Howard wrote:
It would be a time consuming and expensive process, but nothing compared to the cost of buying a factory made mast. I'm not enthusiastic about the telescoping mast being built with straight sections. It's main virtue is that the construction is simple. I'm not sure how one would extend and retract it.... looks complex to me.
H.W.
It seems that the processes to build a DIY carbon mast to be almost not worth the effort over the more conventional mast construction methods, especially the system which has now been used with success by some builders such as Annie, that is an aluminum lower mast with a timber constructed top mast sleeved into the lower section. I have been working with carbon fiber quite a lot recently making up fittings for my little catamaran. It is difficult to wet out thoroughly, which is not so much a problem on small fittings, but could be catastrophic on a mast resulting in resin starvation in part of the mast, which will of course result in mast failure. The correct way to construct items from carbon fiber is to use either vacuum bagging, or compression moulding to ensure thorough and even wet-out of the cloth.
David Tyler made up a set of carbon battens, and a carbon yard for Tystie when he was staying at our place a few years ago. These battens were made out of double bias carbon sleeves stretched longitudinally over a mandrel, which produced almost longitudinal fibers. The mandrel was removed from the cured battens using our four wheel drive SUV, so it was real farmyard boatbuilding. David had some failures with his set of battens on Tystie due to dry spots in the lay up, but there have been no failures on the battens for Footprints after 9 years of use, and numerous hard gybes. Although the battens on Footprints were of a larger diameter than the ones on Tystie, so that may have improved their strength.
So I wonder whether the same carbon sleeves could be used to construct a carbon mast, but the sleeves are still quite expensive to purchase, and this method would not allow for taper.
I have some friends who successfully built freestanding carbon wing masts for their 56 foot catamaran. That was a DIY job and has been very successful with the masts still standing after 18 years and the catamaran having made many ocean crossings and spent the New Zealand summers as a charter yacht. These masts were made inside longitudinal female moulds with a moulded flange on the front and back of each half. Then when both sides of the mast were completed the two halves were glued together along the flanges. The layup of these masts was engineer designed. But I wonder whether this method could work for a junk mast as a taper could be achieved. So that is two half moulds, lay up each side of the mast from longitudinal carbon fiber, and then glue the two halves together. But once again it would be best to have the specifications of the layup engineer designed to achieve the correct layup for the required strength, otherwise there is a good chance of a mast breakage.
Even using this method it would be well worth doing a careful cost/benefit analysis because I think the cost of carbon and resin for say a 9 meter length carbon mast could quite easily exceed the cost of materials to build an aluminum and timber composite mast, and so if there was no significant gain in weight reduction, and guaranteed strength, then it probably is not worth the effort and expense.,