Originally Posted by whiteminiman
What's wrong with a normal raft with an oar rig? or rather, what are you going to gain from a rigid bottom?
I'm not convinced that a rigid bottom would give you any more speed - although it may be more hydrodynamic, the weight will slow you down... and your ability to manoeuvre will be massively compromised!
Have you ever tried paddling a RIB - going in a straight line is easy, making the sort of moves that you'll want to make if you want to run anything more than Grade II is most definitely not.
No more spinning on the spot. No more carve turns into eddys. No more quick turns.
In my experience, SIBs wallow through the water like barges. The bottoms are rough, and the softness absorbs energy like under inflated tires. Cats are faster, but tend to be higher and less forgiving in the big stuff, there's a thread on the Yahoo GCPBA on them right now.
Dories weigh the same as rafts, once you add the frames, boxes etc to the raft, ~600
An 18 day raft usually weighs ~1500 with supplies and 2 people.
I've rowed a wooden dory in the GC (which has 2 class 10s)
and the rigid hull is a Ferrari compared even to a 16' raft, much less an 18' pig.
They do spin faster, and ferry better because of the side chines.
The river dories do not have the strakes and chines like most SW RIBs however, just a shallow vee and a hard edge to the gunwale.