RIB Design help

Ok. heres the deal. My latest boat is currently sitting on trailer in the UK. Thursday it will be put on a ship bound for the US.
18foot RIB.
when i built this boat, it was orginally built as a prototype. I worked with Concorde boats in Wales, and took a mold, originally for a sports fishing boat, and adpated it to work as a RIB, using Maxsurf and the trusty Jigsaw and Bondo. The console and seats etc on this boat were really just thrown together, as neat as possible and as best as possible, using plywood and glass fiber, just so the boat would function and look fairly good, but really just wanted to test the hull, see how it worked, and if it had any potential.
it did work, much better than anticipated. I believe Concorde even went on to produce the same RIB, which i cant really say anything about, it was their hull design in the first place. Anyway, its a shallow V hull, so is intended more for inshore coastal waters, but, although a little uncomfy, does perform very well out at sea in the rougher waters. So now i know this hull form works, I intend to get it over here, and redesign the hull again, ironing out the few little bugs it had, and redesigning it to more of a RIB, which i have no doubt will end up in a complete re design from the original, but using the same hull characteristics, maybe just a deeper V.

But anyway, my question is about the console and seats etc. I hope to reproduce this boat, and make molds of the consoles and seats etc, and produce it on a small scale really, custom fitted out to peoples wants, made to order type thing i guess, but i need some help from US users. Since i am from the UK, i dont really know yet how the US does things. From what i can gather, RIBs have not taken off here, only ones around are the expensive "luxury" RIBs, which arnt really RIBs, just luxury craft with an inflatable tube it seems. But i dont know what it is people want from their boat over here. Being in Tennessee, there is zero market for RIBs, as they are more expensive than your normal solid craft, and overkill for use on lakes etc. But i believe they are becomming known in places such as Florida, North Carolina etc, which i suppose is where i will aim for.
But what do people want from boats here? If you were to buy a RIB, what would you want from it. Obviously they have a lot of advantages over other boats in terms of stability, etc, but i just want to get an idea of how the american boat market works.

Also, need some help on the fuel tank. At the moment, it has a 43litre tank located under the drivers seat. Its a proper built in tank, made from plastic, using baffles and explosion resistant systems. basically i didnt build it myself, it was built by a fuel tank company especially for these boats. However, i dont like it under the seat. its under there because originally it was intended to have a simple 5 gallon portable tank, but i wanted a longer range, so added this tank as a last minute thought, as i had already built the deck etc into the boat.

I would like to fit a proper built in fuel tank, located under the deck, but have never done it before. Although on paper i can do it, since i am working with a pretty dangerous part of a boat, i would like some expert experience in fuel tanks to help me. How would it need supporting? can it just be fitted to the existing stringers, or will it need its own supports. Stainless steel or plastic. Stainless i know will be more expensive, and heavier, but are the benefits worth it?
Also, does anyone know the regulations in the states regarding fuel tanks?
Also having a job to figure out how to vent the tank. Since there are no sidewalls on this boat, i cant vent it out the side above the waterline. Would rather not vent it through the deck, 1 because of it being a hazard having a vent sticking up out the deck, and 2, keeping water form going down into it. Any suggestions on that? maybe vent it out the back of the drivers seat, like the current tank is, or is there a system that allows the tank to be vented inside the engine? i know on an old yamaha outboard i har, the vent was through the carb, somehow, but i dont know if this is a safe system, or even legal in the states.

Any help would be great. I dont expect to get rich off it, but would like to at least attempt it, Obviously i cant do much until i can actually have my own business (still waiting on paperwork etc from immigration that allows me to) but hope to start my own business eventually, if i can get this RIB up to professional grade, IE turn it from a prototype to a fully functioning final design and then hopefully expand from this.

 

A frame design

In my opinion, stainless steel this the way forward. Apart from the initial cost, its benefits far outweigh that of any plastic or composite tank.

Over the years I have rebuilt and fitted out several different types of boats.
I recently fitted two 49 gallon aluminium tanks into my lastest development. It should be noted that I have these aluminium tanks as they came about at the right time. I was planning to make my own however when they are on top of a skip within a local boat company yard, free is better than the cost of stainless sheeting.

Anyway the point i wish to make is that ribs are designed for abuse. They are designed to take high impact loads etc. I would made the tanks as low as possible inside the hull improve C of G etc. I would strap them in permantly with glass or something similar. To spread the loads further from a half empty tank, I would sandwich the tank to the hull with exspanded foam (make sure its non-water absorping thou).


Venting could be achieved with a pipe running up the inside on the A frame. If it hasn't got one, there good for all the navagation equipment etc. Having a pip as high as possible reduced fuel spillage in extreme conditions.

Buckle

 

thanks. stainless it is then. my only worry about stainless was its weight, but as you said, its benefits do make up for it.

My boat doesnt have an A frame, wanted something different to the normal stainless frame, so incorporates fins on the back, kind of like a large spoiler with the middle wing taken out. all nav lights, etc are mounted to that, and stainless steel tubing can be mounted across the top to house a self righting bag, if the need arises.
but im thinking i could vent the tank out in the engine well, which is high enough not to get swamped and is self draining if it does, so should be a good place, also help if fuel does manage to spill.

Thanks for your help