Subject: Re: [harryproa] carbon tow
From: "Rob Denney" <>
Date: 7/25/2007, 10:44 PM

Three years ago, when the carbon squeeze started, it was all going to be over in 6 months as new production lines were built to cope with the upsurge in demand from Airbus and Boeing.  6 months later it was even harder to get carbon and the response was the same.  Zoltek has qaudrupled production, as have the other manufacturers, and the story is still the same, with a different culprit;  6 months once we have enough capacity to meet the demands of the wind power industry.    I suspect that it will be a while as new uses are continually being found, for example, carbon is slowly moving down from the ultra high end of  the automotive industry, the construction industry is already using carbon for reinforcing concrete and repairing bridges and deep water oil rigs are using it as mooring lines.  The answer to your question is, your guess is as good as mine.   
A harry mast requires 30 kgs/66 lbs of tow, the beams 15 kgs/33 lbs, the boom 10 kgs/22 lbs and the rudders 10 kgs/22 lbs.  Total 65 kgs/143 lbs.  If you plan to build some all all of the carbon components yourself, the price ex Abilene Texas is $AUS38.25/kg approximately $US15/lb.
It looks as if a KSS hull will be lighter than a cedar one. It certainly should be in theory.   It also looks as if the labour and materials costs are far less.  We have not done any real numbers on this yet, but it is based on the following:
1) Vinylester is less than half the price of epoxy, polyester is less again
2) Foam and cedar are about the same price, depending where you live. There is little or no waste with the foam.
3) There is a little more glass in the foam boat. (12 sqm of uni @ $5/sqm in the solo boat lee hull)
4) Gel coat is a small fraction of the price of primer and lpu paint. 
5) The only fairing is below the waterline, making a big labour saving over filling, fairing and painting a glassed hull, and savings on bog and sandpaper.
6) Infusing the first hull half takes about 3 man days (it will be quicker with practise), each half takes one man day to shape and glass below the waterline.  This is pretty much regardless of hull size as most of the work is setting up the bagging and infusion material.  The deck is another 3 day operation, which is additional to a strip plank boat, but is largely made up for by the ease of not having any blind joins when assembling the hulls, due to the deck edge radius.
Layup of the hull is one or  two layers of 450  double bias glass either side of the foam, with strips of 450 uni glass as required.  No carbon or kevlar required. 
As far as I can see, a foam glass boat is every bit as strong and seaworthy as a wood/glass boat.   There are plenty of examples of both that have been sailed hard with no problems.  Hand laid glass/foam boats often have bonding problems between the core and skin, as air is trapped in the open cells on the face of the core.  This is not a problem with infusion.  
You should have no trouble keeping up with the F boats as long as you are not overloaded. 
Any other questions, please ask.  If you do want some tow, please let me know asap as I will be ordering next week.  

On 7/26/07, George Kuck <> wrote:

Hello Rob,
Did you get any indication when the availability will be getting better, in another year or two?
How much is needed to build a mast for the 40' Harryproa and are there other alternative sources or material options ?
I am considering building a 40' Harryproa using the KSS method but it will be at least another year before I can start.
Do you also use carbon fiber in the hulls or beams ? Will you be able to maintain the light weight using fiberglass foam core with vinylester resin (I dislike epoxy except were absolutely needed in mast or other high stress parts) or will it be necessary to use carbon fiber or Kevlar ? What would the typical layup consist of for the hulls ?  My main concern would be to keep the cost down while at the same time building a reasonable good performing (light weight)  and seaworthy boat for cruising. It will not have to be a all out racing boat, but would be nice to be able to keep up with a F-boat if possible ! 
George Kuck
Chestertown, MD 

Rob Denney <> wrote:

I have just received sponsorship of the solo Transpac boat from Zoltek,
manufacturer of carbon tow,  which is our preferred material for mast
building.  For the last couple of years tow has been impossible to obtain,
and the situation is no better now.  However, as part of the sponsorship
deal, Zoltek will supply me with one order, as much as I want, for my boat and others,
at a very good price.

If you are interested in buying tow for your boat or mast, the cost is
$AUS45/kg plus local taxes.  If we are going to build you a mast, we are
happy to stockpile it for you until you are ready to start.  If you do not
know the exact quantity, we will buy back any that is left over.

If you want it delivered anywhere else, please let me know and we can
discuss a price.

How good a deal is it?  Uni currently costs $AUS100 per kg, is time
consuming to cut, and on tapered masts, wasteful.

Any questions, please ask.  It would be good to place the order within the
next  week.  Delivery is another 6-8 weeks.

Any questions, please let me know.



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