Integral tanks?

[stubones99]

Some boats offer integral tanks molded into the fiberglass as the boat is being built. Most say they use specific types of resin based on the liquid being put in the tanks. My question is this; how long would they last and if you had a leak or problem with the integral tanks could it be resolved with a bladder being installed or non-permeable coating or is it a bigger problem?

 

[GregBrannon]

My boat was launched in 1977 with integral, fuel, water, and holding tanks. To my knowledge they've lasted this long without a problem. If a problem developed, repair would seem simple enough once access to the damaged or failing area was achieved, which might not be so simple. I've made many lousy assumptions about the complexity of boat repairs, and I hope I never have to test this one.


Why do you ask?

 

[Comodave]

On a previous boat, we had integral water and holding tanks. The boat was about 20 years old at the time. We kept getting small white particles in the water. Finally figured out it was the gel coat on the inside of the tank breaking down. Removed the tanks with a sawsall and installed new plastic custom made water tanks. The holding tank never gave us any problems, thank goodness. It had a “black iron” fuel tank that had rust scaling on the bottom exterior. Also took it out with a sawsall and had a custom fiberglass tank made that was bonded into the boat.

 

[Larry M]

Our water tanks are integral fiberglass tanks. I wish our fuel tanks had been also. Some earlier Krogen 42’s have integral fiberglass fuel tanks and I haven’t heard of any failures. I also beleave Hatteras had intergral fuel tanks in a lot of their models with good success.

Properly done, I think they’d be preferred over steel or aluminum. Shouldn’t they last as long as a fiberglass boat?

 

[AusCan]

I've got integral water tanks on the outer sides about midship. They are still like new after 36 years as far as I can tell. I drink the unfiltered water straight from the tanks and have not noticed any residue.

The bonus is - if the hull is ever compromised in that area, the issue can be easily controlled by simply isolating that tank.

 

[caltexflanc]

I too owned an old Hatteras (1981 56MY) which had integral fuel and holding tanks down the middle, the water tanks consisted of a semi-molded in unit and one along the transom, again all centered and molded fiberglass. Great design in my opinion, helped keep CG low and made use of space otherwise wasted on a lot of boats, a freed up a lot of space otherwise occupied on many boats. I've been pretty active with other Hatteras owners, and have never heard of anyone having an issue.There are a lot of 35+ year old Hatts out there still doing fine. I'll qualify that as it seems to me someone must have had issues with the gasoline powered boats which Hatt made a few of, and Ethanol; I just haven't run across one.

I've been told by old Hatteras hands (a lot of them around here, and a few of them did work on my boat when I owned it) that it is a more expensive design to do correctly.

 

[Insequent]

When I was having my refit done in Port Townsend 5 years ago there was a smallish Selene in the yard (40'+). It had molded GRP diesel tanks. There was diesel coming out of one of the stingers in the ER, believed to have resulted from a fuel tank failure. Not sure how it all turned out. Might have been a quite difficult repair.

Molded GRP tanks would still be my choice in a new build. Sure, they need to be both well engineered and well constructed. Overall, I think it the simplest solution. Modern epoxy paints on mild steel is very good. But the tanks still need to be mounted and held in place, and can get resonant vibrations from engine leading to cracking at welds, including where internal baffles are located (more an issue for aluminium though)