Looks like a comparison test in the making.
How about it? Maybe one if the Fin Delta owners could supply you with one.
I’ll leave the testing and comparing different riding sails to Practical Sailor. Actually, I don’t know how it could be done. I have been using this one for three years and have been watching others use their riding sails for longer than that. Here are some thoughts:
What is the ‘measure of merit’? What is “better”? I chose to visually compare graphs of the variations in the apparent and true wind with and without the riding sail hoisted. Others might be interested in heading variation, changes in boat GPS coordinates, chart plotter tracks, or something else.
How much weight should be given to any increase in anchor load? I know that when I hang my sun awning vertically behind my bimini to shade the cockpit in the evenings, the swinging of the boat diminishes, but no doubt the anchor load also increases. After all, the awning is just a square sail pulling the stern of the boat downwind. I imagine that, compared to a flat sail, a dihedral sail has some increase in average anchor load. Is that important?
What about cost and simplicity? How much do they matter?
What about the boat? I have a 34’ Pacific Seacraft with a canoe stern. The backstay comes down at the pointy stern of the boat and there are no easy spots to tack down the two corners of a dihedral sail. Other boats like the Beneteau/Jeanneaus with their wide sterns or boats with huge stern arches have perfect places for attaching the two tacks of a dihedral sail.
How much does the boat swing on its own? Those same Beneteau/Jeanneaus with their masts set forward move around a lot. Some of the catamarans anchored with a wide bridle don’t seem to move at all. Obviously, not all boats act the same without a riding sail. Perhaps the same is true of boats with a riding sail.
What about the effect of current? Many times, we find ourselves anchored with the anchor chain leading off to one side of the boat or on occasion even back under us. It never looks like that in drawings in books or magazines, but it happens. Sometimes instead of just swinging back and forth, we go in circles. Other times we just fly like a kite off to one side of the anchor. How does the riding sail effect the boat when there is a current flowing?
How much wind should be blowing and how rough should the water be while the riding sails are being tested and compared? I know from my own experience in wind to 30 kt and waves to 2’ that it does make a difference in both the anchor load and in the boat behavior. A gusty wind is different from steady wind, and wind that swings back and forth is different from wind that blows from a constant direction. When strong winds are forecast, we shelter behind land. That is a guarantee of gusty, shifty wind.
Anyway, if you want me to test a dihedral sail, box it carefully padding it with wadded up $100 bills and have it sent via Watermakers Air of Ft Lauderdale to me c/o Staniel Cay Yacht Club. I’ll get right on it.
1988 PSC 34