Shed Happens

What do you do when you are thoroughly bored of fairing akas?  Bump out the shop extension.

I now have a 42 foot shop in which to build a 32 foot Vaka.

We also had a flying ama sighting.  Raising the hull frees a lot of precious floor space.

Task time: 16 hours

Total project time: 846 hours

Ama Flipped

A couple weeks ago I flipped the ama over and started work on the interior.  

The keel panels needed taping with two or three layers of fiberglass.  Fillets were applied to the keel seam and the bulkhead intersections.

A final coat of epoxy went over the seams and interior.  I went with West's 207 special clear epoxy resin as it contains less amine which is beneficial to the barrier coat.  Also added 422 barrier coat compound.

The ballast tanks were then post cured.   It is suggested that the barrier coat should be heated to 120F (49C) or above for four to eight hours.  I piped hot air from a small ceramic heater into the space.  If you place the the heater inside, the thermal safety circuit will shut the machine down repeatedly.  I also added two 125W infrared light bulbs.  250W bulbs are available, but I was fearful of burning things in the small area.  This setup kept the temperature between 130F  (54C) and 155F (68C).  I clamped the lights to shine on the protruding tops of the bulkheads separately.

Task time: 110 hours

Total project time: 770 hours

Ama Progress

The ama has been making good progress.  The keel panels went on.  Next the seams got cleaned up and filled where the wires had been.  The wire holes were closed.

A main task before moving on was fairing the chines, bow and keel.

Here is a bow filled and capped with a thin strip of glass.  I wanted to fully close the seam.

The bows and keel were about 20mm wide when joined.  The square shape did not look too sleek, so I decided to add a foam nose piece. The top picture show the foam glued over the glass, while the bottom is after shaping.  This is Divinycell H80.  It is strong, though I worry about cosmetic damage in minor bumps.

On the keel, I used the same concept with a strip of plywood.  The plywood has the corners on one edge rounded over.  A thin bullnose was then ripped on the table saw.  #17 finish nails are place prior to gluing.  The nails will act as alignment guide once the strip is wet.  Tape at 2 inch intervals worked pretty well as clamps.  I used fast hardener and added a little 5 minute epoxy to get the glue to stick and kick faster. This is a trick off of the West System site.  Sanding then faired it into the keel panels.

Here is the glass draped and partially smoothed.

The intersection of the bow and keel fairings.

The cloth has been wet out with a roller.  This shows how the bulkhead tabs were glued to the hull panels.

Here is the hull drying prior to the first fill coat.  The skirt will be trimmed off of the shear before the epoxy fully cures.  The skirt is also handy for catching epoxy runs during wet out.

Task time: 50 hours

Total project time: 660 hours

Ama Strongback

There has been more sanding and coating on the panels.

I had to reconfigure the shop a bit to allow storing my tablesaw to leave enough room to walk around the 25 foot ama and keep the build table in place.

The strongback is made of two engineered beams laid over stout sawhorses.  The beams are large and way overkill, but they are true and I got a great deal on them at the lumber yard.

The mounts for the bulkheads are MDF attached with 1.5 x 1.5 inch cross pieces.  I made the internal span 30 cm to allow attachment with access to the bulkhead edges next to the hull panels. 

The four inboard stations will be supported.  Two outboard stations will overhang each end.

These are the bulkheads loosely propped in place.  I'm waiting for a cross-beam laser level to arrive.  The bulkheads have the horizontal and vertical centerlines scribed on them for accurate alignment.

Task time: 13 hours

Total project time: 610 hours

Mounting Ama Stringers

Leading up to mounting the ama stringers on the hull panels, there were several tasks.

Scarfing the fir stringers.  Two scarfs per side.  25 feet each.

Rounding over the bottom edge to fit the CNCed bulkheads.

The stringer is 38mm vertically.  This was just enough heft to require some serious clamping to pull the curve to match the rocker of the shear.  I had to make up 25 of these reusable blocks to support horizontal clamping.

Stringers glued up with the horizontal clamps removed.   There was enough bend that the panel had to be set back away from the edge of the table.  This meant using screws to clamp vertically as most of my clamps don't have a deep enough throat to reach.  The holes will be filled with a syringe later.

Task time: 28 hours

Total project time: 625 hours

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

Start of the Ama

I started glueing the puzzle joints on the ama panels yesterday.  Hope to get a strong back going within a week.

Task time: 12 hours

Total project time: 502 hours