In several of my books there are references to RN plans in the 1980s to build more than the 4 Upholder class SSKs that ultimately entered service.
(The sources suggest a 'planned' total of 10-12 boats at one stage).
The same books talk about Boat No.5 onwards being built to a 'stretched' design displacing c.3,000 tons surfaced (rather than 2,185 tons for the boats actually built). Much of this increase was to provide for a greater range.
Does anyone know what the proposed range for these 'stretched' boats was supposed to be? (the boats actually built could do c. 8,000 n.miles at 8 knots snorkelled)
Also, were they planning to increase the weapons load from 18 weapons in this longer boat?
Many thanks in advance.