Gaff Spreaders.

[Gavin L]

I am rerigging my 21ft 6ins sloop with a gaff mainsail. Does anyone know of a rule of thumb for gaff spreaders? How far above the throat should they have be, can they be inline with the mast or can they be aft swept,if so , how much? Some idea of ideal shroud angles would be useful as well. I am unable to contact the origional designer.
Regards, Gavin Langmuir.

[John B]

rerigging a bermudan boat to gaff.... why who would do something like that ? ME.

on a 20 ft hoist I have about 3 ft from the throat to the spreaders. It could be 2ft I suppose, but it all gets a bit messy up there with the saddle or jaws and the closing angle that the shrouds make. My spreaders are rigid and in line with the mast. I seriously considered pivoting spreaders after hearing of a Buzzards Bay 25 which wrung it's mast after being sailed for too long with the gaff pressing against the spreaders on a run. He fitted pivoting spreaders but I think it's a seamanship issue. ie ...don't let it happen.
I'm wary of them, don't understand them, so stuck with traditional.

Swept spreaders? something else to prevent you easing the mainsail. I don't subscribe to the idea personally.

spagetti
http://albums.photopoint.com/j/View?u=1257037&a=9296207&p=48868075&Sequence=0&res=high
Well Ok... maybe just a touch of sweep.The aft edge of the tips wouldn't be past the aft side of the mast.




[This message has been edited by John B (edited 07-10-2001).]

[Moray MacPhail]

If the cap shroud angle - i.e. the angle between shrouds and masthead when viewd from aft - is greater than about 9 degrees, I'd be tempted not to bother with spreaders at all, just use one set of shrouds and sweep them aft to obviate the need for backstays.

If you do fit them, their fore and aft angle will depend on the arrangement of the lower shrouds - I assume you are fitting at least one set of lower shrouds ?? Generally the cap shrouds will run more or less in line with the mast, so the spreaders will not be swept, or as per the pic above, a bit aft.
You will need backstays to stop the masthead going forward.

Make the spreaders less wide than the beam of the boat, so they don't catch on walls or boats alongside. I reckon a top cap shroud angle of 15 to 20 degrees is about right. Much more than that, and the lowers take too much load.

If there is one set of lower shrouds, they are swept aft to support the hounds. If two sets they'll go fore and aft, and you surely can't want three sets of lowers on a 21'6" boat.


Hope this helps

[Smacksman]

The beauty of gaff rig is that the mast is shorter and more easily stayed than bermudan. My old Emma [24' on deck] has no spreaders and a pair of shrouds each side. The after shroud chain plate is 6" aft of the mast and the fore chain plate level with the mast [as the mast is deck stepped, having no shroud forward of the mast makes stepping the mast a one man job]. The shrouds attach to a mast band about 2' down from the cap. Running backstays run from the cap to oppose the jib halyard tension. On a gaffer, the peak + jib + stays'l halyards should all be positioned to triangulate and counter the forces.

[Ed Harrow]

Sorry that I can't remember more, but on Consolation the spreaders did pivot, tho their "natural" position was a bit swept back. Each was considerably shorter than 1/2 her beam. There were no backstays, but I'm pretty certain that the shrouds that went over the spreaders were a attached a bit aft of the main mast and the lower shrouds. I believe the spreaders were attached just above the double lowers, which were attached just above where the jaws of the gaff sat.