Were all of our newest WW2 submarines identical?

As mentioned above, the three classes built during WW2 – Gato, Balao and Tench – were very similar but not quite identical. The Balao and Tench classes had thicker hulls and Tench boats had improved piping. This enabled the Balao and Tench boats to have an approved depth limit (test depth) of about 400 feet vs. 300 feet for the Gatos.

In addition, there could be some slight variation in equipment location. One tall skipper had the forward battery layout changed a bit so he could have a longer bunk and be able to stretch out. These variations were generally minor and were limited by functionality. Some changes depended on the preferences of the captains, most often on the commissioning (first) commanding officer.

One of the more apparent variations was the location of the large cannon. It could be located either forward or aft of the sail. It depended on whether the captain expected it to be used more often offensively (usually forward) or defensively (aft of the sail). The gun could get moved after commissioning if the current captain could talk the shipyard into making the change during a refit or overhaul.

If you knew one of these boats - or even an older fleet boat - and qualified on it, you wouldn’t need much time at all to qualify on another.

The differences among these three classes are not usually apparent to most observers.