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Old 01-03-2013, 07:02   #1
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single/double spreaders

In reasearching differnt rigs on boats,performance rig is always mentioned when the boat has double spreaders as opposed to " standard mast head " on single spreader rigs. Explain why the double spreader rig would be considered performance.

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Old 01-03-2013, 08:26   #2
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Re: single/double spreaders

Generally speaking it allows the mast itself to be lighter, reducing weight aloft. Single spreader rigs needs sturdier (and therefore heavier) masts.

Some rigs have doubles (or triples, or even quadruples) because of in-mast furling as well. And of course in mast furling adds a lot of weight aloft (the gear, plus the fact that when the sail is reefed or doused it's not down on the boom).

So it could be "performant", or it could not be. Multispreader rigs can pump and wobble a lot more too, and are trickier to tune.

No solid advantage one way or another but you won't see a lot of race boats with single spreaders.

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Old 01-03-2013, 09:19   #3
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Re: single/double spreaders

There are two reasons I can see for using a double spreader rig.
1) Smaller/lighter mast, which means there has to be shorter panel lengths between spreader supports. This may also mean that the mast needs more support for and aft as well as transverse: Double lowers or a baby stay may be required, and running backs or even checkstays if the mast is very light.
2) Narrower sheeting angles to point higher. If you keep the same mast from a single spreader rig but narrow the shroud base at some point you will need to go with a double spreader rig or the shroud angles will get so small that you have compression loading problems. No extra fore-aft rigging will be necessary in this case.

And you could do some of both, make the mast narrower which would lighten it some and reduce the shroud base both of which would point towards a double spreader rig, but leave the mast the same size fore and aft so there would be no need to go with running backs or check-stays.
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Old 01-03-2013, 09:28   #4
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Re: single/double spreaders

Taller/thinner masts need more spreaders. Technically, a mast is a column in compression. If you can keep a column perfectly straight it's amazing how much it can hold even if very small. In a perfect world a mast could be maybe 1/2" in diameter! Unfortunately the real world doesnt work that way. The longer the column, the worse the "slenderness ratio". So more spreaders help to keep it straight.
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Old 01-03-2013, 10:01   #5
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pirate Re: single/double spreaders

Spreads the loads and stress points much more evenly... higher loads to deal with than the average cruise boat..
This also allows the mast to be lighter as the extra stays leave compression as the main factor the mast has to deal with... if set up right... fractional fore prefered..
From my uneducated in race boats viewpoint.. tell me more..

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