The details used to be on the Diver Magazine website as aprt of the annual rib reviews but the page has disappeard and Ribnet only has the preamble article not the data.
Are you sure there is a 5m version, thought it was 4.9m and built in large numbers for the Royal Navy as well as divers. However the 4.9m is very shallow and has a low bow. The 5.1 and 5.3 did have an expedition model which were very tough little boats and there are still lots around from the early days so they obviously got it right.
From memory they were comparable with Delta, Opsrey, BWM et al, so the 5.3m would be about 250 - 300 kg for the hull (although what the manufacturers included in the hull did vary).
Ribnet is best viewed on a computer of some sort