Rather than buying off-the-shelf fuel tanks, we build ours from marine ply and epoxy — giving us full control over the size, shape, and quality of the tank.
Why build your own
There's always the question of what kind of fuel tank to fit: buy a ready-made one and build the boat around it, or have one made to fit the boat? And what to make it from — mild steel, stainless steel, plastic, or flexible rubber?
Here at Epoxy.ltd and Black Bear Boating, we use another option: building tanks from marine ply and epoxy resin, using MAS Fuel epoxy. This gives us maximum capacity for the space available, and lets us control both the cost and the quality of the tank.
Building the panels
We start by coating the area to be used with MAS Low Vis epoxy, then follow with a second coat of MAS FLAG, a thicker resin with dissolved fibres already built in.
Once that's done, we cut the tank panels from Super Ply — a better-quality ply than standard marine ply. These panels are coated and clothed using MAS Low Vis resin and hardener with 450 biaxial cloth. Once that's cured, we apply three layers of 450 biaxial cloth, soaked out with MAS Fuel epoxy and rolled in with the help of a hot air gun.
For the mix ratio of MAS Fuel epoxy, get in touch via our contact page and we'll talk you through it.
We then glue the panels into place using MAS Fuel with Workshop Mix.
Fuel tank panels with the first coat of cloth and fuel resin applied
These panels go into our glue house and cure at 25°C for 24 hours.
Once we're ready to glue the panels in place, this gives us the tank body, minus the lid. Both the diesel and water tanks on the schooner will have baffle plates fitted inside to reduce sloshing.
Making baffle plates in-house
Epoxy and cloth panels like these can easily be made for a wide variety of projects. They're very strong, and they don't rot.
We use an old flat door with a couple of coats of gloss paint as our work surface, waxed with ordinary shoe polish spread out with a polishing cloth. We always go a good 2 inches past the edge of the cloth, and cut the cloth larger than the panel we need, so we don't push epoxy to the edge and waste it.
We lay the first layer of cloth onto the wax — this layer may get sanded away later, depending on how the wax penetrates as heat builds up from the epoxy. The next layer uses 450 biax cloth. We mix up the fuel epoxy and, using a heat gun and roller, pour it on and roll it in while the surface is still wet, laying cloth and rolling on a layer of epoxy for each one. Depending on what we want the panel for, we might roll one layer (around layer four) dry with the hot air gun to soak up any free epoxy, then continue with epoxy and cloth until we reach the thickness we need.
Note the paint that came off the table when we made these — these baffles will get a sand and another coat of MAS Fuel epoxy before being fitted into the tanks.
We let this set overnight, and prise the panels up the next morning — you'll often find bits of paint peel off with them, but don't worry at this stage. The unfinished panel then goes somewhere warm to post-cure for 24–48 hours, before being trimmed to shape with a diamond or stainless steel cutting blade, sanded on both sides, and given a final painted coat of epoxy before being fitted into the tank.
These fuel tank baffles will have a sand and another coat of MAS Fuel epoxy before being fitted into the tanks
What's next
The next step is the tank tops, which will have 1.5-inch copper feed pipes, a 28mm hand pump to the day tank, and a 10mm electric pump line to the day tank. There's no gauge on these tanks, but there are two 10mm lines out — one at the bottom of the tank, and one about three-quarters of the way down. The higher line is our main draw; when it draws air, we switch a three-way valve to the deeper, reserve outlet, which tells us it's time to refuel. We're waiting on parts for this, so they'll be along soon — virus allowing — and we'll post pictures when they're fitted.
