Line Load Litigation

[lavery]

Riggers,
It appears that neither New England Ropes nor West Marine want to venture recommendations for sailboat running rigging applications. Fair enough. They may prefer to avoid ever seeing a lawyer show up at their door as a result of their recommendations.

So I am grateful for Brion’s “Rigger’s Apprentice” (the textbook for this note) for providing charts, graphs, formulas, techniques, material descriptions, and product reviews to guide me toward my rope purchase decisions. (..end of testimonial..)

(..intro to question..) Using Harken and Lewmar formulas and chart, and rounding up to the nearest 500 pounds, I landed at 2,000 pounds of force for mainsheet loads. New England Ropes wants me to multiply by a safety factor of 5.

(..the question(s)..)
*What is the range of mainsheet diameters that feels comfortable to your hand?

* I want to use 3-Strand Nylon for the mainsheet for its shock absorbing ability. Would anyone hesitate to use a 7,500 pound nylon mainsheet (1/2” in chart below) to manage nominal 2,000 pound mainsheet loads?

*Finally, for halyards, my sense is that they are subject to far lower shock loads than sheets. My halyards calculate to 1,500 pounds (per Lewmar). What safety factor would you apply to halyards?

Happy sails to you,

Jim Lavery
s/v Hoku Ke’a
Southern Cross 31 cruiser, displacement 13,500 lbs.

New England Ropes 3/8" 1/2" 5/8" Stretch @ 30%:
3-Strand Polyester 7,500 11,700 n/a n/a
3-Strand Nylon 4,400 7,500 12,200 13.0%
12-Strand Single Braid Poly 4,500 7,500 11,000 4.5%
Double Braid 4,400 8,500 14,400 3.5%
Double Braid Parallel Core n/a 5,500 9,600 2.8%