Join Date: Dec 2008
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Originally Posted by Giulietta
2) Longitudinal Adjustment. (Rake)
(NOTE: this has to be done in a day with no wind with the boat perfectly horizontal, shift weight if you have to balance the boat).
Rake will help increase or decrease Weather helm. Aft Rake increases weather helm, improving pointing, forward rake does the opposite.
Normal rake is 1 to 2º degrees aft for cruiser boats and up to 4º deg aft for high performance racers.
a) Install a bucket with water under the boom by the mast.
b) Attach a heavy object to the main sail halyard and dip it the bucket but it should not touch the bottom of the bucket. (The bucket and water are used to dampen the swinging of the halyard.)
c) Measure P, which is the distance from the boom to the top of the mast.
d) Measure the distance from the halyard to the edge of the mast, at the gooseneck.
2) Mast Pre bend
Once the masts are where you want them to be, and before we tension the shrouds, we need to set the masts curvature, or pre-bend.
For this attach the halyard that was in the bucket so it ends at the mast foot.
Now adjust the baby stay and or forestays so that the belly of the mast goes forward. Takes a few tries.
The max bend at rest should not exceed half of the mast diameter.
Still a little confused about mast rake and mast bend and how to put in one without effecting the other. I've seen the diagram showing the difference between the two so that is not what I'm questioning, just implementation of it with a mast head rig, a keel step mast with "spar-tite" around the mast at deck level, cutter rig with furler on the forestay(Pro Furl), bow spirit with bob stay, and heavy dispalcement cruiser. (A Tayana 37) Even with putting somewhere near 25% tension on the backstay, the mast remains vertical using the method of the halyard hanging from the mast head. It seems that in order to get aft mast rake, I would need to adjust the keel step such that the mast sits at an angle fore and aft using shims. If that is the case then there can be no adjustment to the mast rake once the mast is installed on the boat. Is my understanding correct on that point?
The other question is the tension in the forestay with furler. I did look for some way of accessing the wire like you suggested, but I can't locate anything in the Pro Furl. The only thing I can figure is to assume that whatever I put into the backstay gets transmitted to the forestay.
BTW Your videos are great!
DB on the Cheaspeake Bay