Could submarine size limits favour coastal defence?

Would a later naval treaty try to restrict submarine size rather than prohibit submarines?

That approach is considered worth trying, with coastal and harbour boats accepted and the ceiling chosen carefully.

A size limit is proposed as an alternative to trying to eliminate submarines by treaty. Presenting small coastal and harbour submarines as acceptable would permit a defensive role while constraining larger boats. The exchange considers the idea feasible but does not settle a clear final ceiling. A confused numerical exchange is corrected as a range for individual boat size, rather than a cumulative allocation. Britain's T class is then mentioned as a reason to consider the effect on one's own future designs.