Rigid Mast?

[flyingdutchmen]

Is it possible to have a completly rigid mast (ive noticed there is always slack on the mainstays). However this would be set up in a flattend Y position... no rear mainstay. Is it possible to do this or are the forces involved too great? It would be on a 25-35 race boat.
and lastly on a different note the holdy (gotta love my termonoligy) perpandicular to the mast and attatched to the mainstay things... they are there to spread the load equally accross the mast right? and if so would it be possible to get rid of them on the above mentioned boat using of course stronger mainstays etc...

[tspeer]

I'm not sure what you mean by completely rigid. Any mast will have some deflection under load.

I'm not sure if you are talking about a cantilevered mast without stays, or just eliminating the backstay(s). The moment applied by the sail will be roughly the same regardless of the mast configuration - it's just a matter of how you want to transfer that load to the boat. A cantilever mast carries the load in bending, and requires two vertically separated supports at the base (say, at the deck and at the bottom) to transfer the moment to the hull.

If you want to eliminate the backstays, you have three basic choices: move the shrouds (side stays) aft (most dinghies use this approach); take the side loads in bending but still have a forestay that is tensioned by the loads on the mainsheet (the Aerorig could be considered to be in this class); or use a fully cantilevered cat rig (a Laser dinghy or Freedom yacht are examples). All of these approaches have been used for race boats under 40 ft.

As for the spreaders (the struts extending from mast to side stay), these are used to stiffen the mast against buckling and to induce fore-aft bending (swept spreaders). You can eliminate the spreaders if you have a wide enough base for the shrouds. Many multihulls use shrouds with no spreaders. Then you either make the mast walls stiff enough to carry the compression without buckling, or you add diamond stays with short spreaders to stiffen the mast.

This might help: http://ourworld.compuserve.com/homep...S/designhi.htm

Cheers,