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Strop Lengths??????


skyman

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Now tiger people....

what is better short or long strops on the front upper & lower stays?

There appears to be more sideways deflection on the longer ones allowing the mast to move sideways and slightly to the rear, what have the knowledgable people to say?

No offence meant but as well as Dave S. answering this post can others please respond, otherwise I am going to end up with my rigging cloning Daves boat, this could be good or it could be bad.

What does Ian M. think as he is building the sails?

cheers david

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Whilst most boats have a relatively long strop, i have tried both short and long and the only difference i have noticed in practice is that when you have a long strop you have to duck when walking between the bows and towards the mast.. Every now and then if you don't duck enough the front lowers knock off your hat!

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Strop length is different between all boats.

It really depends on how you rig/put up your mast. For me, I can attach 6 stays from the mast to the boat before righting the mast then attach the rear-upper stays. For me the strop is short.

Some other people put 3 stays on (being the front-uppers, and one rear-lower), then attach the second rear-lower, then attach the front-lowers and the rear-uppers. If you do it this way, then the strop will need to be within reaching height to attach the pully (or to feed the rope/wire through).

In normal operation, the pully on the strop sits forward of the mast (dead centre).

Some people suggest that if you have a long strop, the angle that the front-lowers make to the strop can cause the pully to be pushed to windward or leewards while taking - ie: the force of the mast/rig changing sides/tensions can cause the pully to move, which can result in the mast being pulled differently from one tack to another, which can result in different performance of the boat.

http://photos.papertigercatamaran.org

Neil

[This message has been edited by h20melon (edited 28 April 2008).]

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No offence taken, but most info I can provide is off my boat. It is mostly fairly standard. But please check around. It makes sense.

In regard to what Neil says about rigging the boat, I rig (as per his second example) by attaching three stays, putting it up, connecting the rest and then the front lowers. But my complete lowers remain attached to the rest of the stays, so I connect them at the bottom, not at the end of the strop. In other words, I don't leave the bottom section of the front lowers attached to the boat when stored, as I don't like them vibrating on the boat while trailering. This being the case, it doesn't matter how short the strop on the front lowers is.

I agree with Tom's statement that a long strop on the front lowers is a pain in the neck (literally). I also think that a shorter strop on the front lowers gives you more mechanical advantage (imagine an extreme case where the strop nearly reached the deck - it would have no advantage).

Have a look at the photos on the NSWPTCA web page and compare the different boats and their relative strop lengths.

Regards,

Dave.

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  • 3 weeks later...

as i figure it there is less sideways deflection of the mast with a shorter strop....more with a longer strop....

also as more tension is applied by either mechanical purchase or rig/ mainsheet tension this will induce more curvature... this can be accelerated by a shorter strop having less deflection or slowed by a longer strop which lets more sideways deflection to occur....

so...?

which is better?

has any one thought about this before having their sails cut???

just some thoughts, or is this what makes the tiger sail more/less efficient?

cheers david

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Rear lowers tension will have a far more significant impact on this than strop length. I suggest a discussion with Ian Marcovitch of Redhead Sails, who has done a lot of experimentation with bend in this area and can speak from a sailmaker's perspective.

Regards,

Dave.

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