Were German World War I submarines technically superior?

Did Germany hold a clear diesel and submarine-technology advantage over Britain in World War I?

Not in straightforward operational terms; German boats pursued higher engine power, while British designs emphasized reliability and may also have benefited from better welding.

British and German submarines are treated as broadly comparable, with British welding perhaps offering an advantage. German diesels pursued higher theoretical horsepower, but that output depended partly on highly refined fuel. With ordinary service fuel, the engines could lose performance and become less reliable. British engines increased power more slowly while emphasizing dependable operation. The comparison cannot be reduced to specifications because construction quality, fuel supply, and repeatable performance all shaped fighting value.