Modifying sail plans and standing rigging

[tigreg]

I presently own a 48' Stadel ketch; 60 ft mast height. I am considering the purchase of a 60 ft LOD, 70ft LOA (bow sprit) steel ketch. The main mast is 78 ft above the waterline. The main mast and boom have yet to stepped and dressed. Sails have yet to be purchased. However, chain plates, deck cut outs, and keel based mast steps are already completed. Does anyone have thoughts on cutting the main mast to < 65 ft. to make the boat intra coastal friendly. The orginal design does not call for a cutter or stay sail rig. Would the addition of a stay sail be a legimate one for one replacement of lost sail area? Does any one have any comments on potential pitfalls/roadblocks or hurdles?

Thanks and regards,
Greg Gerber

[Eric Sponberg]

Cutting the mast down by 13' is a lot. By compensating for the lost area by making the rig into a cutter necessarily moves the center of area forward and will tend to give the boat more lee helm. If the boat has heavy weather helm, this change may be OK, but if the boat is balanced well now with just the right amount of weather helm, then adding the staysail forward will upset the balance, and the boat will be harder to steer.

The alternative is to lengthen the boom as much as possible, if possible, so that it still clears the mizzen, and also add more roach to the mainsail. Adding more roach actually makes the mainsail more efficient because it will more closely approximate an elliptical shape, which is a more efficient shape.

Eric

[MikeJohns]

tigreg

Is this an existing previously built design or a new one-off? If its an old well sailed design then You can just scale the whole rig down in the vertical dimension, this will keep the centre of effort of the rig in the same relationship to the centre of resistance of the hull, and will let you use all the same chainplates, Mast rake can be changed to finely balance the rig.

Alternatively scale the main down, keep the mizzen and increase bowsprit length. This option will give you more sail area with a lower rig and still let you use the existing steps and plates. Adding mainsail roach area may not be a good option depending on the main mast backstay position.

Do you know any of the yachts ratios? Otherwise her displacement, wetted surface area, Righting moment(30 degrees will do)and the design sail area. Then you might get some more usefull advice.

Cheers