Line Load Litigation

[lavery]

Allen & Ian,
Thank you both for your informative and very entertaining replies. Now that I have finished crunching numbers, a conversation with experienced opinionated sailors is exactly what I need to balance my results.

Allen,
Thank you for your recommendation of 7/16 Sta-Set or XLS. That is certainly in the calculation ballpark. Also your comments about line feel and running are just what I was hoping to get from this conversation.

The 2,000 pound mainsheet load is the result of heavy-handed (some might call it "conservative") use of Harken's Main Sheet Load calculation at:
http://harken.com/calculators/MainsheetLoading.aspx
Try it out. V is relative wind speed. Let me know what you get for your mainsheet load, and what you used for wind speed.

Using a simple Lewmar chart for my 31' boat, I get 1,100 pounds. At 4:1 that is still, by your estimate, 5x more than I can pull. So here so far we do not have convergence.

Thanks,

Jim



Ian,
Wake up calls are most appreciated. I'd rather figure out the errors of my ways while sitting in front of a computer than....

First, my question on halyard was misleading. I failed to specify that I want Sta-Set-X (or equiv.) for halyards. My sense is that once set, halyard loads will not change very much, unlike sheets. So my question is: Are halyards subject to shock loads? If so, then I must take that into consideration.

I may be thinking about shock loading incorrectly. In sizing my lines, I am looking for any event that may impact halyard load significantly beyond normal setting tension. If it exists, I want to quantify halyard shock load in pounds added to normal tension.

Also, I have no doubt that you are right about a stretchy mainsheet not getting the best performance.

Thank you for wanting to asses my experience. That is important. I have sailed a 26' S2 7.9 for 12 years in Prince William Sound in Alaska. Sounds good until I add that the boat was 300 miles away from where I lived and worked a day job, so boat outings were limited to occasions where I could get away 4 or 5 days in a row. Oh, and the practical boating season is only about 5 months. So I would guess that all boils down to maybe a year's worth of good hands-on mostly solo sailing. Still, I got out, met some challenges, and lived to tell about it.

After about 4 seasons I replaced the running rigging on the S2. I used 3-strand nylon for the mainsheet as an experiment. Having experienced a few boom-slams, I wanted to try stretchiness to back me up when I was distracted or behind the curve. I was very happy with the results. Not being a racer, I never noticed a performance loss though I did not pay much attention. I spent a lot of time in the Valdez Narrows (about a mile across) sheeted in hard, having too much fun beating my way uphill, tacking, and not getting run over by tankers.

The boat that I am rigging is a Southern Cross 31 with ~240 sqft of mainsail. The textbook for my questions is Brion's "Rigger's Apprentice" from which I got most of the rope information, and all of the formulas and charts that I used to arrive at my initial plan.

I am now seeking from you and all a peer review. I appreciate your feedback.

Rigging needs are halyards and sheets for jib, staysail and mainsail. I have books and internet, and you and Allen are my wise old mentors with pipe and cool hat.

My questions remain:
What is the range of mainsheet diameters that feels comfortable to your hand? (subjective - no engineering required)

What load is your mainsheet designed to carry? Allen questions my 2,000 pound figure so this is a good challenge to work through first. We can deal with line material elsewhere.

For halyards (with Sta-Set-X for example), are shock loads significant as they are with sheets? My definition of shock loads includes any event that might add load above set tension.

Lastly, Ian, what is an AB? (I'm guessing Assistant Bos'n)

Thanks,

Jim