Upper Shroud Extenders?

[Bob Pingel]

I recently worked on two boats with 15" "extenders" in the uppers. On one boat the extenders are essentially long toggles, on the other the sections of wire are held together with aircraft eyes and forks. Both boats have deck stepped masts with pivoting steps.

I suspect the extenders have something to with stepping the mast, but I can't quite see it.

Anyone have any ideas?

Thanks,

Bob

[Brion Toss]

Hi Bob,
If the lengths are right, the upper terminals of the extenders will be just at the height of the mast's pivot point. So, with the addition of fore-and-aft bridles, made up tight, the upper shroud, without needing tending, won't go slack as the mast is lowered. Thus it can provide lateral support for the mast. The only other way to accomplish this is to have the mast's pivot point at the same height as the chainplate pins.
Fair leads,
Brion

[Bob Pingel]

I get the concept, but don't see it...

The upper ends of the extenders are a foot or so above deck -- at the level of the step. When lowering the mast what do they attach to?

You mention bridles -- are the bridles on the mast or on the ends of the uppers (at the top end of the extender).

Bob

P.S. Boy, a drawing would be great here...

[Matthew Sebring]

I may just be adding to the confusion here.... Picture a mast sitting on a level plane with it's chainplates such that the pins are in line with the mast step bolt that the mast pivots on. Obviously the whole thing would allow the mast to fold for or aft as if it were a hinge. However, if you move the chainplate pin away from this pivot point the geometery changes so that as the mast is lowering it is either applying tension to the shrouds or compression (ie, the shrouds go slack). Unless everything is kept in line you cannot have the upper shrouds keeping the mast in column as it pivots for or aft. The purpose of the extensions is to pring this pivot point up in line with the pivot of the mast. The bridles are attached to the extensions (and led to the toe-rail or padeyes or the like) to keep their fore and aft positions constant. This setup allows the mast to be stepped and unstepped as if all the pivot points are in plane.