What were the Navy’s problems at the beginning of the war?

In no particular order, some of the issues for submarines were a shortage of combat-ready ships; submarine captains who had been trained to be too conservative; significant torpedo problems; a faulty assumption that submarines would sail with the fleet; and the need to learn how to fight a modern war. In more detail:

The shortage of combat-ready ships of all types. President Franklin Roosevelt had been walking a tightrope between trying to keep the country out of the war, as most of the public preferred, and preparing to fight in the likely global conflict. Fortunately, he managed to get funding from Congress to start building the ships we would need. Unfortunately, it would take time to complete the ships that were ordered and then to build enough facilities to increase production after the attack on Pearl Harbor. The first submarine of the new Gato designs to be completed, the USS Drum (SS-228), had just been commissioned on November 1, 1941, in Kittery, Maine and was still on shakedown, post construction repairs and crew training. She wouldn’t have been ready for combat until the spring of 1942.

Submarine captains had been trained to be conservative. Pre-war training taught that if your boat was sighted, you were assumed to have been sunk. Being sighted in combat wasn’t usually a good thing, but it wasn’t always fatal either. As a result of the conservative approach, captains were taught to fire torpedoes based on sonar bearings rather than risking having the periscope being seen. We quickly established that sonar bearings alone weren’t good enough. Visual bearings to the targets were needed, particularly until we improved the quality of our sonar.

In order to overcome these mistakes in training and procedures, we would wind up replacing about one-third of the officers who were in command of submarines at the beginning of the war.

Not every good commanding officer in peace time would be aggressive enough for command in the war. A general rule was that if a captain didn’t produce results within two war patrols, he would likely have been reassigned. Some captains who “washed out” of submarines went on to distinguished careers in surface ships.

We had significant torpedo problems. These are detailed in the section on torpedoes. Generally speaking, testing was woefully inadequate and the Torpedo Bureau refused to believe that the problems were in the torpedoes. The main issues were that the torpedoes ran too deep; the magnetic exploders generally did not work properly; and the contact exploders didn’t always work either. It would take almost two years to identify, acknowledge and then fix the major problems with our torpedoes. It appears that, even then, no one was held accountable.

The assumption that submarines would sail with the fleet and engage the enemy before the big gun battles. That’s why they were called “fleet boats”. In hindsight, there were obvious problems with this theory:

1. After the attack on Pearl Harbor, there wasn’t much of a fleet for submarines to sail with.
2. Even our newest submarines could barely keep up with our oldest and slowest battleships and cruisers. Even then, they would have to sail on the surface and give up their greatest advantage - stealth.
3. It ignored the lessons of the Atlantic War where the German U-boats were beginning to cut the supply routes to England, an island nation. Japan was just as dependent as Britain for the imported supplies needed to fight a war.

We needed to learn to fight a modern war. The United States was barely involved in the naval parts of WW1. There was a great deal of new equipment and technology that we needed to learn to use most effectively. Japan had already been at war in China for over five years. They had a great deal of combat experience and had been actively training for the war that we still wanted to avoid. It would take us about 18 months for us to catch up and become a truly effective fighting force.