Mr.Schwab himself informed me that towards the end of the war he was turning out large destroyers in six weeks.

The Ford Company, as is well known, produced submarine chasers of the "Eagle" type in even a shorter period, but these vessels were of special design and construction.
I have dealt so far with the question of anti-submarine measures involving only the use of destroyers and other small surface craft.
There were, of course, other methods both in use and under consideration early in 1917 when we took stock of the situation.
For some time we had been using _Decoy vessels_, and with some success; it was possible to increase the number of these ships at the cost of taking merchant ships off the trade routes or by building.

A very considerable increase was arranged.
The use of our own _submarines_ offensively against enemy submarines had also been tried, and had met with occasional success, but our numbers were very limited (the total in December, 1916, fit for oversea or anti-submarine work was about forty).

They were much needed for reconnaissance and offensive work against surface men-of-war in enemy waters, and only a few were at the time available for anti-submarine operations, and then only at the cost of other important services.
The _hydrophone_ had been in the experimental stage and under trial for a considerable period, but it had not so far developed into an effective instrument for locating submarines, and although trials of the different patterns which had been devised were pushed forward with energy, many months elapsed before it became a practicable proposition.
One of the best offensive measures against the enemy submarines, it was realized, was the _mine_, if laid in sufficiently large numbers.
Unfortunately, in January, 1917, we did not possess a mine that was satisfactory against submarines.
Our deficiency in this respect was clearly shown in the course of some trials which I ordered, when one of our own submarines was run against a number of our mines, with the result that only about 33 per cent.

of the mines (fitted, of course, only with small charges) exploded.