Bob posted the following in another thread. I thought I'd move the discussion to an appropriate thread and ask a more direct question.
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Checking Harken.com's Compuspec "load report", the sheet load on the Genoa in 20 knots is 507 lb and 1355lb on the #3 in 40 knots, with an end boom load of 1818lb. That's 1/7, 1/3 and 1/2 respectively of the 3800 lb tensile strength of 3/16" Spectron 12. Figuring 100 feet from Layline, Spectra is $55, Technora $70 and Vectran $83, it's hard to justify the additional cost for the extra performance. Spectra is a bit lighter and there is no concern about UV. Creep, the supposed Achilles' heel of Spectra, has not been a problem, though we do regularly adjust halyard tension when racing. We've had the same jib and main halyards for over four years and they were pulled only for one winter. Ours are covered only at the clutch; before you locate the covers, be sure to consider that the luff of the #3 is 2'3" shorter than the #1 and you might reef the main! We use covered Spectra for the spin halyard and sheets for ease of handling.
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Good information. Does anyone know what the actual design loads are for the halyards? Or, just as good, does anyone know how to calculate the actual loads? I'd like to pick the right size lines based on actual design loads for the halyards rather than use loads from Harken that are for sheets and blocks.
Alan Grim
J30 #359 JayHawk
