Integral Tank Construction

[Bermuda30]

Hello all,

Interested in the construction of hull integrated water tanks. Exactly how are they built? I like the basic idea of having weight of the water as low as possible within the hull. I also like the idea that a tank built forward under the v-berth would be functional as a sort of collision locker/bulkhead. So, can any one point me in the right direction for this construction process? Thanks for your time.

[sailingdog]

Building tanks is pretty simple. For potable water use, you will need to coat the interior of the tank with CeRAM-Cote 54 or something similar. Standard epoxies are not really fit for potable water use. BTW, the manufacturer of my boat uses the CeRAM-Cote 54 for the built-in tanks.

[AjariBonten]

I don't think I would want to put that much weight so far forward in the boat. Wouldn't that lend towards hobbyhorsing?

[Bermuda30]

SD- How exactly does one go about the construction though? Particularly getting the cavity? Appreciate the thoughts on use with potable water, thought that may be an issue but was saving it for later.

Ajari- Was also considering this. Right now just looking at the construction processes and gathering ideas, may not be building it fully forward. Water certainly is heavy. Maybe one tank forward and one aft? Might take a little thought when consuming as to balance the load, but maybe?

BTW, the current plastic tank (cracked) is placed forward against the hull under the v-berth. Sorry, don't know the capacity. Thanks again all.

[sailingdog]

Measure the space and make a mold out of plywood. Fillet the corners and edges with thickened epoxy. Let cure. Spray with PVA or mold release. Then make the tank using the mold...gelcoat, then fiberglass, then core material if you're going to use it...and then more fiberglass. Make sure you make a flange at the top, so you can fasten the top of the tank down.

[deniseO30]

buy a plastic welder and plastic sheets? Theres a plastic tank shop not far from where I live. they weld all kinds of poly. don't forget baffles to stop the sloshing. Do a web search for " plastic welder" see what comes up!

[Bermuda30]

SD- Thanks yet again, very helpful!

Denise- Was considering making a contoured SS tank this way. (I'm pretty good with metals, not sure about plastics). About the baffles; exactly how are these built? Half bulkheads, bulkheads with holes,...?

Again, thanks for the help!

[Sailormann]

Stainless steel is not great. Corrodes. Plastic is very good. it would be a good idea to create the places where you want to put the tanks and then have plastic tanks made to fit in. You could do it so that the whole top of the tank came off for easy cleaning.

It's hard to avoid chemical taste when you have your drinking water sitting in fibreglass or epoxy resin. It can also seep into the hull if you haven't sealed it perfectly, which is harder to do than it sounds.

[Rockter]

The chemical taste risk would put me off.
Stainless, WHEN OXYGENATED, is a very fine material.
It must be kept oxygenated though, so don't fill the tank to the brim or the water may get oxygen-depleted. Let is slosh about in there and make sure the breather is clear.

[MacGyverRI]

Why not use a premade flexible tank? I'm going to get the triangle shaped one, $85, 31 gals and it will sit under the V-Berth right in front of the 20 gal. flexible holding tank.

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