Genoa Sail trim for broad reach or run

[Scott T-Bird]

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]

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.

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.

 

[jssailem]

Nicely explained @Davidasailor26

 

[Scott T-Bird]

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.

I generally have problems trimming with tell tails as soon as the apparent wind moves aft of a beam reach. It sounds like there isn't anything I can do about the air detaching from the curve at the bottom of the sail, but I can focus more on the upper and middle tell tails. There is no opportunity to move the clew outboard without a whisker pole. I have one in the garage that needs to be fixed. It is one of those twist lock types except that it doesn't lock. Our racing rules state that the pole can be no longer than the J dimension when deployed as a whisker pole so I will probably just bolt it to a fixed length at the J dimension.

 

[BarryL]

Hello,

If you are off the wind and don't have a spinnaker or reaching sail you should be using an outboard lead and a reaching sheet.

Check this out

This allows you have more of the sail pulling and less luffing.

Good luck,
Barry

 

[dlochner]

singlehanding.

Great to hear that you're out sailing on your own after the heart issues and Sue's concerns.

 

[Davidasailor26]

I generally have problems trimming with tell tails as soon as the apparent wind moves aft of a beam reach. It sounds like there isn't anything I can do about the air detaching from the curve at the bottom of the sail, but I can focus more on the upper and middle tell tails. There is no opportunity to move the clew outboard without a whisker pole. I have one in the garage that needs to be fixed. It is one of those twist lock types except that it doesn't lock. Our racing rules state that the pole can be no longer than the J dimension when deployed as a whisker pole so I will probably just bolt it to a fixed length at the J dimension.

For a deep reach you probably don’t want it at or close to the full J dimension. You just want a little extension to get the clew outboard and reduce the draft a bit. For sailing wing on wing you want maximum extension so you can get as much exposed sail area as possible. When you’re going wing on wing it can be possible to get the airflow to go backwards (stern to bow) across the sail, generating some lift. When that happens you’ll see the telltales start to point forward.

Once your trim angles are dialed in It should be possible to keep the jib filled and the telltales at least occasionally streaming out to a pretty deep reach. I’m able to carry the jib and keep it working all the way to the point where I can carry wing on wing.

 

[jssailem]

I was enjoying some deep reaches, almost to the point of a run,

At some point, when you are not satisfied with the performance, you might consider adding another sail to your canvas locker. An Asymmetrical Spinnaker is designed to move your boat in the described conditions and lighter breezes. With no fixed tack point you can swing the sail out to gather greater performance as the wind moves from beam towards the stern.

And there is the amazing picture you produce for those on shore.