Sunday, November 30, 2008

Two more F-22's launched

Ian Farrier has posted pictures of two more F-22's launched in Australia and the Philippines.  The pictures can be seen here.

I suspect we will see more Farrier trimarans coming out of Melvest Marine.  If you check the link to their web site you can download a pricing spreadsheet for your very own F-22, if you want. Anyway,  I am still waiting for good pictures of an F-22 sailing hard with the screacher flying from the bow pole.

Work on the rudder is going well and I should have an update very soon. 

Sunday, November 23, 2008

Bobstay bow eye

My family finds the name of this part interesting.  Say it three times really fast.  

Kidding aside,  I take the function of this part very seriously.  This bow eye has to take a substantial part of the load that will be created when the screacher is flying from the bow pole.   The bobstay holds down the bow pole and is connected to this eye which is mounted fairly low in the bow of the boat.   Knowing that I will probably like to drive the boat pretty hard I want to do a good job on the part.  It's another one of those parts that reduce the amount of metal in the boat and requires the use of carbon fiber.

I was able to make the part entirely from cut-off and left over material.  Above is the initial foam core that I artistically created from one piece of foam cut out from the daggerboard core.

The actual bow eye is made from a simple mold, tape and two pieces of foam and some high density putty (Cabosil and epoxy resin).  

I found that cutting and applying  the narrow strips of carbon interesting.  The unidirectional is made by knitting together bundles of carbon fiber strands  in parallel.  It was impossible to keep the knitting together with a cut of the stitching every 5 bundles, so the wrapping consisted of gathering up 5 individual bundles and wrapping them around the bow eye.  The two plastic plates really helped to keep the bundles in place.  

Final covering with the s-glass cloth was also quite challenging.  I have to admit I finally resorted to using a stretch  plastic food wrap to keep the cloth down.  I saw this hint from a post to the buildersgroup by Andrew Cuthbert.

I used a small piece of G10 tube that was cut off in making the rudder mount to help make a solid bow eye opening.  I plan to lash the bobstay synthetic rope (no shackle) so I also tried to  'bell mouth' the opening as I do not think that synthetics like a tight radius.

Don't think I can put off working on the rudder any longer.

Saturday, November 15, 2008

Rudder Mount

The rudder mount went together pretty smoothly although there are many steps involved.  Below are some pictures I took at various stages of the part fabrication.

The gudgeon mold worked out pretty well.  On the first part some of the thickened putty leaked around the G10 tube.  So on the second part I made sure some of the glass reinforcement was pushed up into this area.  This fixed that problem.  I used a little hot melt glue to keep the foam in place.

I removed the parts from the mold when they are not fully cured.  This is not just impatience.  I like to use a knife to clean up the part ,cut off the flashing, etc.  This is harder to do when its really hard.  

The molded gudgeons are wrapped in carbon fiber for strength.  I only have 9oz carbon unidirectional so I had to increase the number of pieces to get to the correct total weight.  Only issue I had was in keeping the many layers on top of each other.  But all is good in the end.

The finished gudgeons are then glued into the foam web.  I found that a tightly fitting wood dowel was sufficient to keep the two parts aligned and clamped into place.  

The part is then wrapped in fiberglass.  I used a number of pieces of the s-glass cloth.  It is pretty drapable and I did not have much of a struggle to get everthing covered.  I just prefer to make sure that the part and the cloth is wet with resin before performing my hand lay up.

When the covering is still green and tacky to touch I applied the remaining reinforcements as per the plans requirements.  I had no peel ply on hand so there is probably a bit more resin in this part than needs be...

The finished part weighs 1.27 lbs. It's  not really that pretty but most of it will be buried under the cockpit floor.  

Now it looks like I have to start thinking about the rudder fabrication.  This will be a bigger job.

Wednesday, November 05, 2008

Winter is for building smaller parts

Well, I did have to get the primer parts (the paint) warm using a pail of hot water, but I was able to finish off the port side float to the same point as the starboard float.  They will both need sanding, perhaps more primer - then the topcoat.  After that they will just need the hardware.

I've now covered them with a plastic sheet and tarps for winter.  Hopefully the winter will not be like last years - way too much snow!  But the good thing about storing hulls in your back yard is that you can watch them closely.  There will be no snow loading on these hulls allowed.

So now with the floats tucked away I can concentrate on winter work.   My overall plan is to have as much of the smaller parts done before the main hull is started in the spring.   Here is a quick list of work that I am starting to think about.
  • Finish fairing and painting the daggerboard.
  • Work on the rudder, rudder case and all the associated parts.
  • Main 'pop up' cabin top.
  • Finish laminating all the flat panels.
Hopefully the main hull will go together like a kit.