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post #1 of 3 Old 07-19-2007 Thread Starter
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tuning the rigging

This probably sounds really stupid to a lot of you but I've never tuned the rigging on my Niagara 35. Owned her for two years, left the mast on over winter and rigging seemed OK in spring. I asked around the club and got no definitive answer that I needed to tune/adjust etc. And, she sails OK.

Anyone with experience on this? Would love to hear from you.

thanks and regards
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post #2 of 3 Old 07-19-2007
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Signs that you need to do something here would include excessivley slack leeward shrouds while beating, excessive weather helm or markedly different performance on one tack over the other.

Things to look for are if the masthead is centered over the boat, and that the mast stays in column on both tacks. (It may exhibit some intentional fore-and-aft bend, but probably not so much on a Niagara 35)

Use the main Halyard as a "tape measure" and stretch it to a point on the rail abeam of the mast. Then use that same point on the other rail and see if the distance to the deck is the same. If they are the same this means the masthead is centered. If not adjust the cap shrouds to make it so.

Next sight up the sailtrack to see if the mast is straight. If it pulls in the middle one way or the other, the lowers can be adjusted to true things up. Once straight, shroud tension can be set with a Loos gauge according to data for your boat.

Fore and aft location will affect the weather helm - moving the mast/rig forward will reduce, aft will increase. If the boat sails OK now you can probably leave it.

Next go sailing and sight up the sail track and note any bend that you don't like - and adjust to suit. (note - adjust the shrouds when they are unloaded - to leeward- then tack back to check the result.)

On most cruising boats you wouldn't expect the leeward shrouds to slack off significantly until you had a good 15 knots apparent. (others will have different numbers here, I'm sure)

It's a straight forward but somewhat time consuming exercise. In your case it may just need checking.

Last edited by Faster; 07-19-2007 at 10:38 PM.
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post #3 of 3 Old 07-19-2007
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Faster gives a good basic method of cap shroud and lower shroud tensions; but, there is one important tension of the forestay/backstay that you should consider.
If the tension in the forestay (adjusted by tensioning the backstay) is too slack the boat will not point very well, will have problems when attempting to come up to the wind when tacking, and will have the tendancy to heel aggressively while not going forward very well. A Niagara 35 should have approximately no more forestay 'sag off to leeward' than about 6" when beating/pointing in 15 knots and heeled over. A sailmaker will expect a certain amount of forestay sag on a boat and will cut the sail based on this expected forestay sag; if the shape that the sailmaker put into the luff of the sail when making the sail doesnt match the forestay sag ----- the jib/genoa wont perform very well or will be come 'cranky'. Next time in these condition (and with 'moderate' jibsheet tension) simply go forward, lay down on the deck at the bow and simply look up along the forestay and 'estimate' the amount of forestay sag and then adjust the backstay until you get the 'desired' forestay sag. Otherwise (and if this seems too complicated)... the backstay (which reactively tensions the forestay) should be TIGHT.

Rigging tension gauges are very good for such tuning. Many times you can borrow one: Cap shrouds at 12% tension, forward lowers @ 15%, aft lowers at 12%, backstay at about 18-20%. then you go sailing and mae the 'final' adjustments based on your eyeball vs. how the mast is behaving and if or not you're gettiing adverse bending when the rig is heeling in ~15kts.

Hope this helps.
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