I have a O'Day Daysailerand wish to know what other owners have done as far as placement of blocks for the spinnaker sheets? I was thinking of adding another t track with sliding block on each side about a foot forward of the transom. Any help would be appreciated.
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B
bruce cornell
spinn blocks
on my javelin, they are located near/ just ahead of the stern cleats. being a class boat, there is no specific placement for them in the rule book. sliding block may be overkill due to small size of spinn and block location so far aft of the mast.
on my javelin, they are located near/ just ahead of the stern cleats. being a class boat, there is no specific placement for them in the rule book. sliding block may be overkill due to small size of spinn and block location so far aft of the mast.
R
Roger
spin sheet block placement
I placed my spin blocks a couple of feet forward of the transom on the outside of the coaming. I used eyestraps and mini blocks, because the forces are so small. I also used 1/4 inch line to keep the weight as low as possible.
I placed my spin blocks a couple of feet forward of the transom on the outside of the coaming. I used eyestraps and mini blocks, because the forces are so small. I also used 1/4 inch line to keep the weight as low as possible.
very little pressure
I can usually hold the spinnaker sheet with thumb and forefinger, the pressure on the sail is so little. The eye strap would all be under sheer stress at the screws, so it is very little indeed. I did not use any backing plates. Doing the math, the maximum square footage on my chute is 85# based on the accepted theory that the maz wind resistance is based on the pound per square foot ratio. With my chute being 85 sq ft, the max pressure in the heaviest blow would be 85#. Divide that equally by the three attachment points taking the load (head clew and tack) and you get (85/3=28.3# on each sheet. It likely lower, because some load is assumed by the whisker pole, and for me each spinnaker sheeet runs through a turning block bevore being cleated. So if at max the turning block and cleat each took half the load, that is now down to 14#. Each of them is held in place with two screws into the fiberglass, so each screw (at max) would take a load of 7 pounds. If you hung a 7# weight from a screw embedded in fiberglass, would you think it would hold? I would suggest yes easily! In most cases, I would suggest the the loads each spinnaker sheet are significantly less that what I have theorized here. If anyone has a fish scale on board, they could actually do a test ti determine the pounds of pull on the spinnaker sheet. These numbers are limited to the Daysailer. I wold welcome any challenge to this theory, as I have yet to test it other than my finger pressure story.
I can usually hold the spinnaker sheet with thumb and forefinger, the pressure on the sail is so little. The eye strap would all be under sheer stress at the screws, so it is very little indeed. I did not use any backing plates. Doing the math, the maximum square footage on my chute is 85# based on the accepted theory that the maz wind resistance is based on the pound per square foot ratio. With my chute being 85 sq ft, the max pressure in the heaviest blow would be 85#. Divide that equally by the three attachment points taking the load (head clew and tack) and you get (85/3=28.3# on each sheet. It likely lower, because some load is assumed by the whisker pole, and for me each spinnaker sheeet runs through a turning block bevore being cleated. So if at max the turning block and cleat each took half the load, that is now down to 14#. Each of them is held in place with two screws into the fiberglass, so each screw (at max) would take a load of 7 pounds. If you hung a 7# weight from a screw embedded in fiberglass, would you think it would hold? I would suggest yes easily! In most cases, I would suggest the the loads each spinnaker sheet are significantly less that what I have theorized here. If anyone has a fish scale on board, they could actually do a test ti determine the pounds of pull on the spinnaker sheet. These numbers are limited to the Daysailer. I wold welcome any challenge to this theory, as I have yet to test it other than my finger pressure story.
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