Rigging Rope for OC6

While we're on the subject.

Approximately what length do you cut for an ama lashing, and what length do you cut for a wa'a lashing? I got an estimate of a total of 150 ft for a whole boat, but not the component lashings.

I was also looking into quick straps (with the ratchets). That was easy. Yeah, yeah, I know they're controversial, but I've never had a problem with them.

In looking for the center wa'a straps without the ratchets (Outrigger Connection does not carry those) I came up short. Anyone have a reliable source?
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YankeeHo'okele
"Anyone can steer the ship when the sea is calm" - Syrus Publilius

#2 Tue, 06/09/2009 - 12:12pm

Thanks, Cap'n Ron.

That fits neatly with the 150 ft estimate for a complete boat.
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YankeeHo'okele
"Anyone can steer the ship when the sea is calm" - Syrus Publilius

#4 Wed, 06/10/2009 - 1:42am

A fathom is a unit of length used especially for measuring the depth of water.

There are 2 yards (6 feet) in a fathom.Based on the distance between the fingertips of a man's outstretched arms, its size varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around 5 and 5½ feet.

The name derives from the Old English word fæðm meaning embracing arms or a pair of outstretched arms. In Middle English it was fathme.

The average height of a male sailor does not yet approach six feet. On the other hand, my guess the historical arm and shoulder development of sailors has approached six feet for a century.

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YankeeHo'okele
"Anyone can steer the ship when the sea is calm" - Syrus Publilius

#6 Thu, 06/11/2009 - 1:34pm

Sort of like three fingers of Scotch or your race horse being x hands high.

Now, 69 inches between ama and wa'a? I wouldn't do that without a tapemeasure.
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YankeeHo'okele
"Anyone can steer the ship when the sea is calm" - Syrus Publilius

#8 Fri, 06/12/2009 - 5:18am

I don't know where the use of cotton as rigging rope comes from. It's hardly traditional - the Polynesians didn't have cotton. In fact, olona fibre rope from Hawaii was replacing cotton on commercial ships at the end of the sailing era.

Cotton is the only natural fibre rope that shrinks when wet; all the rest of the natural fibres stretch to some extent. While you may think that this shrinkage is good for removing any slack from your rigging, this shrinkage makes cotton susceptible to shock loading - perfectly good cotton rope can break suddenly with repeated hard shocks. Cotton is also VERY susceptible to rot.

A lot of people use "cotton sash cord" which is a woven cotton outer braid over (usually) a synthetic core. For all intents and purposes, it is a synthetic rope as the cotton braid doesn't carry any of the load. However, it is important to ensure the synthetic core is polyester as nylon has too much stretch and the other synthetics (polyproplylene and polyethylene) suffer from "creep" - they relax and stretch when left under tension. You still have the problem with rot in the cotton outer braid, however.

Polyester rope works fine and lasts a long time. It is the only rigging rope recommended by James Wharram Designs for lashing together their Polynesian double canoe/catamarans and was the rope used to lash together the Hokule`a before it's epic voyage to Tahiti and back. The cheapest polyester rope is over twice as strong as cotton.

#10 Sun, 06/14/2009 - 8:06pm