Integral Fuel Tank Material advice please

[neelie]

Hello

I am looking to buy at a Cat with integral fuel tanks (diesel). They are located in the forward bridge deck region and contain a total of some 200 gallons. Also, they are really inaccessible and difficult to inspect.

The vessel is constructed of divinycell with Vinylester resins, was professionally built and so I am assuming that the tanks were constructed properly with baffles etc.

I am concerned that it is very difficult to actually guarantee that a FRP tank is "diesel proof" and that if/when the diesel leaks into the core material, I will end up owning a boat that is not economically feasible to repair.

If I buy it, should I consider major surgery and installing aluminum tanks before a leak and subsequent core failure occurs?

Any thoughts / advice appreciated

Thanks
niels

[rwatson]

You can get attachments to video cameras that insert into enclosed spaces so you can see what is going on.
With diesel, it may not just be the tanks construction that needs attention, but unless they have some kind of fuel scrubbing equipment on board, they probably have a lot of horrible gunge in them as well.
First rule of thumb in buying a secondhand boat - what you cant see ... assume the worst!

[dragonjbynight]

I am not sure if it's exactly what your looking for, but if you think they are leaking/have leaked, you can take a small sample of the core material near the tanks and have it tested for the presence of diesel....I think i heard that somewhere anyways.....

[the1much]

i think your on the right track,,,,even if their not leaking,,,switching to alum. is safer, they last longer,,,and for an example,,i took out 2 old glass tanks from a truck,,,and we could put our hand right through them.,,im actually surprised that theres a builder that pays all that extra money for their liability insurence , for putting them in.,,,to make short,,,if changing them aint a big thing to ya,,,,,,i would buy the boat and change them,,,,,if there isnt alot of other money going into other things thats wrong with the boat.

[neelie]

Thanks for the replies.

No I don't think it has leaked - the boat is well built. I am more concerned about the suitability of the materials used for construction (I.e divinycell & vinylester) of the tank. There obviously must be reason why a lot of new FRP boats still come with aluminum fuel tanks instead of having them built in?
Taking a core ample is out of the question - I am limited to NDT as its not yet my boat.

As far as grungy fuel - this will be no different to any other tank except for the lack of access panels. Also, with baffles built in, there is not much one can actually see.

In short, are there any major objections to a fuel tank constructed out of cored Divinycell using Vinylester resins?

the1much: The diesel chewed through fibreglass? I was always told that it wouldn't unless there were additives like ethanol etc. Now, you've got me worried!. All I need to do now is price the work required to cut a huge hole in the bridge deck to allow the insertion of aluminum tanks - it may well be a deal killer.

[the1much]

yes there is a good reason most boats still have alum. tanks,,,,cause fiberglass tanks will always rot,,,are brittle,,and prone to leaking,,,,,ie:most companies either cant afford the liability insurance,,or cant find one that will carry them for it.and the truck used regular gas,,and was made with vinyle,,,but ALL fuels are corrosive,,and it didnt eat all the way through,,,but the minute we touched it our fingers went through.,,,now that im in texas, i do alot of oil field work,,,there are a FEW,,(can count on toes and fingers) tanks made from glass,,and they use some freaked out kind of resin,,,,but they seem to be getting rid of them and going alum.,,,even for those big 5000 barrel tanks,,hehe ,,,,ooooo,,,all this comming from a glass dude,,hehe

[raw]

The tank you speak of may have been designed to be a solid skin frp tank that has been laminated onto a foam cored panel. ie, the internal laminate is identical to that required for a solid skin tank. We sometimes spec like this to get around the no cored tank requirements some standards specify.

As far as glass tanks go, there are plenty of builders doing them. In fact, the largest builder near to you makes hundreds per year. I have no problems with them personally.

Alum tanks are often specified since they can be outsourced easily and tested off the boat. Each builder has his own preferences and solutions.

What boat is this? Sounds familar.