Ama Ballast Tank Considerations

About a third of the ama volume will be taken up by twin ballast tanks.  The ballast water is held by the hull and decks directly instead of in discrete tanks. This will probably be one of the most abused areas of the boat.  The tanks will rarely be completely dry.  Instead they will be more like a hot, humid washing machine bouncing across the waves. It's pretty important that these tanks are completely waterproof.

Gougeon has published some Guidelines for Wood/Epoxy Composite Tanks.  To summarize,

• Tanks should have 5 or 6 coats of epoxy
• The epoxy should be slightly resin rich to reduce microscopic amine deposits trapped in the cured mix.  The amine could act as a tunnel for water.
• The tanks should be post cured to at least 120F for 4 to 8 hours.
• Care to avoid amine contamination should be taken in mixing and cleaning cured surfaces.

Since this is non-potable water, I am planning on using 422 Barrier Coat Additive in the last couple of coats.  I could not find much information on 422's effects on bonding strength, so I will hold off on using it until the ama has been assembled.

The panels are currently up to four coats on the interior and are about ready for assembly

First Epoxy

I applied a coat of epoxy to some parts that don't get any fiberglass.  Start small.

Above are interior parts that form part of the pod/bunk area.

This is one of of the forestay bulkheads that will get three layers of carbon at the top, but is only coated with epoxy at the bottom.  You can see tabs/ears that will anchor the bulkhead to the main hull panels.  The notches are for spruce stringers.

Besides these parts, I spent most of the day sanding small pod/deck inserts.  These parts will be embedded in the foam core cabin top to support deck hardware and winches.  They are small bits that were nested in with much larger parts.  I decided to get them sanded and then I'll store them in bags until much later.

It has been ranging from the mid 20s to the mid 30s in town.  The heaters have been cranked up to get the shop up to 60F. The shop humidity is about 45% and a few couple larger panels on the top of the parts stacks are arcing slightly.  I'm trying to weigh those down.  A wood stove would probably drive the humidity out better.  The panels have been moved about five times in the last two weeks and have been in five storage areas.  The best storage was in Russell's shop for a few days.  He has excellent flat tables and a large wood stove.

Task Time: 6 hours

Project total time: 28 hours