USS Grayback was found after an amateur historian made a startling discovery.

USS Grayback, a U.S. Navy submarine lost in 1944 to enemy air attack, has been found. The search was conducted by U.S. and Japanese researchers who were the first to realize that an error in translation had misplaced the location of the ship’s sinking. A search party utilizing drones fitted with high-definition cameras located the shattered submarine, making a positive identification.

USS Grayback (SS-208) was a Tambor-class submarine. Grayback was 307 feet long and 27 feet wide, with a top speed of 20.9 knots surfaced and 8.75 knots submerged. She had a crew of 65 and was armed with ten torpedo tubes—six facing forward and four backward—a 76-millimeter gun, 40-millimeter gun, and .50-caliber machine gun. Grayback displaced just 1,470 tons, making her less than one-fifth the size of today’s Virginia-class submarines.

The submarine conducted a string of highly successful patrols in the western Pacific, ten in all. Grayback sank 14 Japanese ships, or 63,835 tons of enemy shipping, a figure that translates into nearly 40 times the submarine's own weight. She even sank the Imperial Japanese Navy submarine I-18, despite submarine vs. submarine warfare is a relatively uncommon occurrence in World War II. Her luck ran out on February 26, 1944, when she was sunk off the coast of Okinawa. The Navy realized she had been lost in March after she was reported overdue returning to Midway Island.

U.S. Navy officials only found out the cause of Grayback’s sinking after the war, when translated Japanese wartime records noted a Nakajima B5N “Kate” bomber attacked a surfaced enemy submarine with a 500-pound bomb. The stricken submarine was then bombarded with depth charges. Unfortunately, according to The New York Times, a single-digit error in the grid coordinates of the Navy’s translation resulted in the Navy believing she was actually a hundred miles away from her true location.

An amateur Japanese historian and researcher, Yutaka Iwasaki, was examining the Japanese Navy’s wartime records and realized the coordinates of the sinking were incorrect. Iwasaki’s research was brought to the attention of underwater Tim Taylor, whose Lost 52 Project plans to locate the remains of every one of the 52 U.S. Navy submarines lost during World War II.

Although the U.S. Pacific Fleet submarine force was spectacularly effective in depriving Japan from food, oil, and other resources, the loss of 52 submarines and 3,505 submariners was the highest among all the services, amounting to 22 percent of all submarine force personnel.

Taylor’s team of explorers sailed to the correct coordinates and deployed an autonomous underwater vehicle (AUV) fitted with sonar. The AUV scanned the seabed below, beaming data to the surface for analysis. Taylor noticed two anomalies just as the AUV began to malfunction, and sent another unmanned submersible armed with cameras to investigate. Grayback had been found.

Grayback was found in two pieces on the bottom of the ocean, with the front end broken off from the rest of the submarine and a large hole in the stern. These locations roughly correspond to the front and rear torpedo rooms. A Tambor-class submarine held 24 Mark 14 torpedoes, each packing 507 pounds of TNT. The forward section appears to have sustained a larger explosion, large enough to break the ship into two pieces, and indeed the forward torpedo room held more torpedoes than the rear torpedo room.

The sonar image of Grayback also shows serious damage behind the submarine’s sail. This was the location of the 76-millimeter (3-inch) deck gun, which was blown off by the Japanese aerial bomb. Explorers located the deck gun 400 feet from the submarine.

Grayback’s loss, to an aircraft while on the surface of the water, is one good reason the U.S. Navy today maintains an all-nuclear powered submarine fleet. The diesel engines of conventionally powered submarines cannot operate while the sub is underwater. This forced submarines like Grayback to operate on the surface whenever possible, submerging at the first sign of the enemy. For Grayback, that was a fatal drawback. Modern nuclear submarines can travel submerged indefinitely, and U.S. Navy submarines can conduct an entire patrol underwater, unseen.

(Source: Kyle Mizokami, Popular Mechanics- 12/11/2019)

https://www.popularmechanics.com/military/navy-ships/a29765905/uss-grayback-discovery/