How to handle conflicting submarine statistics

Published dimensions and displacements for these submarines often conflict across online articles and books. Direct archive work was unavailable, including access to Cammell Laird records for many British boats. Norman Friedman's Submarines in Two World Wars therefore supplies one consistent set of technical figures, although reservations about some of Friedman's work remain explicit. This source choice makes the class comparisons internally consistent while keeping the limits of the figures visible.