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kjsailingSpring 02-23-2011 10:37 PM

Fiberglassing diesel tank into keel
Has anyone ever fiberglassed a polyurethane diesel tank into place? I'm considering fiberglassing over my diesel tank in the bilge/keel of my boat to seal it in on the top, keeping water out of the tank compartment. I'll put in two inspection ports so that I can reach the fittings on the tank.

Is this common?


sailingdog 02-24-2011 07:16 AM

Bad idea.... you can't inspect it to see if a leak develops if you've glassed over it all.

mitiempo 02-24-2011 10:19 AM

Tim Lackey foams tanks in place but does not glass over the top.
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micheck 02-24-2011 10:35 AM

I gather that you would be doing this AFTER you had filled the tank and let the plastic expand the 2-3% it does initially and then drained it.


mitiempo 02-24-2011 12:10 PM

No, Tim does it when it is empty. The foam will stop the tank from flexing and bulging which ultimately will weaken it. When builders foam in tanks they are new and empty as well.

kjsailingSpring 02-24-2011 01:06 PM

The top of the tank would be glassed but the sides have room to expand. I didn't want to foam it in because of the expansion issue, although it is very tempting cause it would be so easy. Could I fill it and then foam it? Fill it with water than foam it in?

Appreciate your input!

mitiempo 02-24-2011 02:26 PM

Why? Foaming it in empty will keep the tank from being distorted when it is full. Better for the tank, especially as removal will be difficult.:) I would leave the top open, one reason being to get at the gauge sender and clean out port if it has one. You don't want it to move but you will need access to the top someday.

kjsailingSpring 02-24-2011 03:12 PM

Thanks Brian...I'm going for the foam then, as is. Appreciate it!

mitiempo 02-24-2011 05:02 PM

Pour the foam a bit at a time so it doesn't get away from you as it expands. And mix it in small batches.

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