direct hit, to render such damage. The late Richard H. O’Kane, himself a survivor of a circular run in October of 1944 on the USS Tang, wrote of such a theoretical possibility, the damage from which might have resulted in the ultimate demise of the USS Wahoo. Coincidentally, the Wahoo was recently found in La Perouse Strait, where it was sunk.
Error correction…the USS Growler rammed the Japanese freighter on February 7, 1943 and not in 2003.
Error correction…the USS Growler rammed the Japanese freighter on February 7, 1943, and not in 2003.
As a former diesel submariner, it seems entirely plausible to me that a shell hit in the conning tower would cause the lower CT hatch to malform, allowing the flooding CT to also flood the control room below.
While a fleet boat could certainly deal with a flooded CT, it could never survive a flooded CT and Control Room and would settle towards the bottom, eventually imploding any sealed off compartments.
The few photos seen seem to support that hypothesis, with the relatively intact conning tower structure and sail. I’m anxious to see more photos of the remaining hull structure of the submarine, but based on the AB hatch being open, it appears that section may not be crushed either and possibly flooded before reaching crush depth.
It is also possible, based on the missing bow, that she suffered a circular torpedo hit, or had a detonation in a tube. It’s interesting that the massive damage only extends to the fwd edge of the FTR escape compartment, meaning that the back half of the torpedo room was not shredded.
I believe that if Gruion came up bow first;deliberately using this maneuver to speed a surface action. The bow was mistaken for the conning tower. The 13mm shell could have thus penetrated the forward torpedo room and exploded detonating one or more of the torpedos there. Thus, promptly sinking the USS Grunion and explaining the missing bow, open hatches and unusual manuvering, bubble path as the after gun was to face the target., Bubbles came from partiallt opened hatch.
Grunion had earlier reported that it had ten torpedos remaining on board. For the sake of arugument I am assuming this was six tube loaded in forward torpedo room and four tube loaded in after torpedo room.
I believe the third ’salvo’ (firing position at 0607 hour) were fired from the after torpedo room. Note that Kana Maru was dead in the water and not moving forward. The attack ‘angle on the bow’ was Port 135 degrees (a better ‘aspect’ angle than the other two attacks).
The ‘gyro angle’ manually set into the three MK 14-3 torpedos would have been very close to each other as very little ’spread’ was required to lead the nearly stationary target.
These weapons were fired from very ‘close aboard’ something in the order of 300 to 400 meters-yards. The MK 6 exploder in the MK 14-3 Torpedo had a fixed ‘enableing distance’ that the torpedo had to travel through the water before all of the internal exploder components were in a physical position to allow the train of initiation charges to cause a contact dentonation. I have been unable to find out exactly what that distance was (Com Sub Pac could tell us that is they get interested in this) but this could account for the two ‘dud’s altho there were other known problems with this exploder. This element may have had an effect on the second firing position (0557 hour) in which a single torpedo appeared to ‘run deep’ and elcewise failed.
The third salvo has witnessed two ‘dud’ hits about where they were supposed to hit. The third weapon opens to the right and passes behind the target. This could easily be the start of a ‘circular run’. The rudder control (steering) of MK 14-3 is a phenmatic servo which has three positions, right full rudder / left full rudder / or neutral (center). The rudder control is not graduated in small increments. It corrects torpedo path by very fast movements to full left or right or middle settings. It receives its instructions from a mechanical device that senses the gyro position during the run to target.
USS Tang SS 306 was a victim of a circular run with eye witness survived. The reports estimated approx 20 seconds after firing the torpedo came full left circle and hit after torpedo room and flooded after three compartments.
If Grunion fired the last three weapons from the after torpedo room her heading at time of firing would have been approx 135 degree compass. I think that immediatly after firing the Grunion made a hard left turn, increased speed (to assist with trim control) and tried to come to heading of something 080 degree which would have opened the target, hidden or shadowed from the over active 8CM gun on target bow, and allowed another firing solution for the remaining (largely useless) torpedos.
Having just (1) fired three torpedos of approx 3,000 lbs each from the stern, (2) increased speed and (3) made a hard rudder movement her ‘fine trim’ and ability to maintain 63′-67 ‘foot periscope depth was temporarly compromised. The stern planesman was (reasonably) unable to control the angle of the boat and as a result the sail ‘broached’. (Exposing her Port Side) Certainly not the first time this particular trim-control problem has happened. Grunion had a rough heading of 045 degree compass at this point. It appears to have nearly completed her turn to left (port).
And then the circular running last torpedo impacted the forward torpedo room. This accounts for the “head end of bubble running” and “big black-brown water arose” and “dull water explosion” and “bubble running on surface figuring half circle” (eye witness account Rikimaru Nakagawa, from Kana Maru main deck level).
I cannot envision how a 8 CM (roughly 3 inch) cannon shell could do all of this damage. I think that a good look at the video from the ROV will show the damage from the shell. It will be interesting what the Navy will have to say. The scandalous ‘MK 14 Torpedo PROBLEM’ is not yet lost in Navy Submarine memory. (or the USS Scopion for that matter) If I were a Weapons Officer in Com Sub Pac today I would already have run a few computor simulations just to see..? Even if it wasn’t a circular run, the Grunion sank because the Torpedos didn’t function correctly. The second firing position should have finished the short fight. There are officially only two USN boats (USS Tang SS 306 and USS Tullibee SS 284) known to be sank by circular runs. Confirmed because credable eye witnesses survived. There are other cases where doubt remains…Grunion is most certainly one of them.
I served as a Torpedoman on Gato class boats in late 1960’s and remember firing ‘excersise’ shots with MK 14-5. We always rigged the ship very carefully during these firings, the Mk14 (in high speed setting) travels at 47 knots and at +3,000 lbs. nobody wanted to get hit by one even if it didn’t have a war head.
Hi,
I´m new to this blog, but as a submariner I think I agree with Pat Householder. The CT hat is completely deformed outwards, this can only be the consequence of an explosive force within the CT. Wether this came form the 8cm hit or an internal explosion somewhere else I can´t ascertain. Remember Kursk: the torpedo compartment was literally missing but the rest of the hull looked intact… but in the inside several pressure tight bulkheads had been destroyed.
If such an exposion (in the torpedo room) had taken place, it could have spread aft, blowing open the CR to CT hatch and then deformed the CT-bridge hatch, at the same time blowing open the “cracked hatch” aft.
So far, it´s only speculation, at least until an image can be obtained of the conning tower at the supposed shell hit point .
Fascinating story. Iread “Blind Man’s Bluff” this stuff is even more interesting! God rest their souls.
Kevin Kelleher, Big Sky MT.
The suggestion that the ‘Torpedo Room’ neglected/forgot to ‘pull the firing pin’ is not credible ; when those fish were loaded they were iready for the job they were designed to do - that is, once they have come up to firing depth and the impeller on the exploder has completed the required number of revolutions to arm it. {Of course, this was early in the war, July,1942, when many of our boats were having problems with faulty torpedoes.) It is interesting to read the comments that have been proffered as an explanation of Grunion’s last moments. As more information is forth-comming based on pictures we have not yet seen, perhaps that annalysis will give us more definitive answers to our questions. Bob Sands, TM2/C, USS Paddle (SS263)
“The portable hand rail shown to be in position outboard of the deck hatch was normally ’stored for sea’ as a routine. It is possible that it was left in position to assist the speedy deployment of a surface gun crew through this hatch.”
Photos of the USS LAGARTO wreck also show this hand rail lying on the deck (deck planking rotted away) atop the hatch.
Ed Walson, what a great post!
Thanks for the Footage Bruce, all is well with it.
Ill send you a copy this weekend of what we did with it.
I noticed that the Mine Layer ‘Ishizaki’ reported ‘observed much oil spouting, piece of lifeguard buoy, chips that seemed…to come from sumarine decks’. This ‘lifeguard buoy’ must be one of the two ‘Salvage Buoy’ systems carried on Grunion. These two buoys (approx. 4-5 foot diameter) were carried recessed and faired into the superstructure of the main deck just forward and to the port side of the two torpedo room main deck hatches.
The buoys had a length of wire cable connecting them to a wish bone or ‘bail’ attachment to the torpedo room hatches. If the boat were disabled in shallow enough water (200-250 feet) that rescue were possible, this buoy could be released by use of a hand hydraulic pump located in each torpedo room. The buoy would float to the surface, the wire would pay out from a friction drum and ultimately the buoy was conected to the upper torpedo room hatch. This wire could be used by the ASR (Auxillary Submarine Rescue) Divers in various ways to assist rescue or salvage efforts of the boat.
The point is that these Buoys carried information on an ingraved plate which indentified the submarine by name and hull number and gave other instructions to whoever discovered the buoy. This probably is where the Japanese acquired the name and hull number of the Grunion to start with! When Gato class boats made patrols in the 1960’s these buoys were typically welded down so that adverse sea conditons or other accidental means would not allow them to deploy at an inconvenient time.
Also note the presence of this buoy in the oil and other wreckage at that location indicates that the the deck and superstructure forward of the forward torpedo room were destroyed at that time. Not from contact with the ‘underwater volcano’ on descent, or while sliding down the submerged slope.
I believe this makes an additional case for the ‘circular run’ torpedo theory.
This comment is for Ed Walson. Ed would you please contact Bruce directly at mbable@rcn.com. Thanks.
Sorry, Bruce’s email is mbabele@rcn.com.
I’m a little confused by Aiura’s Torpedo Analysis Diagram, specifically the dashed line indicating a bubble path since the firing of the first salvo. Could this be a misinterpetation, or was there really a bubble path since the first salvo? I thought Aiura’s statements suggested sub tracking by Periscope sightings only. If there was a bubble path coincident with the sub’s location after the first salvo, that could indicate flooding or a stuck tube hot run.
I very much tend to agree with Ed Walson’s senario as a likely cause for the sinking from the evidence we’ve seen so far. There were several other reports of ‘circular runs’ during the war besides those of Tang and Tullibee. Both Tang and Tullibee were on the surface when they experienced their problems, but other skippers reported circular runs while submerged. As the Mk. 14’s were later determined to run at least 10 feet deeper than set, a submerged boat faces the same danger, depending on how deep the fish were set. At that time of the war the policy was to set the torpedos to run beneath the target, so it is easily possible for a deeper than set torpedo to strike the firing boat when it is submerged at 60′ to 65′ periscope depth. The ‘bubble path’ can easily fit a torpedo wake and one of the few things I can think of that might create a similar wake would be if one of the shots from the Kano Maru had holed the main induction, however this would not result in the eye witness account of “head end of bubble running” and “big black-brown water arose” and “dull water explosion”. It would also make sense that the fish were fired from the after room, as the arc of the circle would most likely intersect the bow. Both Tang and Tullibee were sunk by torpedos fired from the forward room, and struck in the stern.
At this point it appears to me that Grunion fired torpedos, one of which made a circular run and struck the bow in the Forward Torpedo Room just forward of the escape trunk. Additional support for this theory would be the evidence of, or lack thereof, implosion damage to the FTR. The pictures posted so far indicate to my eye, extensive implosion damage to other parts of the boat. The ATR seems to show this just forward of the aft capstan; the Conning Tower definately shows it; and the open After Battery hatch indicates it. As with the Scorpion, it become a matter of “if” and “then”. IF a torpedo struck the FTR and no water tight doors forward of the After Battery were closed, THEN then hatch could have been blown open by the pressure wave of the explosion. IF one or more of the water tight doors were closed, THEN the collapse of the bulkhead between the Forward Battery and Control, or more likely, the one between Control and AB, would cause a resulting pressure wave and could blow open the hatch. Whether or not Grunion was fitted with hatch ‘doublers’ at this time of the war, I do not know.
Ed makes a very valid point. When and if it is finally determined what ‘event’ sank Grunion, the ’cause’ was the defective Mk. 14 torpedo.
David Decrevel
SS-328 SS-396
Past Nat’l Historian USSVI
To Doug Sego. I looked at the sketch provided by Aiura and concluded that whoever interpreted the sketchs and other after action reports added the ‘red’ numbers 1 thru 6 which I.D. the individual torpedo firings AND the ‘path of bubbles’ with the arrow. Aiura narritve was very experianced, factual and ’seaman-like’ with vessel positions, correct angles on bow (from the elevated view point of Maru bridge) and specific times but did not mention the bubble track. Aiura did not make any guesses only facts which were probably copied into his vessel log book. I disregarded the red ‘path of bubble’ note, it came from a different witness (the non-seaman medical officer (at main deck level) and was added in by one translater or another.
Open hatch pics.
Isn’t that the hatch rubber seal/gasket shown in the pics? It’s been looped completely around both the hatch and the outer hatch deck cover. Only a limited number of ways that could have happened.
To Bob. I also believe it is the hatch gasket. It appears to be the correct shape and dimension, with hard, straight edges, and is a continuous circle. The hatch gaskets that I recall, were flat on the 3 sides that fit into the channel of the hatch, and the outer, or seating side, was in the shape of a triangle. As the decking is attached to the hatch, the gasket would merely have to ‘roll’ out of its’ channel and loop over the decking. This further supports the idea that the hatch was closed, and was subsequently blown open. If it was open, I can’t forsee any force that would cause the gasket to come out of the channel.
For Ed Walson
The last message from Grunion dated on the day they were lost stated that they had 10 torpedoes left, none in the after room. Bruce, can you post the last message on this site? In the encounter with Kano Maru, two different spreads of 3 torpedoes each were fired. After these 2 salvoes there was probably a reload activity in the Forward Torpedo Room, to load the remaining 4 torpedoes.
I have followed the search for the Grunion with great interest since its inception. I have no special knolwedge of submarines, but I am a professional historian with much experience of working with primary documents in foreign languages. Knowing well how even subtle mistranslations can lead to major errors of interpretation, I suggest that the Japanese documents so critical to understanding the Grunion’s fate be re-translated by a professional translater and checked by a second. The English renderings we have are so obviously awkward that there is room for doubting whether they convey the meaning of the Japanese originals as clearly as they might.
All, ‘The Captain Beech’ (himself) when communications officer on Trirgger intercepted a garbled message from Grunion (and personally knew the wardroom officers of Grunion) states that torpedos aft were expended. So all of this torpedo action takes place from Tubes Forward. Starting the day with six tubes loaded and four on storage skids.
At 0607 she fires spread of three from some distance (?) appox 135 degrees (target angle on port bow). Kana Maru is dead in the water, stationary target. Gyro angle of these weapons would have been very close togeather to effect a spread (say 5-10 degress max. separate). Grunion was firing at ‘Center of Mass’. Two of weapons hit where they are aimed (no. 2 hold & midships) duds. Third torpedo (sixth of the day) passes astern of Kana Maru. I have run some very rusty geometry on this. Assumed Kana Maru to be in the order of 600 feet long and a distance to target of 400 yards. This shows the sixth torpedo to open something in the order of 15-25 degrees in the 400 yard run distance. This MK 14 was acting erraically from the git-go. Projecting this out shows a very large diameter circlular run of approx. (using my assumptions) of 3.6 minutes.
None of my figures are accurate but proportionally they fit togeather. There was a 630 lb. war head going somewhere…in the same time period the Grunion had her bow removed by an explosion of this magnatude. What is the likelyhood that it was another separate event?
Gunion as submerged has near zero buoyancy (proably diving officer has her trimmed to be slightly negative to prevent accidental ‘broach’). Point of Gravity (or fore and aft balance) is in Control Room. Over all trim is slightly rough (witness the single broach) due to maneuvers (hard turn) and tropedo firing activity forward.
Torpedo dentonates near/at forward torpedo room, breeches hull integrity of fwd room and I believe the forward battery compartment. All the heavy gear forward of forward room hatch falls away. (Forward bulkhead of Main Ballast Tank #1 is visable in photos of bow). This is six torpedo tubes, bow planes and associated hydraulic rams and motor, anchor and chain, forward capstan, structure of WRT and Bow Buoyancy all separate from the ship.
Point of Gravity moves aft to some where around the after engine room or maneuvering room. The breeched forward battery compartment causes immediate electical failure leading to propulsion failure. The ‘hole in the water’ or bubble effect of the explosives caused all vessel forward motion thru water to cease. The boat settles by the stern and pivots to its new balance or trim points. Witness (non-seamen Medical Officer) mentions ‘black bar fell over’. This probably was the fully extented periscope as the boat slowly rotated and settled astern. This pivot also allows some fuel oil to excape throught the open ballast tank bottoms. But depending on the actual angle of the boat not all of the oil was lost, the oil remaining may have had an effect on the descent speed.
I believe that the After Battery hatch was ’sucked’ open by the expanding lower pressure ‘bubble’ created after the initial ‘’high pressure” hydraulic wave passed over. The After Battery compartment shows the same signs of collapse as the remaining compartments in the stern. I conclue that the ‘doubler hatches’ were indeed installed, and this event on the ABH did not allow flooding of the compartment.
Gunion settled to the seabed stern first. Landed (bent rudder first) on a sloped seabed and slid down hill to her resting place. Drag marks or slide trail caused by the propellers and stern planes. It appears that the bow section did not scoop up much bottom material because the stern remained much heavier through out.
Regarding the third salvo as reported by witness:
“One torpedo struck the bridge fore, No.2 cargo hold. But unexpectedly it didn’t explode, lost its head and the rest body floated on the water tail down and about 0.5m part dry. Next one torpedo struck amidships portside, but also dud. Last one torpedo went away passing near ship stem.”
The ‘stem’ is the bow or a ship. Reviewing the available picture of Kano Maru, it is difficult to determine if the bridge is forward, or aft of ‘amidships’, but if the translation is accurate, I would surmise that Grunion’s torpedo spread was stern to bow, and not vice versa.
Ed…
“Doubler Hatches” were a later war development as someone posted previously. For example; USS BATFISH didn’t receive them until her refit over the period of 01 Dec 44-30 Dec 44.
Refit item; “Installation of safety plates for deck hatches”
http://www.ussbatfish.com/patrol-6.html
I’d disagree with your scenario only in minor details however;
I have serious doubts that an external low pressure bubble would shatter the After Battery hatch locking mechanism as it is. My view; it’d take a sharp, violent force to do so…from the inside. Bottomline; two of the locking rods are snapped, and the third is deformed. You can also see the stainless steel liner that was around the inner lip of the hatch was stripped away and wrapped around the ladder (outward).
If you enhance various photos of GRUNION wreck, you can see the curvature of the AB compartment “top” in pretty much the correct plane from the rear of the conning tower to the deck gun. I’m not totally convinced that it imploded. I suspect it’s a possibility that the Control Room and AB compartment forward bulkheads failed sequentially. Possibly one or both were damaged/weakened by the forward explosion. Which would also explain the catastrophic failure of the AB hatch locking mechanism (unless I got ripped off when I bought my diploma from the “Jethro Bodine Internet School of Fluid Mechanics”).
Cons against this argument; (1) It sure looks imploded. (2) If you lay the photos out in a mosaic against a diagram of a Gato class sub, the “high” points in the wreckage all correspond with internal compartment bulkheads. (3) Compartments aft of the AB compartment are all definitely imploded.
Pros; (1) As stated. (2) Still working on that. (3) Compartments aft of the AB compartment are all definitely imploded. Shockwave generated by collapsing forward compartment bulkheads vented through AB hatch, which was not designed to defeat a massive internal over-pressure/hydrostatic event. Bulkheads/hatches were, and held long enough for the compartment to implode.
If GRUNION impacted stern first, how’d the cavity in the bow get “dished in”? I’m totally baffled. And if it hit bow first, why didn’t the MBT #1 and the torp drain tank get smashed in?
Ed….was wondering if you would crank up your rusty geometry one more time, and see what difference (if any) might show up IF the spread was from aft to forward. If the 6th fish passed the bow instead of the stern would it make any difference? Also, remembering back to your TM days, what was the arming distance of the MK 14? My memory cells seem to recall 450 yards, but then I did spend way too much time in the battery wells.
Bob, I never completed the curriculum for “Jethro Bodine Internet School of Torpedo Explosive Forces”, but do agree that IF such an event did occur in the bow, the chances are quite good that at least the watertight door/bulkhead flappers between the forward room and Forward Battery would be damaged; not too sure about the ones between Forward Battery and Control. Like you, I do believe that the After Battery hatch was ‘blown’ from the inside. If the hatch trunks on Grunion were the same as the ones I’m familiar with, the stainless steel trunk liner covered the entire inside trunk surface. It would take considerable force to separate and deform the liner.
IF there was a circular run, Grunion knew about it, and would immediately maneuver to avoid and sound the collision alarm. I can easily recall how fast doors and bulkhead flappers got closed when that alarm was sounded! I think it’s fairly safe to say, that IF that is what happened with Grunion, all the watertight doors and bulkhead flappers were closed.
One general question has been on my mind, and its answer could give some hints on the sequence of damage. At what depth did Grunion strike bottom and start its’ slide down the slope? Above hydrostatic collapse depth, or below? According to Rear Admiral Andrew McKee “All the model tests indicated Grouper” (SS-214) “would fail at 550 feet at the deepest”. Although some skippers of Gatos reported going deeper than that, it is a ‘starting point’.
Speaking of low pressure bubbles, here’s an idea that Jethro didn’t cover; If the control room/AB bulkheads collapsed/imploded violently, and vented via the AB hatch…could this account for the dished/”pinched in” bow? The weakened plating getting “sucked” into the remains of the Forward torpedo room/FB compartment?
A couple of e-mails exchanged with Bruce and some of the last posts have convinced me that the AB hatch was blown open during the boat´s implosion. It seems that we all agree by now that the sinking was caused by an explosion in the FTR.
But Bob´s last paragraph in his last post is most puzzling, and regarding the boat´s “attitude” when hitting the bottom I think that Ed Walson´s post about shiftin Center of Gravity deserves a much closer view. If someone has Naval Engineering qualifications, and the stability crossed curves for this class of sub, we might figure out where the COG was after the FTR was blown apart. But we must remember that at the same time water rushed into the forward part of the boat, in part compensating the COG some distance forward again.
Furthermore, the stern compartments are imploded, which means they were still dry so this section was light in comparison.
Now allow me to relate the assumption of a light stern to the “pinched bow” effect.
We have assumed the FTR was severed from the rest of the hull by an explosion, but what if not? I recall the story of a sub that fired twelve torpedoes at an oiler, all of which hit but none of which exploded. The skipper observed in every case a spout of water. This was caused by the compressed air tank of the torpedoes exploding. Could this have been the case on Grunnion? Where there any oil tanks around the FTR that would account for the “black water” even if the torpedo didn´t explode?
If you think this might be possible, then we have a bow heavy submarine with an uncontrolable flood. On its way to the bottom it passes crushing depth, bulkheads collapse and a hatch is blown open. The damaged bow hits the bottom and bends upwards. If you do this with a tube of paper you´ll see creases appear where the material is compressed. If this happend to Grunnion´s hull, this resistance failure coupled wiht external pressure would bend the steel inwards. Except in the bottom, near the keel, where the steel would not be compressed but stressed. In the bow pictures the bottom doesn´t look pinched (as far as I can see, but me eyesight is not that good).
Contrary to the dead stop Ed described (as in this scenario we don´t have an explosion) Grunnion still has a forward motion, either by inertia from her lost propulsion or by her free fall to the bottom. With her bow burried in the mud, the hull breaks where the creaes appeared and finally lands on the silt (bending the rudder, that´s clearly a bend caused by an upward, not lateral force), sliding down to its present position.
I think when this thing happens (a haevy body sliding down a slope made of soft material) a small landslide occurs, so the marks along the path are not made by the hull, but are scars left by portions of the bottom when moving downslope. Can someone check Robert Ballard´s book on the finding of the Bismarck? If I recall well he describes this phenomenon in it.
I´m sure this reasoning has some weak point or another, but at least it´s new and may spark a few ideas. I´ll be more than glad to hear your comments.
Bob, I think there´s a simple answer to your question, wether Grunion hit stern or bow first.
The main question we´re trying to answer here is: why did Grunion sank? If you ask people like us you´ll get answers like the ones we´re proposing. But ask a naval engineer and he´ll say: Archimedes! It sank because it´s weight was greater than the lift provided by the water it displaced. In other words, ships float or sink as the result of interaction between two forces: weiight and lift. In our particular case:
The stern compartmets are imploded, so they were dry and rushing water had no access to them until the implosion.
Whether the FTR was still attached to the hull or not is irrelevant. Although the Center of Gravity would have shifted aft in case the fore end had been severed (as Ed Walson correctly points out) that´s only one of the forces involved. What happened with lift? Just as the COG is the point were weight is applied, there is a point were the lift is applied: the center of buyoancy. In a surface vessel, any distance between the two centers in the longitudinal way will produce a trim, with which the COB changes until it is aligned with the COG. Submerged submarines, however, have no longitudinal stability, no change in trim will produce a change in the postion of the COB. That is why fore-at personell movements are restricted and when they occur the diving officer has to compensate them.
When the forward compartments were flooded this center of buoyancy moved aft, to the dry compartments that were the only parts of the submarine still providing some displacement and lift. Imagine a cutaway drawing of the boat, paint the flooded compartments blue and the COB must be near the center of the white (dry) compartments, well towards the stern. The COG, however, could not have travelled so far. even if it had gone into the forward engine room. The final result is a lift force applied further aft than the weight, and that means a down bubble.
Guido, From rusty memory…the COG (Gravity) and COB (Buoyancy) on SURFACED Gato boats were about 16 foot different (perpendicular) and centered on Control Room, which Engineering-wise also was the center of NEGATIVE TANK (an important tank). In fact I would guess that negative tank was located at this point for this reason. ie; Flooding negative tank would simply take to boat down, with-out otherwise upsetting the Formal Trim.
This is a principle that all ‘proper’ ships have: ie; COB is above COG at all times, distance between POINTS depending on vessel burden. During Diving or Submerging of any submarine (which are not proper ships) the COG and COB change places. The two POINTS change places vertically, and when the two points are at the same (or pass the same) elevation the vessel is extremely unstable. ie. A large wave at this ‘moment’ could cause a large Pitch or Roll or both. Not likely, but this ‘physical point’ is a very real moment in time and has assocciated RISK. This is why Diesel Boats in-general rode-out big storms on the surface rather than submerged. There was/is a certain hazard to the Surface-Surface-Surface evolution.
Grunion during this attack was at Battle Stations, ie: all Water Tight Doors were closed and dogged (maybe not all ventilation ducts and their flappers). She had a GOG, but it was very dynamic. There are provisions in fthe sequence of firing a 3,000 lbs. torpedo wherein the weight of the explused torpedo is compensated for by taking-in (retention of) the sea-water which displaced the volume of the fired torpedo…but it is not weight perfect. The Diving Officer and Trim Manfold Operator have to ‘pump and flood’ additional water into-out-of the Trim Tanks in order to fully compensate to a ‘FINE’ Trim. This is a time consuming activity due to the pumping rate (GPM) of the trim pum + over coming sea pressure. The Diving Officer probably started the attack at a ‘Negative Buoyancy’ (of +1,000 lbs. or so overall) so that in effect, the forward motion of the boat, with water flowing over the bow and stern planes, tended to ‘hold’ the boat at periscope depth.This is the only ‘LIFT’ inherent in a submerged submaine. This trim would was a common practice (depending or sea conditions) and helped to prevent to biggest NO-NO of all, which is ‘Broach’ of the sail or shears.
So…POB is several feet below the keel (Grunion at this point is not a proper SHIP and has zero buoyancy or less). POG (simple balance) is not Fine Trim, but Compromised Trim (work in progress-due to 6 x 3,000 lb. Torpedos expended in 20 minutes & and a hard turn for course correction). Explosion at Forward Torpedo Room…Grunion losses several thousand pounds of weight from bow balance component more or less instantaniously. This causes a large ‘UP’ bubble, from which she never recovers.
The unflooded compartments at this point provide some displacement of weight, but this displacement is not siqnificant compared to over all weight and distribution.
A factor in this scenario is the remaining fuel oil. Assuming a ’settled’ angle of something in the order near perpendicular (180 degree), not all of the fuel is lost from the ‘free flooding’ FBT fuel ballast tanks. Diecil fuel is roughly 80% of specific gravity of seawater, and remaining fuel in otherwise undamaged FBT would have effected the overall keel angle (and velocity) of the boat during descent.
The ‘big black brown bubble arose’ eye witness account: the colors are inherent in the chemistry of the exposive.
Archimedies (287 BC) is the Patron Saint of Submariners and Divers as he originated all of the volume and surface area ‘numbers’ used by ComSubPac to solve these type of questions.
I have some comments reserved for COMSUBPAC which I will post later.
Ed
Of possible bearing on the discussion, and for what it’s worth, from Jethro’s “Internet School of Photo Analysis” (Dave, shame on you for neglecting your edication);
(1) What appears to be “recent” wreckage from the continuing collapse of the conning tower is lying to the port (as should be given wrecks orientation).
(2) What appears to be the bridge cowling (portholes) and ladders lying across the center/starboard side of the conning tower, BEHIND the periscope shears, to the starboard. This can be seen most clearly without enhancement in pic “Open hatch 22″. Cowling is “face downward” with l(what appears to be) adders etc. on top of it. NOTE: GRUNION is lying head down with an incline to port.
(3) What appears to be the RDF mast has fallen forward across this wreckage (possible fishing net/line tangled in top?).
(4) What appears to be a glass port from the bridge cowling is lying on the deck adjacent to the AB hatch.
(5) What appears to be wreckage from the conning tower (from the size and the attached mounting braces) is also tangled with the deck gun base (pics are really bad, but my best WAG is part of it is plating from the shears).
(6) The deck gun is angled astern, and is at full elevation. What kind of force (and/or orientation) would required to break the travel lock and pitch the barrel into this position?
(7) Periscope shears are bent moderately to the forward and port. Bend increases toward the top. Currently appear to be separating from the conning tower and are going to collapse forward/port. “Original” bend doesn’t appear to be from deterioration of the wreck.
Bow; Looking at the pics (I’ve been concentrating aft), it appears the bow separated from the bottom upward and went over the upper port quarter. This would account for the (few) jagged metal edges angled upward/port, dished plating on the starboard edges, and even more pronounced dishing to the port, i.e. the “squished paper towel roll” effect. You can actually see on the starboard edges where the metal was “stretched”. It doesn’t appear that this was the actual point of impact/explosion because of the relatively “clean” edges, but where the weakened hull failed, possibly because the hull was more rigid at this point (due to the escape trunk mounting?). The actual point of explosion appears to have been low on the port quarter (pushed in plating), somewhere forward of the break. If you examine the pics of the break closely, the hull has been pushed upward and starboard from this point, and deformed inward. I think this is independent of the bow section separating.
If GRUNION had an explosion/torp hit forward, weakening the hull (obviously) at this point, what would be the effect (on the damaged bow) of her forward speed, attitude, bow plane orientation, and the weight forward, given what details we know?
To summarize;
(1) I don’t think the hull forward of the break “vaporized” or fell off immediately. I think it got corkscrewed off relatively quickly, in the descent, or less likely, on impact. I’d specuate that not only did the GRUNION suffer a circular run, but possibly had one of the few instances where the magnetic exploder worked (more or less) as advertised.
Ed,
First I´must appoligize if I sounded too self-confident in any of the paragraphs of my previous post. Second, I am also a submariner, so I know all the stability problems associated with diving and firing torpedoes. But as I am not American and Spanish being my mother language, I may have used the wrong words to describe the “lift” of a ship. I believe you are speaking about the “dynamic lift” provided by the diving planes, while I was speaking about the “static lift” provided by the water displaced by the submarine´s volume.
What I meant for “lift” is the force resulting from the weight of the water displaced by the hull. The point where this force is applied is always, if I´m right, somewhere within the submerged portion of the hull. If a surface ship alters its trim the shape of the submerged hull changes and so the position of the COB shifts. In a submerged submarine whichever the bubble is, the shape of the submerged hull doesn´t change so the COB remains stationary. Even when a submerged submarine has near zero bouyancy, this means that there is a force almost equal to the sub´s weight applied in the opposite direction, and its point of application must be somewhere in the hull, otherewise the said force would have no effect in it and it would sink.
However, if Grunnion´s bow was severed the shape of the hull did change and so did the position of the COB, which moved aft. At the same time, there was a loss of weight at the bow, which made the COG travel aft too, how far we would need an engineer to make the calculations. From the pictures I hope you´ll agree with me that the aftermost compartments are collapsed, whereas the forward ones are not (except for the conning tower). This would mean that the flooded portion of the forward part of what remained of the hull was providing only weight, not compensated by any significant displacement of water (only the thickness of the steel plates would displace any). That is why I am convinced that Grunion sank bow first (or at least must have hit the bottom in this position).
Regarding the “black water” I was only speculating here. I have seen the explosion of a torpedo running at 25ft with an equivalent explosive charge of 460kg (920lbs) of TNT and the black water rose to at least 150ft. That´s why I wanted to propose the “dud torpedo” scenario, I thought that such a geiser would have been described more accurately by the witnesses, that´s all. And I also would have expected such an explosion to have blown open the FTR watertight door and allowed for the flooding of the control room at least.
But I believe you may be remebering something wrong. During diving process, COG goes down as a result of the ballast water filling the tanks from below, and at the same time the COB goes up as a result of a larger portion of the hull being submerged (the subs I´m used to have only fore and aft tanks, not saddle ones, but I´m almost sure it must work in the same way). “Free surface” effect while the ballast tanks are partially filled further decrese this difference in height between the two points. This effect dissapears when the tanks are completely full. But the points never change postions. COB remains always above COG. Just picture the cross section of the sub with both points and a string attached to each: pull downwards from COG´s string and upwards from COB´s. If COG is above COB, the opposed forces will turn the sub upside down, until the nullify each other. On the contrary, if COB is above COG the submarine will always right itself. Unlike surface ships, submerged submarines have a stability range of 180°, they would always end upright.
It would be most interesting if someone could make the calculations required to determine how far bach did the COG and the COB travelled. Hopefully the data required will be somewhere among the mass of plans that apparently are available.
Speaking of over-confidence; I’ve started to take a close look at the pics of the forward section of GRUNION.
I’m now pretty sure (but not confident) the Forward Battery compartment imploded. Violently, as per the center line compression described previously by Ed. The effect is much more pronounced/noticable in the after compartments, likely because the hull (and compartments) were much narrower.
I think the bulkhead between the Forward Battery room and the Forward Torpedo room is either gone, or flattened forward almost to the escape trunk, to include the reloading hatch…the available pics don’t show that area well. But it appears to be choked solid with debris. I haven’t been able to ID the top of the FB compartment at all, or ID any of the debris other than some of the deck fittings and sub-deck piping. The “compression damage” stops at the break of the conning tower, more or less where the FBR/CR bulkhead was located.
I’ll take a rain check (for once) on rushing to any conclusions…
In response to David’s observation that maybe Aiura used the term ‘Stem’ correctly and meant ‘Bow’ as regards the last three torpedoes. The question was ‘If the spread was aft to forward’. I looked at that with even more rusty Trig ability. The problem is ‘Target Forward Speed’. This input to the TDC is basic to the TDC’s recommended Gyro Angle for Torpedo Course. I am purely guessing that it can accept a target forward speed of something between maybe 40 knots down to 0 knots but it needs to be a positive number (assume zero to be positive). This kept me awake for two nights and in the end I still don’t know how or why Fire Control Tracking Party would (or could) set up a spread from stern to bow. I think they would do it the same way they always did it, nothing new under those conditions.
However I plotted it out and found that it certainly would be possible for that miserable
6th torpedo to make a circular run to its left or port.
Note: My accumulated information on MK 16 Exploder mechanical enable range is several references to 450 yards and one reference to 450 rotations of the impeller wheel. Assume one rotation is one yard of travel? I no longer even consider that Grunion was too close when they fired. Practically impossible. The 4th and 5th torpedoes were duds. In my plots I assumed a minimum track of 500 yards.
I assumed Kano Maru to be 200 yards long. Spread was fired at 10-15 second intervals with gyro angle 4 degree between shots at the target (this allows approx 50 yards apart at impact). Torpedo 4th and 5th impacted more or less where they were aimed.
If Torpedo 6th ran circular to its Right it was appox 11 degrees off target at 500 yards, passing 50 yards astern of Kanu Maru.
If Torpedo 6th ran circular to its Left it was approx 22 degrees off target at 500 yards and passed 50 yards to STEM (bow) of Kanu Maru.
A perfect circle (in the case of the Left circular run) from the firing point (intersected approx 50 yards astern of target) worked out (not surprisingly) to be 1000 yards in diameter and 3,140 yards in Circumference. Torpedo run time at 47 knots 1.98 minutes or 1::58 secs.
I still like the idea (David’s post of 4 Oct. noted “possibility…there were fish remaining aft” ) that this was a stern shot. What happens next is possible in the two minute time frame.
Note: I don’t think Grunion was aware of the circular run, they would have flooded negative and went deep.
If this was a Stern Shot, Grunion (according to the general sketch from Aiura) and Grunion was more or less stern-on to the target (at 147 degree heading, at guesstimated speed of 3 knots, she turned hard to port and came to approx 050 degree compass. (A course change of something like 100 degrees) I don’t know what Grunion turn radius was but in 2 minutes at 3 knots she travels over 200 yards square into the perfect circle.
Note: There is a pretty good case for Bob’s comment on 8 Oct. that “the magnetic exploder worked (more or less) as advertised”. Thats my work-in-progress.
I noted two other places in Aiura’s Narrative that he used the term ‘Stem’.
(1) ‘saw two torpedo wake overlapped at 100 meter starboard fore’ ‘crossing 45 degree with us’. He takes evasive action of starboard rudder and the ship responds (coming more parrelell with the torpedo wake). (2) “one torpedo passed after the STEM, we could avoid it…but other one hit machine room starboard”.
I think he clearly meant STERN here but a couple of other questions are raised. It takes MK 14 at high speed (47 knots) about 4 seconds to cover the distance. Clearly not time enough to make rudder movements. If the figure here were 1000 yards the time increases to to about 38 seconds, which at his probable speed of 15 knots may have been time to alter his course to actually avoid the aftermost torpedo.
However the comment ‘torpedo wake overlapped’ make me wonder if the 1st torpedo fired that morning wasn’t also trying to run to left of target. Almost like ’so whats new?.
(2) After the 3rd Torpedo fired from Starboard 157 angle on the bow (the single shot which ran deep) Aiura’s statement “the periscope sometimes appeared and moved from the STEM to portside”. The sketch indicates that Grunion passed astern of the target to the port side for the final set-up. I think he meant stern here or the interpreter simply got it wrong.
So while the starting numbers are wild, when this is drawn out it fits together pretty neatly.
Ed, sorry to have cost you 2 nights sleep with my WAG, but look at the bright side, you got to use your rusty mathematics again. Bob was correct in chiding my neglecting my education, but I did graduate first in my class in Jethro’s “School of Wild A** Guesses”.
Speaking of mathematics, John Hart and I were talking and he suggested I do a ‘plot’ to ‘guesstimate’ Grunion’s movements. I came up with some things that matched what you say regarding the first shots. Working from the charts and diagrams by Aiura, and using the usual submarine plotting tools commonly found around the house, I came up with the following: (partial excerpts)
Kano Maru Speed Estimate:
Working from Aiura’s ‘chart’ drawing, I estimate the position at 0515 to be 52 deg 9′ 25″ N, 178 deg 5′ 25″ E. At what I assume is the 0547 position (circle in center of circle) estimated position is 52 deg 07′ 20″ N, 177 deg 52′ 15″ E. From the 0515 position the extreme northeastern tip of Segula Island bears 158T, at 7.66 nautical miles. Course from 0515 position to 0547 position is 255T. Distance from 0515 position to 0547 position is 8.34 nautical miles estimated. The distance traveled in 32 minutes makes the speed 14.36 knots. If I do the plot using the 0515 position and the 0544 position, estimated to be 52 deg 07′ 10″ N, 177 deg 53′ 45″ E, the distance traveled from 0515 to 0544 is 7.53 nautical miles on a course of 252T, in 29 minutes, for a estimated speed of 15.579 knots. The estimate of distance between 0544 and 0547 positions is approximately .81 nautical miles. At 15.5 knots one could go exactly .81 nautical miles in 3 minutes.
First Salvo:
At 0547, Kano Maru, on a course of 255T, sighted torpedoes at 100 m, coming in at 045 relative, or from approximately 300 degrees T. Mathematically, at a high-speed setting of 46 knots, the torpedo would take only 4.23 seconds to run 100 meters. At a low speed setting of 31.5 knots it would take only 6.179 seconds to run 100 meters. If observation is correct as to distance (100m), then Kano Maru had insufficient time to execute a turn, and one torpedo simply ‘missed’ aft. If the distance observation is incorrect, or mistranslated, and Kano Maru avoided one torpedo by turning, she could have turned no more than approximately 35 degrees to about 290T in order for one fish to miss aft and a second to strike, probably aft of amidships. (The exact location of the ‘machinery room starboard’ unknown, but from Aiura’s drawing it is indicated aft of amidships). Any turn further than about 35 degrees would have likely made the 2nd fish miss astern as well. This is, of course, dependent on Kano Maru’s actual speed, and rate of turn.
As you note Ed, one fish of the first salvo might also have been ‘erratic’. Comes down to exactly what Aiura meant by ‘overlapped’ I suppose. For the purposes of my plot I estimated Kano Maru to be a length of 443’ (Katsuragi Maru Class), and I used a shooting range for Grunion of 800 yards.
This obviously brings us no closer to what actually caused Grunion’s demise, but like Ed, it exercised my rusty mathematics skills.
With continuing research through various sources I have found these reports of circular run MK 14 torpedoes, including the two previously mentioned.
11 April 1942 Seadragon SS-194
“At 1720, she fired three torpedoes. Twenty-nine seconds later the first torpedo exploded halfway to the target. The second torpedo broached and circled abeam of the target. The destroyer avoided the third torpedo. Seadragon changed course and went to 200 feet to avoid the circling torpedo and the expected depth charging.”
7 March 1943 Triton SS-201
“One of her torpedoes made a circular run which forced her to go deep.”
23 March 1943 Whale SS-239
“Whale fired a fourth torpedo which ran “hot, straight and normal”—for one minute, then circled, heading back in the direction of Whale. “We went to 120 feet and prayed”, the commanding officer later reported. The erratic torpedo changed its mind after reaching Whale’s beam and headed back for the freighter, finally exploding.”
9 June 1945 Tinosa SS-283
“Sound reports torpedo making circular run! Can hear screws plainly as torpedo, set at six feet in depth, passes close overhead with screaming whine. FLOOD NEGATIVE! TAKE HER DEEP.” (I can’t ascertain if this particular event was a MK14 or MK18.)
Ed,
I´m sorry to admit that I can understand little of your technical description of a spread firing, but if what I understood (regarding the 3rd salvo and positive speed imput for the TDC) I must agree with you that there´s no reason for the Fire Control Tracking Party to do anything different than usual. The only possiblity would be that the CO mistappreciated the Target´s Angle on the Bow by 180°, something uthinkable of in this case.
Just as evreybody here I believe in a circular run, at leat there´s no photographic evidence of a shell hit anywhere (unless it hit the bridge,which is missing, but in that case it didn´t compromise any part of the pressure hull and so played no part in the sinking) and I have read with great interest your posts about your “manual simulation” of the torpedo tracks. Out of sheer ignorance about Mk14s I´d like to ask you a couple of questions:
Was there any “straight run” right after the torpedo was launched and before the exploder was armed? (modern ones have it, it´s intended to keep them from homing in the sub´s own noise)
I believe you´ve done your simulations with the fast speed setting, would that be the most likely speed chosen against a stationary target?
If you think the answers are a little off this blog´s aim please feel free to contact me at gsambucetti@yahoo.com.
And now a couple of questions for the audience in general:
Are there any records about the changes of speed and course after the torpedoes were fired in Wahoo and Tang? Maybe if they could be examined they could shed some lignt on this case.
And the BIG ONE (for me at least, if it´s been ansered before please forgive me):
There were two torpedoes fired in the first attack: one hit and exploded, one missed and should have sunk at the end of run.
One torpedo on the second attack which ran deep, missed and should have sunk at the end of run.
Three torpedoes in the third and last attack, two hit and were duds, third missed and possibly hit Grunion.
That gives a total of two duds, two missed and sunk, and (possibly) two hits: six in all.
But Kenji Hamada clearly states that he observed FOUR torpedo bodies floating: two would be those of the last two duds, they were even close to each other as one would expect of two things that stopped at about the same place. But where on earth did the other two come from?
In the first place I doubt that the body of an exploded torpedo would survive and even less in a floating condition. But even if you grant that, what are the chances of the first hit and the last torpedo bodies float side by side after 20mins action?
Could there have been more than six torpedos fired? Could any dud have gone unobserved in the excitment of the moment?
I hope I won´t keep anybody awake with this.
Guido, With MK 11 Mod 3 there was no straight run to distance the weapon from firing vessel. It may have run relatively straight untill the steam turbine got up to full RPM and the gyro scope got up to very high RPM. Steering engines were powered by High Pressure air flask. Rudder controls were influenced by turbine RPM for the gyro position sensing mechanism somehow (I think). MK 6 exploder was (my mis-use of the term ENABLE) fully armed at a through water travel distance of approx 450 yards by rotation of an impeller wheel located in bottom of war head (in the exploder cavity). This wheel required to rotate 481 revolutions (approx 450 yards ?) which mechanically raised the thumb sized, very high explosive ‘initiator’ up and into the cavity of coffee cup shape and sized ‘tetryl booster’ which was inside the HBX war head. The spinning impeller also charged the electical capacitor which provided the electrical charge neccessary IF all other conditions allowed a dentonation.
My quick and dirty looks at firing geometry didn’t look at different speeds as direction and possible turning radius were my objective. However, I think they would have all been hi speed shots because slower speed would give the target more time for evasive action, which Kanu Maru may have actually accomplished at the first action.
Kenji Hamada, Contract Newspaperman saw torpedos #4 and #5 in two different places, while his small boat traveled around the Kanu Maru. The expanded torpedos with 630 lbs war heads broken off and steam engines now flooded would float in this attitude because the High Pressure air flask was in the main body of the topedo housing to supply buoyancy.
David, I’ll show you mine if you’ll show me yours. Contact me edwardrwalson@yahoo.com and I’ll send PDF of my scratch pads. You may try to see if you can tinker with Grunion position and turning circle given the choice of bow or stern firing position for the last salvo. My rough sketch answers OK for a stern shot and a 110* turn to port but gets more complex for a bow shot. Laying it out in plot with estimated Grunion speed and known length should be a piece of cake.
I assumed Kano Maru at 15 knots on the morning because of his mention of that speed two or three days earlier when he lost his escort and was headed back out to deep water in the fog. I figured that after he got his morning star shot and knew where he actually was (first time in three or four days) that he headed for the barn as fast and directly as possible. I think his signalmans first observation (shots #1 & #2) must have been at 1000 yards.
I think his various reported estimates of distance over water are off (short) by at least 30%. The Grunion did not fire #3 or #4-#5-#6 from outside of exploder arming range (450 yards). When I did my rough calcs and boat positions his reported 8 CM shell (angle-direction from his sketch) surprised me with an intersection on my estimated possible Grunion position and scaled out at 600 yards not reported estimate of 400 yards and this intersection was based on Grunion firing the last rounds at 500 yards. I think even 500 yards is too close but then I only stay at the Holiday Inn sometimes.
I just noticed the hypothesis of the sinking located at http://www.navsource.org/archives/08/08216e.htm
A few comments; I think it’s highly unlikely that water pressure stripped the remaining foward decking and took the forward fairwater/bridge structure plating with it. The fairwater is designed to be “free flowing”, and more than one boat came home with sections of the decking stripped. The (some of the) main deck supports can be seen in the debris atop the the FB compartment, as well as what appears to be the (bent) forward radio mast and associated fittings. In this scenario, these would have been amongst the first things carried away…long before the fairwater. Yet they are still (more or less) where they should be. If I had to guess, my money would be that something fairly substantial struck the bridge, demolishing it and bending the shears in the process. Most likely the bow or debris from the bow when it separated.
Speaking of the shears, and “black rods falling over”…where’s the attack scope? The search scope is shown housed, but the attack scope isn’t shown in any of the pics (that I’ve seen). Whether it’s housed, snapped off, or still extended could be a useful fact.
Also, the deck gun is most definitely reasonably upright, pointing at max elevation, and located where it should be. Canted somewhat rearward to the bow, but this is because of the distortion/break to the hull. The gun is mounted roughly over the AB room/forward engine room bulkhead, and is mounted to a fairly substantial reinforced platform fixed to the main hull IIRC…the bulkhead areas have (reasonably) kept their original form. Photo “2nd sighting port side 26″ shows this fairly clearly, without examining the other photos. However, if you look at the other pics showing detail, you can clearly see that the elevation gear/cog is all the way forward. Compare against the pics found here; http://www.navweaps.com/Weapons/WNUS_3-50_mk10-22_pics.htm
One theory to consider; The damaged bow and flooded forward torpedo room (if still attached) would have put GRUNION into a steep head down attitude during initial decent. Once it separated, losing the weight forward, the GRUNION corrected somewhat to a more “keel down” orientation, but still in an uncontrollable “dive”. Given the extremely steep slope of the bottom, struck stern first, then pogoed forward, impacting onto her starboard bow. Finally settling with weight to the stern, and slid down the slope. Something for everyone…lateral damage to the rudder, dishing in the starboard bow (but not crushing it), compression/impact cracks to the hull forward and aft, the “undamaged” front of MB#1 etc.
Guido;
“Was there any “straight run” right after the torpedo was launched”
I think after the torpedo is fired there was a straight run called the “reach”, before the gyro angle kicked in and put it on track to the target.
David,
I don´t think that the 100m distance is correct, either by missappreciation or by incorrect translation. Imagine yourself as the Captain on a day with visibility reduced by fog when suddenly someone cries out “Torpedo”. You spend 1 sec trying to figure out if you heard correctly, then why me, another second looking out to see by yourself, a third shouting an order to the helmsman who instantaneously obeys you, and that leaves only one second for the rudder to move and for the ship to start turning. Impossible.
On the other hand 1000m seems to me too far away (especially if you´re assuming a firing distance of 800yds), you would need to be quite high above the waterline to see the wakes at that distance. Don´t know what the bridge height was in KANO MARU.
I believe the first torpedo just missed aft. The overlapping wakes indicate an erratic run, but Aiura doesn´t say if he was hit by the straight wake or the overlapping one. It is possible at this stage (first attack) that Cdr. Abele misscalculated the target´s speed. You used 15.5 knots in your calculations, any skipper with a good sailor´s eye would go either for 15 or 16, and that would be enough for a close miss. If the speed chosen was 15, then the torpedoes would have missed astern, unless one of them ran erratically and had a small deviation to the right. That one would hit.
About the torpedo speed setting we would need to know what where the “default” settings for this type of target, probably there was a CO manual that would have been hammered into every CO´s brain during his training. War was only six months old and probably not enough experience had been yet obtained to allow skippers to deviate from their training proceedures without facing severe reprimand on return.
And t
David, just found this on Google:
Kano Maru, length between perpendiculars 137m (about 425ft) 6940 t, 17knots cruising speed, 18.7 max. Are you figuring out her speed from “fixes” on a chart? That would give you “speed over ground” or true speed, but not speed over water, and that would be the one used for the fiiring control solution.
Do you have information on the currents and the wind condition at the time of the attack. The positions of the two pairs of torpedo bodies I don´t think it is possible they are the same, they couldn´t have drifted 1100yds (or any distance, actually) form bow to stern faster than the boat form which Hamada sighted them.
Ed,
Thanks for the explanation on the workings of the exploder and it´s arming process.
Regarding the torpedo´s speed, different speeds will yield different turning radiuses, just as they do for ships. Maybe it´s worth trying them and see what comes up. Most surely the first salvo was set at high speed but once the target had been disabled there was no need for this.
About Kenji Hamada´s sightings, they keep puzzling me. At first I thought they were the same pair sighted twice, but then I thought why would they drift in a different way than KANO MARU? They shouldn´t have changed relative positions, unless there was some significant wind that made KANO MARU drift more than the torpedoes: they would drift with the current alone.
But furthermore, if Kenji saw them first off the bows and then off the stern, what means that they had drifted to that position faster than his boat, for they were already there for him to spot when he arrived. He says he saw “same two objects”, but then again, there would be no exterior differences with which to identify them, especially when he says that he saw the first pair at about 200m and couldn´t approach. I think I´ll try my cinematics and see what I can figure out.
Unfortunately (for our particular interest) KANO MARU was sunk a few days later by air attack so it was never docked, and we´ll never know how many torpedo warheads she had in her belly.
If this helps your attack plots;
KANO MARU is listed (has her own entry) in the USN 1942 Recognition Manual (O.N.I. 208-J), (which GRUNION would have had) with stats that agree with those listed in Lloyds. Includes pictures, a diagram, and mast/kingpost heights.
Engines amidships, and appears to have 3 hatch covers forward, 3 aft.
Tonnage; (gross) 8572 / (D.W.) 9731