Genoa Sail trim for broad reach or run

Scott T-Bird

Scott T-Bird

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Oct 26, 2008
6,244
Catalina 320 Barnegat, NJ
I was having a leisurely sail yesterday evening in about 10 to 12 knots wind (very small whitecaps - not very numerous). I was basically sailing downwind with 135 genoa only - no main sail. I was enjoying some deep reaches, almost to the point of a run, with a handful of jibes thrown just for the activity - singlehanding.

I have never really fully understood how to read the tell tales in this situation. On a broad reach, I suppose the goal would be to see all three sets flowing straight back with both windward and leeward tell tales. But without a whisker pole, I suppose that isn't really possible because I never seem to be able to get the results that I am looking for. I was playing with the genoa fairlead moving it forward and aft and also adjusting the sheeting to try to achieve the best speed. It's hard to discern speed changes while the wind is fluctuating without a lot of patience. But I settled on one adjustment that seemed to be the best.

So, the top set had the leeward tail streaming straight back and the windward tail streaming straight up. The middle set had tails on both windward and leeward streaming straight back. The bottom set had the windward tail streaming straight back and the leeward tail hanging down limp. This seemed to be the best I could do based on the tell tails and the speed.

I am supposing that the top of the sail was twisted off and the bottom of the sail was stalled. Sheeting in while moving the fairlead forward to reduce twist at the top did not seem to improve anything and only seemed make all tails go haywire. Any thoughts?
 
Davidasailor26

Davidasailor26

.
May 17, 2004
5,570
Beneteau Oceanis 37 Havre de Grace
Scott T-Bird said:
So, the top set had the leeward tail streaming straight back and the windward tail streaming straight up. The middle set had tails on both windward and leeward streaming straight back. The bottom set had the windward tail streaming straight back and the leeward tail hanging down limp. This seemed to be the best I could do based on the tell tails and the speed.
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Yes, it does sound like you had too much twist. As you ease the sheet to get to a deeper reach the clew moves forward, which means the sheet isn’t pulling down enough to keep the leech closed. Pushing the car forward can compensate for that to reduce twist. As the car goes forward you may need to ease the sheet to compensate for the line needing to take a longer path to the sail. The other problem you might be having is that on a deep reach it’s also hard to keep the air flowing along the very curved sail without separating. When you pushed the car forward you may have pinched the clew further inboard, making the curve even sharper and separating all of the flow.

Do you have any way of getting the sheet and clew further outboard? Our chainplates are very close to the toe rail, nearly a foot outboard of our jib tracks. I attached a block to the chainplate, so on longer reaches we can run a temporary sheet through there and improve the angle a bit. That helps keep the curve from being too sharp, so the flow can stay connected and the maximum draft can stay forward.

Eventually as you go further downwind the air can’t make the turn to stay connected to the larger curve of the sail. At that point the sail just generates drag instead of lift, the telltales fall down, and you’re on a run instead of a reach.
 
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