double-ender oar RIB for whitewater?

[rays]

Is there such a thing?
I've searched a bit and not seen one. The ideal boat would be a marriage of
http://www.boulderboatworks.com/bbw_boat_gc10_dory.html
and a Sotar
http://rjs.org/gc1/roll_2/IMG18.JPG

Since our last GC trip I have often pictured a 16' RIB, but as a double-ender. An ocean fishing RIB allows water to flood the vee when stopped (it usually flows out rear ports on accel). We would want to flood/pump that space at will...
I wanted to make a chined bottom/flat floor that would stitch into the Sotar tubes in place of the inflatable one, PE plastic, with holes drilled around the perimeter for rope stitch . Buoyancy and stability of a raft and speed of a dory. It would need to flex a good bit of course.
SO, do they exist?
Does anyone do custom solutions?

-Ray

[jyasaki]

Originally Posted by rays

An ocean fishing RIB allows water to flood the vee when stopped (it usually flows out rear ports on accel). We would want to flood/pump that space at will...

I wanted to make a chined bottom/flat floor

Umm... Isn't that statement an oxymoron?

Haven't heard of anything like what you're describing (which doesn't mean it isn't made); Might try contacting some of the one-off roto-molders or raft companies?

jky

[rays]

Originally Posted by jyasaki

Umm... Isn't that statement an oxymoron?

Haven't heard of anything like what you're describing (which doesn't mean it isn't made); Might try contacting some of the one-off roto-molders or raft companies?

jky

I'd meant to convey that there is the usual hollow bottom, floor surface is flat, but bottom is chined...
I'd guess a ~6" depth.

I tried emailing both Boulder and Sotar, we'll see.
I read the discussion on rescue rafts; one problem I'd see is if the RIB raft got turned around exposing a transom to wave action. I'm used to going through 10' waves in either direction...

[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.

The only advantage I can see is the additional weight is going to allow you to punch through bigger hydraulics... but I'm not convinced that's necessarily a healthy thing to be doing anyway (but then I'm a bit of a wimp!)

Cheers,
WMM

[rays]

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
http://www.boulderboatworks.com/bbw_boat_gc10_dory.html
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)
http://rjs.org/gc1/roll_2/IMG16.JPG
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.

Best,
Ray