The Goat has a balanced lug sail. This is a bit different from your typical mast and boom arrangement in that the top or head of the sail is held up by a stick called a yard. It's somewhat like the top batten on a modern square head main sail. Just not nearly as high tech.
Here is the designer, Michael Storer showing off the lug rig:
The yard should be made of strong, light wood like Douglas Fir. I could not find a suitable piece locally but did find a nice piece of Cypress. I found out later that Cypress has a tendency to warp when cut so it's not the best choice for a long straight stick. I must have gotten lucky because this piece remained straight after ripping to size. I ripped the final piece in two and glued the two pieces back together with the grain reversed. This should prevent any warpeage in the future as the two pieces will fight each others warp.
You can't really tell in the pictures but the yard is tapered on both ends. The designer provides offsets at measured intervals to define the tapers. After laying the taper out on one side I ran the yard through my little band saw. Then I rotated the yard 90deg, marked the taper on one of the cut sides and cut to shape. The resulting tapering square cross section is planed to an octagon and then rounded. I did not round the yard in order to make it a bit stiffer to compensate for the Cypress being a bit more flexible than the specified Douglas Fir.
The sail maker needs to know the bend characteristics of the yard in order to build the proper shape into the sail. The bend measuring procedure involves hanging a weight, in this case 35lb, from the center of the yard and measuring the amount of flex relative to a string line. Measurements are taken at 3 points along the yard since it's tapered and therefore bends unevenly along it's length.
As with all pieces, the yard gets 3 coats of epoxy. The #*@!! contaminANTS (thank you Doug) were out in full force while the epoxy was curing.
Total time to date: 152hrs
No comments:
Post a Comment