My 5.7 will kept with the mast stepped all summer. How tight should the shrouds/forestay be? The manual only references "allowing the mast to rotate freely". The wires seemed to be in tension before I raised the sails, (I had my buddy pull on the trap wires to pretension them when I placed the clevis pins in the shroud adjusters), but once I got sailing,(light wind 5-10mph) the lee shroud had enough slack that it would flop around a bit. Is that to loose? If I do them up tighter, should they be slacked off after a days sail, or is it OK to leave them like that til October?
Question two, diamond wires. The manual says to be able to press them against the mast, between 12" & 20" up, & if you don't want to adjust them each day, just leave them in the "medium" position. When putting this theory into practice it became apparent that 12" is a variable target. It depends on how hard you press. I thought they were too loose, & did up the turnbuckles a couple of full turns. I could still press them against the mast at 12", but it took a pretty hard press, so I loosened them off a bit. I don't have one of those fancy tension gauges, what do experienced people do? Push just using a thumb, to the point where your thumb is starting to get a good bend, or to the point where you have to get your arm behind the thumb? Does anyone have any cross references that equate to "X" amount of tension. Could I place a block of wood on a scale, then press the wood against the wire, & with the scale reading "X" pounds, that would equate to "X" amount of wire tension?
I am not experienced enough to really appreciate the gains of very fine tuning, but would like to be able to judge what light/medium/strong tension feels like. I don't want to put unnecessary strain on the rig, or worse have it come down because things were set to loose.
The manual states that diamond wires are the most critical tuning adjustment, so I would like some knowledge here, as it seems to be a valuable depowering option.
Thanks.
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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
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Standing rigging tension on a 5.7
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Posted: Jun 15, 2010 - 02:12 PM
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Posted: Jun 15, 2010 - 02:42 PM
No that's right, when the sail is under load the lee wire will slack off, even on a really tight boat. They should be as tight as you can make them by hand and still get to the same hole on both shrouds. So you set you forstay to the correct rake and then go to each shroud pop the pin and reef down on the shroud while your buddy puts the pin back in. You don't have to hang off of it, it doesn't have to be super tight but you shouldn't be able to get it to the next hole with just arm strength.
I wouldn't over think the diamond wires too much. Thier primary purpose is to keep the mast from bending sideways tightening on the lee to counteract the forces of the main sheet and the shroud. With your raked spreaders it can also induce a certain amount of mast bend aft (more bend =flatter sail and less power). The Nacra 5.2 tuning guide says to make them tight until it just starts to induce prebend allowing the downhaul to work most efficiently to induce the mast bend when you need it.
Here's a link to that tuning guide:
http://www.goosemarine.com.au/_content/documents/general/11%20nacra%20dn%205_2%20tuning%20guide
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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