The Infamous Mink Blanket Dive
By
David L. Johnston
© 2007

"Trimming" is a term used by submariners to describe the process of adjusting the boat's weight so as to obtain neutral buoyancy, neither sinking or rising. This is achieved by letting in or pumping water out of ballast tanks located forward and aft and in the center of the boat. It's a tricky process and requires taking into account obscure factors such as fuel and water usage, how many torpedoes have been shot, how much garbage has been dumped, ...and how much shopping the crew has done in Korea.

It's June, 1984 and my old diesel boat, the USS Darter (SS-576) is cruising along on the surface of the Korea Strait. We had just finished a port visit in Chinhae, Korea and were enroute to a "show the flag" visit to the big Japanese naval base in Kure.

Korea was known for its good shopping and the crew had gone all out this trip, turning the boat into a tramp steamer, loading her down with numerous souvenirs, big and small. On one trip, a shipmate even brought down a disassembled brass bed! The favorite among these souvenirs was a large, heavy, imitation fur blanket that felt a lot like mink if you imagined hard enough. Even when folded, they were far too big to fit in the bunk or wall lockers, so the Forward Torpedo Room crew grudgingly allowed them to be stowed in plastic bags in the "pit" under the deck plates between the reload torpedoes. An exact count for this trip was never obtained, but it was estimated to be about 25-30.

The captain thought we were riding a little low in the water and wanted to be in good surface trim so we would look smart and squared away for the Japanese. So he ordered a quick dive to periscope depth (48 feet) just long enough to trim up the boat and we could be on our way. "No problem", we thought, "we can handle that."

After pulling the plug, the Darter would normally settle until she reached about 30 feet, then she would hang for a short time while the superstructure atop the pressure hull filled with water. Then the bow planesman would ease her down to 48 feet. This time, however, as soon as the ballast tank vents opened to start the dive, the old girl dropped like a rock and took a large down angle. We were way out of trim forward, and very heavy overall, but we couldn't pump the water aft and overboard fast enough. At the control stations, the planesmen had the yokes for the diving planes pulled into their chests in an attempt to lessen the angle and the propellers were spinning in full reverse, but down she went with a bone in her teeth.

I was a young non-qual on my first run, mess-cooking in the scullery when the diving alarm sounded. At first I thought that the guys in control were having a little fun with the angles as they were known to do at times, but I soon realized that we were in some deep doo-doo. As the deck tilted, I planted my rear against the sink and one knee and both hands against the dishes on the opposite side to keep them from falling. All color must have drained from my face as a very senior petty officer announced to everyone on the mess decks that we could "kiss our butts goodbye."

After a brief but valiant effort, the boys in Control realized that they were not going to pull her out, so the captain ordered an Emergency Blow, a procedure that rapidly empties the ballast tanks with high pressure air and sends us up like a rocket. In a very short period of time I went from lying on my back on the sink to my hands and knees on the dish locker. Unfortunately, the helmsman didn't quite have the rudder amidships when we started up and just prior to breaking the surface, we snap rolled hard to the left, then back to the right when the superstructure cleared the water. Everything on the Mess Decks that wasn't secured went flying. We had just finished chow and cups, food, toasters, even a sailor or two found themselves in flight. An Engineman by the name of Bill Hutton took one of the aforementioned toasters alongside his head and got a nasty cut. No one else got hurt, thank God, but it sure as hell scared the bejesus out of us. Some people pay good money for a roller coaster ride like that!

Being the dumb non-qual that I was at the time, when word came back that we had been really heavy forward because of all the mink blankets in the pit in the Torpedo Room, I believed it and decided I was never going to bring another of the damned things aboard unless I checked with my chief first.

In all seriousness, the real reason for this near disaster was a simple one…the transposing of digits when figuring ballast compensation and the failure to properly record fuel usage from a forward fuel tank. This sobering realization served its purpose and everyone took it to heart. It was a reminder of the very dangerous nature of submarining.

Over the history of the submarine force, dozens of these minor incidents took place, but only a few ended in tragedy. Each time the sailors on the boats learned from the mistakes and made our boats and the men who sailed them the best in the world.