Aka Fairing Reinforcements

Applied reinforcements last week.  There are three layers of unidirectional tape down the spine of the curve.

300 gm/sqm cloth draped over beam.

The uni is visible under the eglass.  It will provide lateral stiffness.  I had to fair the edges in a bit as the stack of uni stood proud a couple of millimeters.

The glass covering physically locks all of the layers together to the main beam at the bottom.   More importantly, the glass provides a measure of toughness.  The foam with only a bit of fairing compound over it was quite fragile.  It would have been easy to poke a hole or ding it.  The fairing is now firm, but may still be vulnerable.

The second beam is now mostly shaped and the surface being faired.

Task time: 8 hours

Total project time: 854 hours

Aka Fairings

The outer edges of the aka crossbeams are covered with a foam fairing.  This will allow waves to flow past them easier as well as providing a great deal of lateral stiffening.

The foam is lightweight polystyrene building insulation that was CNC cut by Turn Point Design.

After looking around the internet, I decided to use Gorilla Glue to join the pieces of foam.  The glue is gap-filling, strong and has a similar sanding characteristic as the foam.  Above, is a test glue up.

The foam is carved into sections that are stacked.  Every few feet there is a half ellipse template for a fairing guide.

At the windward end of  the beam a solid piece of wood will be attached and shaped. This strengthens the end where is will be attached inside the ama.

Once all of the sections are fastened in place you start sanding.  I have been using a homemade longboard that is about 3 feet long.   The foam sands best with 40 to 80 grit paper.  It is very easy to clog up sandpaper with the blue dust, so 40 is used for all of the initial work.

The solid wood end is a piece of laminated black walnut.  The initial shaping of the wood was done with a belt sander and a plane.  After establishing the basic shape it is blended into the foam with the long board.

I also built a 6 foot sanding board for leveling long sections.

There can be tearout of the foam while sanding along seams.  The picture above shows the first beam after multiple cycles of applying fairing compound and then removing it slowly.  The beam is starting to take on a pleasing shape.   The next step will be to reinforce the leading edge with unidirectional carbon.

Task time: 60 hours

Total project time: 830 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

Last Carbon on Mainsheet Beam

After a bit of fairing to level any previous layup seams, I have applied the final layer of carbon.

This is a 300gm/sqm bidirectional sleeve. The sleeve went on before wet out.  It looked pretty hard to wet it out and then slide the slimy, slick tube over the beam.  I rolled and squeegeed multiple coats on the beam, as I was a bit worried about full saturation of cloth this heavy. 

There was some creative clamping going on.  I skipped vacuum bagging to avoid wrinkling.  The sleeve can be stretched pretty tight by hand.

Finishing will require fill coats of epoxy and sanding smooth.  The worst of the process will be sanding the gathered ends to blend them into the end shapes.  

Task time: 12 hours

Total project time: 346 hours