Thursday, September 24, 2015

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

Thursday, September 17, 2015

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

Wednesday, September 2, 2015

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