I'll be installing the optional aux fuel tank in my 2005 Seafarer 228 and an looking for a source for the HDPE brackets used to secure the tank. Anyone know who the OEM was or know of a viable alternative?
Pressure treated wood is the least suitable choice you could have made I am sorry to say. The chemicals in the wood will leach out and can cause damage. In addition, the wood may rot leading to structural issues.I have just finished fitting the auxiliary fuel tank to my 228. I couldn’t find any HDPE blocks big enough here (Australia) to make mounting brackets from. So I ended up using treated framing pine. 2 pieces that span the width of the tank to the walls of the compartment. I screwed blocks to each end of the 2 pieces that fit in the gap between the tank and wall. These were the screwed into the compartment walls.
I used 3/8” x1/4” strips of fibreglass stuck to the tank with 5200 to raise it up from the floor and between the timber and the tank.
It doesn’t look as clean as the HDPE brackets but it is just as effective.
The 10 gallon water tank is secured with pine and it looks like new even though it's almost 20 years old. I know it's original because the only holes in the compartment wall are the three holes for the mounting the pine.Pressure treated wood is the least suitable choice you could have made I am sorry to say. The chemicals in the wood will leach out and can cause damage. In addition, the wood may rot leading to structural issues.
Marine grade plywood would be a better selection but still not great. In your local box store, you may find sheets or fiberglass reinforced panels. That stuff is often used as 'paneling' in wet and or sanitary environments. It will be thin and must be layered with 5200 between the layers to get the appropriate thickness. As already mentioned, PVC stock like Azek would also do. The PVC would be easier to use for brackets an d the FRP strips are better for the under tank strips for setting the tank onto.
There is a saying that 'Perfection is the enemy of good enough" and a couple of years ago I wouldn't have even considered using timber. I was firmly in the "do everything the best way possible' camp. Try to mitigate every foreseeable problem.Generally speaking, PT wood vs aluminum = PT winning the fight. But since you are separating the two with a barrier you'll be fine.
To expand on this... using PT wood as carpeted bunks on a pontoon trailer leads to the Al corroding. But this example keeps wet PT wood (carpet holds water) in contact with the Al. You shouldn't have this issue.
That said, personally, I would have still used non PT wood just to be safe but I do think you'll be just fine.

Nothing touches the tank directly. Everything sits on fibreglass strips adhered to the tank with 5200. Anywhere that the strips were adhered to was scrubbed with scouring pad, wiped down with acetic acid and then cleaned water and dried to ensure a good bond. If I could have sourced large enough blocks of HDPE I would have used that but I couldn't find any.Perfection isn't that much harder or expensive to achieve. And you will sleep better. Done right - done once!
Tanks should be insulated with nitrile strips glued to the tank with 3M4000. I also insulated the mounting pads. Water trapped between the tank and whatever is the securing material will promote corrosion. Properly insulated you could get away with wood but I used original HPDE block. Remember - nothing against the tank that isn't attached to it!
GW used neoprene self-adhesive strips as an insulator. Easy for the factory. Over time these strips come loose and trap water against. Look at aux tank photo below. You can see how the strips wiggled and the white corrosion spots on the tank.
The HPDE blocks are likely made in-house by GW. If you have a table saw you can make them yourself. Buy a piece of of HDPE online. I can probably get you dimensions. GW Customer Service may be able to give you a drawing.
When installing the blocks use a Torx head stainless screw as shown. They drive in better and if you have to take one out you can thank me later!
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Sounds good. Sourcing things is a little different down under!Nothing touches the tank directly. Everything sits on fibreglass strips adhered to the tank with 5200. Anywhere that the strips were adhered to was scrubbed with scouring pad, wiped down with acetic acid and then cleaned water and dried to ensure a good bond. If I could have sourced large enough blocks of HDPE I would have used that but I couldn't find any.