In the latter half of 1964, the Irex sustained damage to her “chin” sonar array and had to head for the marine railway for repairs. Here is Tom Hand's MM3 (SS) account of the ensuing adventure.
We were hauled soon afterward into the lower sub base marine railway to fix the sonar.
The scuttlebutt I heard after the fact of why the marine railway broke is the railway operator hauled the boat up at the wrong speed and in doing so stretching the chains. Since the Irex had the Guppy II conversion which added significantly to the weight is what I heard the operator hadn't taken into account. Secondly the rail locks were not physically inspected to insure that they were engaged properly by the operators before they left for the day. Since the chains had stretched and the track lock pins were not engaged, the weight of the boat and the marine railway cart all sat on the chains which all broke a few hours later (anyway that's the scuttlebutt I heard about why it happened)
I was one of the people working under the boat on the marine railway cart when the chains broke and the cart and boat took off into the river.
Here's what I remember (keep in mind this all happened in a matter of maybe 30 to 45 seconds).
While we were under the boat in between keel blocks attaching salt water cooling hose flanges and hoses to the A/C sea-water supply, we heard a rapid series of “clank, clank, clank, clank” like a sledge hammer hitting a large steel beam repeatedly. We couldn't see from where the noise had originated and continued working for a few seconds, but then we felt the railway cart begin vibrating and looked out from under the boat between the keel blocks to see the pier pylons starting to go by like a picket fence.
We then realized the marine railway had broken loose and the boat and railway cart were going toward the river like a giant rollercoaster gaining speed, and we ran out from between the keel blocks. By then the boat was shifting a little and vibrating on the blocks, but the boat stayed on the blocks.
Somewhere about then we heard the GQ alarm go and the order over the 1MC topside speaker “General Quarters shut all hatches and watertight doors”.
All of us near enough ran to the end of the cart to jump off but in seeing those big chains sliding in the mud we stopped short and instead ran to the scaffolding and scurried up the scaffolding ladders. Part way up the scaffolding ladder I looked down toward the stern and the rapidly approaching river water in time to see the marine railway cart begin to hit the water. At that same glance I also saw one of the crew members who was near stern of the boat on the railway cart running like a track star with a wall of water right behind him. All the while the tremendous force of the water ripped up some of the marine railway cart planking like tooth picks (these planks were huge in cross section). As the marine railway cart was being forced under water a wall of water was forming a big wave not too far behind the guy running. One of the guys next to me on the scaffold MM1 (SS) Oli Stiles yelled to him “don't look back, run like hell”.
A few seconds later we were seeing the water begin to hit the scaffolding which in turn began twisting up and collapsing and scaffold planks and other stuff falling everywhere including the brow from the scaffold to topside. We had no other choice but to climb to the top of the scaffolding and get ready to jump into the water when we could do so, but the water wasn't quite up to us yet.
I looked back to see if the guy running up the cart was still running but all I could see was his white hard hat floating along in the wave of water which had formed as a result of the marine railway cart being rapidly submerged in the river water.
I looked over on the boat topside and saw one of the Phillipino stewards trying to open the after battery hatch to get below and all the while someone inside the boat was turning the after battery hatch wheel shut, and I could see the steward loosing the wrestling match with the hatch wheel and he was yelling something in his native language (don't think I want to know what he said).
About then the water began rushing past the scaffold just below us and we could feel the scaffold begin twisting, but the water outside of the scaffold looked safe enough so we all jumped in to get off the scaffolding that was progressively collapsing on its up the marine railway cart.
Once in the water and swimming, the rail crane operator rolled the crane down the pier and swung the big hook just over us so we could reach it and several of us wrapped our arms around the hook as he rotated the crane with us holding on the hook over to the pier ladder next to a pylon, then swung the hook out over the water to pick up more swimmers.
Once on I climbed up on the pier (cold and wet), I looked out into the river, and saw the boat had one diesel in operation and began getting underway but a plank flew up out of one of the screw guards.
I heard there were about 30 people under the boat in the railway, and no one had an injury more than a few stitches on one crew member who got cut from something during the ride.
Well, that's my memory of it anyway, and I guess I'm one of the few people on this planet who can say I almost had a submarine fall on me!!
As I recall one of boats screws and a shaft were damaged from the stern of the boat jamming into the river bottom before it had enough water under it for buoyancy.
Now the boat had damage on both ends, which is why we went into drydock.