Hull shapes / specs ?

[Trimix]

Reading the thread about Ribcraft vs Ribeye got me thinking about
manufactures specs for the shape of the hull.
Im looking for a 7m RIB and Ive been looking at loads of websites - which are of course basically marketing. So, before I try to get a test of each one Id like to narrow it down a bit based on certain criteria.
When people talk about a 'V' shaped hull thats good in rough conditions just what exactly do they mean ? All the hulls are V shaped
So, just what angle makes it good for the rough, and why are they not all like that. Whats the downside to a hull that can cope with the rough ? Can you have a hull that too 'V' shaped ?
Im looking for a boat that will be used in Corsica for Diving / Cruising / Exploring / Watersports.
Ive looked at loads of specs and cant see any real detail about the hull, other than the comment that they are a deep V shape.
Any one any idea ?