I've successfully made a sprit sail which can rotate 360 degrees
around it's mast. The mast on a sprit sail should rotate so the
sail will set properly on each tack but getting the mast to rotate
can be a challenge. A traditional approach which sometimes works
is to line the hole in the mast partners with oiled leather.

I tried putting a sleeve on the front of the sail and using a
length of rope down the inside of the sleeve to support the end of
the sprit. This particular sleeve is open at the top with a thick
pocket inside to receive the top of the mast. I was having trouble
with the top of the home made solid spruce mast binding in the
sail pocket until I sanded it and gave it a coat of polyester
resin, and additionally cut off the top of an aluminum beverage
can and inserted that upside down in the mast pocket. The only
limitation is that for 360 degree rotation there is no Cunningham
downhaul to tension the mast sleeve. If 360 degree rotation is not
needed, and it's not to just to get the sail to set properly on
both tacks, then a Cunningham can be used. I like the 360 degree
rotation on my small boats because in a strong following wind the
sail can be let out completely to control broaching and to avoid
the dreaded oscillation called "death roll". This particular sail
is small (32 sq ft) and does not have a boom, however a sprit boom
could be supported by the same length of rope down the inside of
the sleeve that supports the sprit.

For anyone interested in making this kind of sprit sail there are
some photos showing how the sail was made at
www.ncf.ca/~ag384/TyvekSail.htm. The emphasis is on making
a sail out of Tyvek on a sewing machine. I hope to add more
information on the rotating feature presently. I still have some
minor modifications to make to improve performance and handling.

I'll just mention finally for those who may not be aware, putting
a sleeve on the front of a sail reduces mast turbulence and
improves sail performance at the cricial leading edge.

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William R Watt National Capital FreeNet Ottawa's free community network
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