Optimum Forestay Angle

[PI Design]

I was curious as to whether anyone has any thoughts on the optimum foretsay angle?

There are quite a few theories/opinions on forestay attachment height, but I don't know any rule of thumb for the angle. Obviously, a greater the angle allows a larger non-overlapping area and reduces stay tension, but this must be balanced against having a low aspect ratio and stepping the mast 'too far' aft. I think a lot of folk chose a mast location (based on a variety of factors) and just extend the forestay to the bow, so don't think too hard about forestay angle but this isn't necessarily the best way.

[Eric Sponberg]

You never want the forestay angle to the mast to be less than 20 degrees. If it is, the headstay does not give enough fore and aft support, and the angle of the head of the sail is too narrow for it to set properly and have good lift distribution. Anything over 20 degrees is OK.

Eric

[Mychael]

And what about the boats that have inner and outer forestays? How does that effect things?

Mychael

[Eric Sponberg]

The same guideline applies, the inner headstay should not be less than 20 degrees to the mast. Generally, the headstay and the inner forestay are parallel, but that is not hard and fast--sometimes the location of structure in the hull under the deck on which to attach the stays plays a part in the stays' design and installation.

Eric