204

USS Mackerel (SS-204)

Mackerel on her builder's trials in Long Island Sound, March 22, 1941. Mackerel had been built with the aft end of her fairwater already cut down, providing an excellent location for an additional M2 .50 caliber water cooled machine gun. She would later have a 3"/50 caliber Mk 6 gun added aft of the fairwater.

Photo from the U.S. National Archives via Historylink101.com.

A port quarter view of Mackerel at rest during trials, March 22, 1941. The aft superstructure of this boat ran all the way to the tip of the stern, much like the Porpoise and Salmon/Sargo-class boats. Just aft of the periscope shears is a circular Radio Direction Finding (RDF) loop antenna.

Photo from the U.S. National Archives via Historylink101.com.

Mackerel underway at full speed during builder's trials in Long Island Sound, March 22, 1941. A full speed run on a measured mile was a required part of the trials. It proved that the submarine could make the speed that was specified in the contract, in this case a maximum of 16 knots. Mackerel had a direct drive propulsion train, where the main engines were clutched to the propeller shaft, which also ran through the main motors, which doubled as generators for battery charging. Clutches allowed the crew to either use the main engines for propulsion or for battery charging, or to declutch the main engine when running on the battery and motors while submerged. Unlike her fleet submarine sisters, Mackerel and Marlin had only two main engines.

USN photo # 19-N-23871 from the Bureau of Ships Collection in the U.S. National Archives.

Close up of the photo above, showing details of Mackerel's original conning tower fairwater configuration. On the top of the covered pilothouse is a mount for a M2 .50 caliber machine gun, similar to the mount on the aft fairwater deck. Her two periscopes and radio mast are protected by fully plated shears. This would later be unplated. A circular LF radio loop antenna is mounted on the aft fairwater deck. This could receive LF radio transmissions while the boat was at periscope depth. The conning tower itself (inside the fairwater) was actually very small (unlike the fleet boats), not much more than an access trunk for the bridge. All of the torpedo fire control equipment was located in the control room.

USN photo # 19-N-23871 from the Bureau of Ships Collection in the U.S. National Archives.

Screenshot from the movie Crash Dive by 20th Century Fox, 1943. The outdoor scenes were filmed during the summer of 1942 entirely at the Naval Submarine Base New London, CT. with full Navy cooperation. Compared with the photo above, by this time the .50 caliber mount had been removed from the top of Mackerel's pilothouse, and plating had been removed from around the periscope shears, but radar had not yet been installed. Installation priority for radar went to the boats on war patrol in the Pacific.

Screenshot from the movie Crash Dive, by the webmasters.

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