Reefing with a sliding gooseneck

[Jim Fulton]

Originally Posted by Brion Toss

• Someone else mentioned tightening the main halyard as an adjunct to the downhaul. I can earnestly unrecommend this practice, as it has the unfortunate consequence of tightening the leach as well as the luff, and this is the last thing you want.

I would like more of an explanation of the distribution of forces here. As I mentioned in the earlier post, I use the flexibility offered by the sliding gooseneck to raise and lower the center of effort by raising and lowering the whole sail. When the sail is raised to the top of the mast and the gooseneck is at the top of its track, I use the downhaul to tension the luff. When the gooseneck is at the bottom of its track, I use the halyard to tension the luff. (I didn't mention thatI have boom-end sheeting, which may or may not be important.)

In the one instance, the head is fixed and the gooseneck is moved; in the other, the gooseneck is fixed and the head moves. I don't see why the effect on the sail would be different. What am I missing?

Jim Fulton

[Brion Toss]

Originally Posted by Jim Fulton

I would like more of an explanation of the distribution of forces here. As I mentioned in the earlier post, I use the flexibility offered by the sliding gooseneck to raise and lower the center of effort by raising and lowering the whole sail. When the sail is raised to the top of the mast and the gooseneck is at the top of its track, I use the downhaul to tension the luff. When the gooseneck is at the bottom of its track, I use the halyard to tension the luff. (I didn't mention thatI have boom-end sheeting, which may or may not be important.)

In the one instance, the head is fixed and the gooseneck is moved; in the other, the gooseneck is fixed and the head moves. I don't see why the effect on the sail would be different. What am I missing?

Jim Fulton

Hi,
Good question, and I think one at the heart of this discussion. When you tension the luff with the halyard, you just about unavoidably also tension the leach. How much of the halyard's effect goes to either side depends on point of sail, sheet, and vang, but you'd have to impose some very strange evolutions, like topping up the boom, to keep the leach from being affected. But when you tension the luff with a downhaul or a Cunningham, the luff is the only thing that is affected.
In addition, tensioning the halyard has a diproportionate effect on the upper part of the sail, which is relatively small; tensioning from the tack flattens the belly of the sail.
The consequences for sail shape are significant, but I don't question that tensioning the halyard works for you; in many or most circumstances there will be a net gain in performance, with a flatter sail more than compensating for some leach curl. But it ain't optimal.
Fair leads,
Brion Toss