How 22-knot Liberty ships change the convoy war

What if Liberty ships were larger and capable of at least 22 knots without greatly reducing numbers?

The U-boat campaign would become far harder, but only if American industry massively expanded turbine production.

At roughly 22 knots, a convoy could pass a submarine's attack position after only one or two shots. Higher sustained speed also compresses the time available for a U-boat to reposition for another attack. This would transform the tactical problem for submarines. It would also shift the American production bottleneck from merchant hull assembly to machinery, because triple-expansion engines could not deliver the required speed and turbine output would have to expand enormously.