Who writes this crap? If they had produced "thousands" rather than the hundreds they did produce we'd have had a much tougher time in the Atlantic and it was tough enough as it was. If they had even had the several hundred Donetz was promised he'd have before starting the war they'd have easily starved Englind into a negotiated settlement early on.
And even worse: Back then you need 3 torpedoes (4 torpedoes at warships), each fired at less than 1000 yards, by eyesight and periscope - fired by a manual fire control “analog computer” to a barely visible target - invisible on a dark night.
So 24 torpedoes - if all were fired “might” sink 6 or 8 targets (and rarely even that!)!
But consider that each target was 3,000 tons, perhaps 6-8,000 tons. A few “large” merchants were 10,000 tons. A very, very successful US submarine skipper sunk 100,000 tons in the ENTIRE war! Most were considered “successful” if they sunk 12,000 to 20,000 tons - over 4-6 missions.
Now: Today. A single torpedo fired from 24,000 yards out, fired using a passive sonar track capable of starting a track at 60,000 yards to 100,000 yards, can assure the engine room or propeller WILL BE destroyed by a single explosion. There are NO defenses, NO warning, and even if the merchant turns or hears the torpedo, it CANNOT escape and CANNOT outrun the torpedo.
One sonar signal, one attack, one torpedo, one target. One target gone. And most of today’s targets (merchants) are single engine, single propeller, single rudder, single crew averaging 60,000 to 120,000 tons. EACH. Oil and bulk cargo? 150,000 to 250,000 tons. Takes 2 years to build - assuming you can find an engine.
The UK would have deployed their Pykrete carriers to deal with the subs.