Building integrated fuel tank into a rib

Hi all,

My first post here.

Below are pics of bow compartment of my Caribe CL13 RIB. There used to be an aluminum fuel tank of about 10 gallons which has failed due to crevice corrosion because the compartment does get sea water in and the bare tank is simply sitting on the hull inside. Besides, it is also not utilizing the whole volume of the compartment.

As you can see, the inside is fairly smooth and enclosed on all sides except the top which is accessible. Here is my question:

If I would cover all the inside of the compartment with 1/2" thick neoprene foam sheet in a smooth way, couldn't I just built a vinyl ester tank from the outside in?

I would then build up from the bottom and up the sides to the top, then built an internal foam support frame at the top, resting on the cured sides, and then continue fiberglassing in the top, leaving an approx. 8x8 opening in the middle of the top where I could laminate an aluminum support frame for an inspection cover. Let it all cure and remove foam support through the inspection frame and install the inspection frame with gaskets to support frame. The inspection cover would then have the filler hose, gauge, vent and pick-up attachments.

The neoprene foam would keep the tank 1/2" floating from the hull and allow it to flex, I would maximize the volume, would have all the attachment points serviceable and I could get to the inside of the tank should the need arise.

What do you think and where could I have additional info on this?

Thank you,
David

 

Your idea is a good one, when the additional weight in the bow is no problem, you should check that!
Two changes in your setup I would recommend though.
Leave the hands off of polyester / vinylester, use Epoxy! It gives a tight bond which poly does´nt, is much easier to handle, and lasts.
The neoprene is not needed, the tank will become part of the structure. Just make sure that the fuel can expand (should be given through the tank vent).

When you leave the neoprene you´ll end up cheaper whith ep than with your setup!

Regards
Richard

 

Apex, thanks for your reply.

First, I thought it might be better to float the tank so that the hull can flex independently without putting any stress on the tank and that might eliminate stress cracks in the tank.

Secondly, we have here in California gas with 10% ethanol. From what I read, this ethanol attacks the epoxy but vinyl ester resin is more immune to that?

Thanks,
David

 

I have been doing gas tank repairs on epoxy boats for a while now and there is a very long list of materials including a special resin that is needed in doing the repair of epoxy tanks because Ethanol is a solvent and might i mention that i have a thread on this forum titled Skater 32 & in fact it is in the same section as your Thread and i will be showing pic's of everything that has been done to the boat at this time including all the steps or process that need's to be done to repair the tanks on a Skater which is an Epoxy boat from the lid's , baffles , and everything else that is involved in doing the tanks ......................

 

Great, I am looking forward to see how you are doing it.

 

I forgot to mention that i have seen where the Ethanol has eaten thru the inside of the epoxy tanks so bad that it has seeped into the core & causing a much bigger problem and all the tanks that i have worked on are sturcturally built into the boat so.................... with that in mind go with your gut feeling because epoxy tanks can not stand Ethanol and like i said before i use a long list of materials to do this type of repair & the witches brew ( resin ) is not $$ cheap .

 

Sorry guys,

did´nt think about petrol and ethanol! I´m just not used with having other than diesel propulsion. (and will never have)

Regards
Richard