Subject: [harryproa] Re: Rotating Carbon Fiber Mast
From: "Robert" <>
Date: 7/18/2007, 9:56 PM

My thoughts are to avoid aluminium as it is heavier than the
equivalent in either carbon or even strip plank. There is also the
difference in expansion coefficients and the possibly of the aluminium
producing enough oxide to jam the system if left too long. All of the
concept could be done with either strip planl or carbon with less
bonding difficulties.
--- In, "harry_tomlnson"
<harry_tomlnson@...> wrote:
> What's a good method to home build carbon fiber masts? Also, for a
> freestanding and rotating mast, what's a good design for the
> bearings/embedment. My specific interest is in a freestanding
> rotating rig with a wishbone sprit boom with about a 25 foot tall
> (7.5 meter) mast on a boat with a max righting moment of 10,000 ft-
> lb (1380 kg-m). The hull depth for embedment is about 2.5 ft (0.75
> m). I figured this application would have some similarity to a uni-
> rigged Elementarry.
> Is there a free, written description of the Harryproa strip plank
> carbon tow method I have seen reference to?
> For those with experience, do you think the following idea has
> merit? Use a structural aluminum pipe (T6061 4-in schedule 40) for
> the lower section (say 2 meters long), overlay a thin plywood or
> strip plank wood core overlapping the pipe (say 1 meter overlap) and
> hand lay-up the carbon fiber/epoxy composite with a combination of
> biaxial and uniaxial cloth. I have thought through the details of
> this process, especially how to get the wood/carbon/epoxy to hook up
> real good with the aluminum stub, but I won't try to explain it
> here. The aluminum stub would then insert in a high density
> polyethylene (HDPE) pipe solidly attached to the hull framing. The
> HDPE would therefore be the bearing material. I wonder if this
> embedment gives too much friction for rotation.

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