Spreaders or lack of

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libellule

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As previously posted, I am doing up a Windy 525 I bought here in France. Have taken on board your replies to my previous question about the need for spreaders and have now sailed her in very light winds with no spreaders and was a little alarmed about the movement at the mast head. The mast is 7.5 metres high and the shrouds are fitted at 3 metres from the base. I have sourced a spreader fitting for my mast, very old, make unknown but basiclly an oval shape 7 x 5 cms. I have sourced spreaders that I can adjust from 350mm to 450mm. My question is..........where is the best height from the base of the mast to fit the spreaders? is there a formula? or is it just a matter of trial and error. The Windy website says they should be 40cms long and at an angle of 120 degrees. The fitting I have sourced allows for the angle to be adjusted. Any help appreciated.
 
Plowing back through old posts, I've found one from Australia (William H)(2003), that states the spreaders should be fitted halfway between the hounds and the deck, (keel in my case). So unless anyone has any better suggestions, thats where they are going when they arrive. (fingers crossed)
 
libellule said:
Plowing back through old posts, I've found one from Australia (William H)(2003), that states the spreaders should be fitted halfway between the hounds and the deck, (keel in my case). So unless anyone has any better suggestions, thats where they are going when they arrive. (fingers crossed)
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I would suggest that halfway between the gooseneck and the masthead is more common and an angle of 5 degrees inboard from vertical on the caps (i will let you do the maths)
 
... but whether the spreaders are swept back or not, they should be angled vertically to bisect the angle between the upper and lower shrouds. That way they will take only compressive forces, not bending as well.

Mike
 
Hello libellule
I think your primary problem is that the cap shrouds are not reaching high enough up the mast. Is it possibole that what you have fitted at 3 metres are really intermediate stays and the caps have been lost. Cap shrouds would go to about 6.5 metres from the bottom. This will help stabilise the unstayed length of mast you presently have.
For a really strong rig add cap shrouds then fit the spreaders at the point where the present stays meet the mast.
It is likely that the chain plates where the stays fit to the hull are mounted aft of abeam the mast by aprox 40 cms. This stops the mast falling forward.
If you fitted the spreaders at 3 metres at the same point as lower stays meet the mast then they should be angled backwards to meet the cap shrouds straight line mast to chain plate. However if you angle the spreader further aft then the spreader will push the middle of the mast forward. This will be resisted by the lower stay pulling aft so making the middle of the mast stable. That would make a robust rig for your dinghy. The spreader base needs to be robust in holding spreader aft. A said spreader is angled slightly upwards .
Of course anything less may be OK dpending on the inherent rigidity of the mast itself. PM me if you want further suggestions olewill
 
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