Rigid Inflatable Modification Questions/Advice

[drhobbs]

Have an Avon 5.4m RIB and looking to do a couple modifications to gain some deck space, keeps things a tad drier, and maybe gain a bit of performance. Right now the hull is sealed and has a small section of foam flotation glassed to the underside of the deck about amidships(as viewed through an inspection port in the transom). The hull and decks are in great shape (although tubes could use some work). What I would like to do is add a below deck fuel tank and a bilge in the traditional sense (right now my bilge is a pump sitting against the transom, above decks, in the stern). There is no storage other than a few dry bags lashed to the deck in the bow, and the 15 gallon fuel tank in the stern takes up most of the foot space behind the leaning post. This leaves the console, which is relatively small. I dont think I'll be able to stow a ton of gear, but what I would like to do is add a bow locker (fairly straight-forward). An engine bracket may be in order as well.

My concerns are that 1) the deck is 'sealed' in that it has no hatches or drains - i dont want to create an issue with structural integrity (or generally muck up a nice tidy boat) or 2) how do i install the tank both what method should i use to cut up the deck and so it stays put, and 3) how do I build a bildge, below-decks rather than above?

Id appreciate any help or advice anyone can send along.

Thanks - DH

[Willallison]

If I understand you correctly, you want to chop some holes in the deck surface. The largest would be to install an underfloor fuel tank, others would be to allow water to drain into the underfloor space. Correct?
My 1st thought is that there is generally not a lot of space under there - can you get a tank in large enough to give you the required amount of tankage?
2n is that the fuel tank will then be in the same space as all that bilge water. Not all that unusual I guess, but something that should be taken into consideration when looking at tank construction - poly would be my 1st choice.
I guess you could cut a hatch into the floor and install a fuel bladder, which would drastically reduce the size hole you have to make. You should be able to do that without compromising the structural integrity too much. We have an Avon RIB (though a smaller one) and they are quite heavily built in the 1st place.

[drhobbs]

I had the same thoughts on the amount of space... from a rough estimate based on visual inspection (ie far from precise) one of the longer, shorter, poly tanks could be made to work. That would require some cutting - enough to get the tank in, and then some other hatches or equivalent to fasten the tank in place. Of course, making the bilge could just be a matter of cutting a couple drain holes in the deck, and then dropping the pump below deck. having a hatch or two would also help with running the cables etc below the deck as well... i think.