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. 

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.

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.

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.

Hull preparation - my best techniques summary

This post is mean't to be a notes to myself for that time 'hopefully' in the not to distant future, when I am preparing the main hull.  It's also a post for others with the following label.  'Every amatuer builder is different and the best techniques for one builder will not be a good fit for another.'  

1) Lay up the foam as fair as possible.  Use the polyurethane construction glue (the stuff that does not expand that much) so that the outer hull can be immediately sanded without any hard spots.

2) Always wet out the foam before laying any laminate.  I have found that this is absolutely required with the fine weave aerospace cloth that I am using.   

3) Always use peel ply when doing any hand lamination.  Using plastic sheet over the peel ply is a good way to ensure a good result.  When squeegeed the plastic creates a local vacuum (for good adhesion) and allows you to remove the excess resin.  I may be at the point of not bothering with vacuum bagging as I fail to see any major benefit for all the extra trouble and cost.

4) Apply fairing compound sparingly and sand most of it off.  Good results were obtained with Quickfair.  Sand, sand and sand with the long board (60 grit) until there are no low spots left.  Where possible make sure the bare laminate serves as the local high spot for the long board.  

5) Apply skim coats of epoxy resin to seal up the fairing compond and fill the pinholes.  Sand with the orbital sander (no more hand sanding, except for the hard to get at places), with 120 grit until the hull is smooth.  Smooth is when the surface is all smooth and dull with no shiny spots.  It's okay to apply more fairing compond at this point, this is the last chance.  The thin first primer coat will seal it.

6) Apply the bottom paint.  Thinking ahead, do a good job with a manometer or laser to get the designed waterline right on the main hull.  VC Performance Epoxy can be rolled on.   At least 3 coats.  The  surface can be wet sanded as smooth as required.

7) Apply the topcoat finishing primer with a foam roller.  With Endura EP-2C primer sealer thinned 15% air bubbles are not a huge problem.   I have been waiting till it is fully cured then sand with the orbital sander with 220 grit until the hull is smooth. 

8) Unless an excellent method for applying the topcoat is found, take the hull to a paint shop for topcoat spraying.  

No topcoat painting for now

The weather was recently quite nice, low humidity and pushing 20+ degrees C,  so I decided to apply a coat of Endura topcoat on the outer half of the starboard float.  I used a foam roller and tipped out the air bubbles with a brush.  Making a long story over a few days - well short, I was not happy with the result,  so I sanded this coat down to 220 grit.  It is now very smooth but dull.  So ...I have decided to leave the floats for the time being with the finishing primer on the hulls.   Maybe I will have a professional paint shop apply the final topcoat when I have all 3 hulls ready.  

Winter is fast approaching and I hope there is  time get the port float all sealed and primed as well. 

Update: We weighed the starboard float today, it looks to be ~ 125lbs as is.

Finishing primer on the starboard float hull

The skim coats of epoxy seemed to work really well at providing a very fair smooth surface after sanding.  Fair enough, and I decided to hang the hull once again and apply the finishing primer to the whole hull (excluding of course the bottom paint which I masked off).  I applied the two coats of  Endura EP-FD primer with the foam roller and found that with the doors open I was able to get by with the half face respirator.  I think flowing on the paint is far less dangerous than atomizing it with a spray gun.  Quality wise I think rolling on the paint when the hull is hung like this is not optimal, I do have some paint runs here and there.  However since I will be sanding this primer down to 320 grit, I thought that getting it all painted was more important.  However, when I get to the topside paint I think I will be painting the hull in sections (roll and tip) , ie on one side, the other side and then the deck.   If anyone is interested I found a very good tutorial (for Sterling paint) here.

Below are a few pics of the now white primer coloured float hull.