Interesting former stations on this cat build. What are all the holes? Notice nice examples of different foam densities for different loads, and wide planks on the flat parts.

Here is a carbon fiber hinge, built by Russ Brown, that I got to touch. It must weigh a couple of ounces, and be at least 4 times stronger than A36 steel. Of course it makes no sense as carbon is most useful for deflection driven parts. But you can prove that you are one of the cool kids with these. These are like the chocolate chai caramel vanilla hazelnut white mocha caramel sauce classic syrup mocha cookie crumble frappuccino of coffee drinks.  These are the definition of yuppie.  What do you suppose they cost?  $100 each?  $500? I wish I had some.

I got to catch up with old friend and boat building legend Roger Hatfield today.  I had one insight before the meeting.  I often am critical of shoddy designs and/or shoddy engineering.  I have heard it put up to resentment or something else.

Be clear, I have probably lost more jobs to Roger than anybody else.  But he does great work.  I have never seen anything to be critical of. Thats the difference.  He is in town working out the build of a new Bieker 50′ something cat.  The design fee will be at least $100,000.  And I hear so much whinging about my design fees.

OK I have not had chance to update plans prices yet. Its been all week on plans support.
Next week.

I was sent this link for less costly foam core. It is in UK so not local for many people. And the range of sizes and densities is minimal. I have not yet studied the data. Maybe someone has experience with it.
http://www.easycomposites.co.uk/Category/Core-Materials/Closed-Cell-Foam-and-3DCore.aspx

I see my friend and my structural engineer David Jones is a rock star in Pro Boat magazine this issue. Cool. I’ve known David since the 80s at MACAM conferences.  David always understood that my customers wanted the engineering without having to pay for it. So I would do the calcs in Excel typically, send to him, and he would agree or not. See issue #149.  David knows things.

I have been advised on the steamradio multihull blog to keep quiet when I see some preposterous assertions made there by famous designers. I always think that someone will say something; lots of the guys there seem to know things. But it rarely happens.

One really stuck in my mind though.  A few months ago Kelsall noted that he uses 30% carbon fiber in his wing masts. I kept waiting, but nobody questioned him on that. So maybe school has to be in session.

First, surely everybody knows that a long, slender composite part like a wing mast must have at least 70% of the fibers in 0 degree.  Ted van Dusen noted to me when he built a couple of critical masts for my boats, that had to be built with too small diameter, he went to 80% in 0 degree, just to be sure. 

OK, so if all the 30% carbon was in the 0 degree, that is still less than half the 0 degree fibers as carbon.

That is bad, bad, bad.   My readers all already know that the stretch to failure of carbon fiber is around 1%.  And that of E-glass is around 6%.  The carbon in the wing mast would have to fail completely before the glass even helped with 20% of the job.  I was dying to know; did he not believe in 70% zero degree? Or in rule of mixtures.  Getting everything possible right the first time is important.

Ron Reichard explained that with carbon in the 0 degree, glass can be used in the off-axis fibers. That lowers cost and even adds a bit of resilience.

I will have more on wingmasts next month, including a study that I co-authored with Dr. Paul Steinart on a FEA study of wingmasts, and composite hounds.

I have an ancient Universal Plastics catalog. It is full of all the data on every kind of plastic. They are now called Laird Plastics and the catalog now is only online. But they still sell everything plastic. 60 locations in US and Canada.

http://www.lairdplastics.com/