Are you looking to model a post war USN fleet boat? Take a look at this. Iron Bottom Sound announces the release of their 1/144 scale Electric Boat step sail.. With this resin sail you can convert your Trumpeter Gato in to a post-war Fleet Snorkel boat. The retail price for this conversion sail is $39.50.

History of the Fleet Snorkel Boat
The Fleet Snorkel boats were simply fleet boats with added snorkel induction and exhaust piping and masts. They also had their deck guns removed and sonar electronics installed where the gun magazine had been, but few or none of the other GUPPY modifications. These modifications were intended as an austere and less expensive alternative to GUPPY. Within two years of the end of the war, the U.S. Navy had a functional snorkel mast on an operational, high speed submarine- the Irex (SS 482).
During World War II German submarine losses increased sharply as radar-equipped Allied aircraft attacked U-boats running on the surface recharging their batteries. To charge the batteries that powered the electric motors for submerged operations, all submarines had to surface to run their air-breathing diesel engines. To counter the Allied radar threat the Germans perfected a Dutch device known as the snorkel. Using a snorkel a submarine could run its diesel engines and recharge its batteries while operating just below the surface. Air for the diesel engines was drawn into the submarine through the snorkel that was extended to the surface. To some extent the snorkel reduced vulnerability to detection and attack, but it protruded above the surface and could be detected by radar. The Germans introduced the snorkel too late in the war to make a difference.
The snorkel became a standard fixture of all diesel-electric submarines. Developed in its modern form by Germany in World War II, it was widely adopted and improved after the war. Basically, the snorkel connects a submerged submarine's diesels to the atmosphere through a pair of tubes, one for air intake, one for exhaust. A key feature is the head-valve on top of the air-intake mast that prevents water from entering. Before the snorkel, submarines had to surface to run their air-breathing diesel engines, but snorkel-equipped submarines can remain submerged, with only the tip of a mast exposed above the water for the required air.