setting genoas for downwind

[Birdseye]

Appreciate that many on here witill be more concerned about code zeros, but we dont have on. My rig is masthead and when single handed or light crewed I dont fly the spinnaker. Particularly in decent breeze and not racing I sometimes fly just the 140% genoa.

Now despite many years sailing I am still unsire how to sheet the genoa once the wind is well aft the beam, and as a cumpulsive sail tweaker I would like some advice. Easy when beating to use telltales but aft of the beam? How do you set the genoa for best effect with, say, the apparent wind at 120 degrees?

 

[bobgarrett]

With a whisker pole. But you must still keep it filled.

 

[flaming]

Appreciate that many on here witill be more concerned about code zeros, but we dont have on. My rig is masthead and when single handed or light crewed I dont fly the spinnaker. Particularly in decent breeze and not racing I sometimes fly just the 140% genoa.

Now despite many years sailing I am still unsire how to sheet the genoa once the wind is well aft the beam, and as a cumpulsive sail tweaker I would like some advice. Easy when beating to use telltales but aft of the beam? How do you set the genoa for best effect with, say, the apparent wind at 120 degrees?

Once the wind is well aft of the beam your genoa is not the "right" sail. It's designed to go to windward, so if quite flat with a shallow entry and a straight luff. And as you haven't moved the tack to windward, or forward, it's getting hidden by the main.

Therefore anything you do is a "least worst" approach, rather than good trim.

Assuming that as you're cruising you don't want to be messing about with outboard leads etc, then you are faced with a choice between getting the car forward to work the top of the sail, and leaving the car aft to allow you to open the slot wide at the foot without getting a lot of "return" from the leach where it ends up pointing at the main when the car is forward with the sheet well eased. I tend to favour car aft from where it "should" be and try to keep a smooth flow along the back of the main, at the expense of an open top 1/3 of the sail that isn't doing much. But if the wind is further aft and the telltales are telling you that there isn't a flow from luff to leach, then go car forwards to work the top of the sail. If you can rig an outboard sheet (often through a guy block) and balance the tension in that and the normal sheet such that the clew is held outboard but also held down, then this is best.
And then work out how high you can take it goosewinged and polled out. If you can poll out at 140-150 then this will always be quicker than trying to get it to work behind the main.

 

[Allan]

Once the wind is well aft of the beam your genoa is not the "right" sail. It's designed to go to windward, so if quite flat with a shallow entry and a straight luff. And as you haven't moved the tack to windward, or forward, it's getting hidden by the main.

Therefore anything you do is a "least worst" approach, rather than good trim.

Assuming that as you're cruising you don't want to be messing about with outboard leads etc, then you are faced with a choice between getting the car forward to work the top of the sail, and leaving the car aft to allow you to open the slot wide at the foot without getting a lot of "return" from the leach where it ends up pointing at the main when the car is forward with the sheet well eased. I tend to favour car aft from where it "should" be and try to keep a smooth flow along the back of the main, at the expense of an open top 1/3 of the sail that isn't doing much. But if the wind is further aft and the telltales are telling you that there isn't a flow from luff to leach, then go car forwards to work the top of the sail. If you can rig an outboard sheet (often through a guy block) and balance the tension in that and the normal sheet such that the clew is held outboard but also held down, then this is best.
And then work out how high you can take it goosewinged and polled out. If you can poll out at 140-150 then this will always be quicker than trying to get it to work behind the main.

That's really interesting, we often use what we call cruising sheets, led through a block on the toe rail. I've never used them with the sheet. I may try moving the block forward.
Allan

 

[Birdseye]

Once the wind is well aft of the beam your genoa is not the "right" sail. It's designed to go to windward, so if quite flat with a shallow entry and a straight luff. And as you haven't moved the tack to windward, or forward, it's getting hidden by the main.

Therefore anything you do is a "least worst" approach, rather than good trim.

Assuming that as you're cruising you don't want to be messing about with outboard leads etc, then you are faced with a choice between getting the car forward to work the top of the sail, and leaving the car aft to allow you to open the slot wide at the foot without getting a lot of "return" from the leach where it ends up pointing at the main when the car is forward with the sheet well eased. I tend to favour car aft from where it "should" be and try to keep a smooth flow along the back of the main, at the expense of an open top 1/3 of the sail that isn't doing much. But if the wind is further aft and the telltales are telling you that there isn't a flow from luff to leach, then go car forwards to work the top of the sail. If you can rig an outboard sheet (often through a guy block) and balance the tension in that and the normal sheet such that the clew is held outboard but also held down, then this is best.
And then work out how high you can take it goosewinged and polled out. If you can poll out at 140-150 then this will always be quicker than trying to get it to work behind the main.

Thanks Flaming. Yes I accept that its the "least worst" but short handed and cursed with an ally pole that I reckon has lead ballast inside it, needs must. Since my rig is a classic masthead with a 140 genoa rather than the current big main small jib fashion, sticking to the genoa is a viable option in winds above about 12kn true. Or lets put it this way, in 20kn true even when racing the genoa is as good as the spinnaker for me.

The issue that has been puzzling me and which you have commented on is the use of telltales. I had always thought that going downwind, the genoa was simply a barn door with no flow across it. You are suggesting not.

Bear in mind here that my boat doesnt surf and maxes out something like 8kn.

 

[TLouth7]

... cursed with an ally pole that I reckon has lead ballast inside it, needs must.

If you are put off using the pole because of its weight then I would seriously consider ditching it and swapping to a dedicated whisker pole. Windsurf masts seem to be the gold standard, being cheap and lightweight. Given that this won't be used to fly a spinnaker you could probably do away with all the bits of string and just clip it to the sheet and a ring on the mast. If you already have a track on the mast then retain this as you can use this to control twist/sheeting angle at various angles off the wind (by adjusting the height of the inboard end and so the effective length of the pole).

I had always thought that going downwind, the genoa was simply a barn door with no flow across it.

This is true if the wind is perpendicular to the sail, but in general this situation is a pain (slow and unstable due to vortex shedding). If we are in this situation then we tend to alternate goosewinging and sailing higher. Thus there is always flow over the genoa (in alternating directions), and it is less covered by the main (same rig as you). We gybe the main rather than the poled-out genoa as this is much less of a faff.

Of course when goosewinged with the leach as leading edge the telltales are not terribly helpful, but then we tend to steer to stop the sails collapsing, and trim to maximise projected area.

 

[lw395]

For cruising, if there is plenty of breeze, consider dropping the main?
Otherwise, look at how the main and genoa interact. You might try allowing more twist in the main, to make its shape more compatible with that of the genoa. This will mean bringing the boom in.
There is an area between 'barn door mode' and wanting proper flow across the sails. It might pay to avoid this area and either head up or bear away and pole out.
The key is to have a poling out system which is not some cruising instructor shambles which takes 3 blokes ten minutes to rig or stow.

 

[Birdseye]

I often drop the main if there is sufficient breeze and if the apparent wind is somewhere past the 130degree mark off the bow. The alternative is goosewinging which is OK for a long run where you can pole out the genoa and put a preventer on the main but is no good for just 5 miles or so. The pilot is a good one but I still wouldnt trust it dead down wind not least because there is no wind feed into the computer.

I recognise the comment about the poling system lw395 - when racing mine takes two blokes , one of them large, and five minutes. Trouble is the racing I do is NHC and the cost of a decent carbon pole is .... phew ! So we struggle on with the 90s Kemp equipment.

But racing is a different issue anyway. When cruising, the boat is on autopilot unless we are beating - and thats rare. Absolute ultimate speed isnt the objective because thats too much work and effort. Instead if I can go fast enough not to need the donkey, that will do. So I am sat behind the wheel going downwind and looking at the genoa wondering how best to trim it and whether the telltales should be flying.

My boat, a Starlight 35, very definitely isnt one to benefit from tacking downwind.

 

[TLouth7]

The alternative is goosewinging which is OK for a long run where you can pole out the genoa and put a preventer on the main but is no good for just 5 miles or so.
....
So I am sat behind the wheel going downwind and looking at the genoa wondering how best to trim it and whether the telltales should be flying.

I like the idea that 5 miles doesn't qualify as a long run, for us that's an hour or more. I'd pole it out for a 10 minute stretch of water, and our hardware is at least a decade older than yours. On the other hand I very much enjoy messing around with the sails, and setting the pole is a 1 minute job for one person.

I think the issue with trimming the genoa for anything below a close reach is that the correct sheet lead is considerably outboard of the gunwale. Unless you can hold the clew out there is inherently a compromise (between a forward lead that brings the leach in and backs the main, and an aft lead that results in excessive twist).

With the wind coming onto the luff first the telltales should fly as normal, though to achieve this all the way up the luff you will probably be backwinding the main (see above).

Goosewinged with the wind coming onto the leach the telltales are not going to tell you much, being at the wrong end of the sail.

 

[Allan]

I often drop the main if there is sufficient breeze and if the apparent wind is somewhere past the 130degree mark off the bow. The alternative is goosewinging which is OK for a long run where you can pole out the genoa and put a preventer on the main but is no good for just 5 miles or so. The pilot is a good one but I still wouldnt trust it dead down wind not least because there is no wind feed into the computer.

I recognise the comment about the poling system lw395 - when racing mine takes two blokes , one of them large, and five minutes. Trouble is the racing I do is NHC and the cost of a decent carbon pole is .... phew ! So we struggle on with the 90s Kemp equipment.

But racing is a different issue anyway. When cruising, the boat is on autopilot unless we are beating - and thats rare. Absolute ultimate speed isnt the objective because thats too much work and effort. Instead if I can go fast enough not to need the donkey, that will do. So I am sat behind the wheel going downwind and looking at the genoa wondering how best to trim it and whether the telltales should be flying.

My boat, a Starlight 35, very definitely isnt one to benefit from tacking downwind.

I'm not sure if you know but I'm sailing a Starlight 35 now. Yesterday we did about 25 miles downwind with just the genoa. Since doing some long trips we have started using what I call a fixed pole. I've added a fitting opposite the original a use the uphaul, downhaul and a guy back to a block by the gate. It means that we can roll in some genoa when a squall comes or gybe single handed and leave the pole in place. Setting up is simple as the pole stores on the front of the mast. Not sailing today as the wind is 30kts here!
Allan

 

[Birdseye]

Not sailing today as the wind is 30kts here!
Allan

No problem Allan. In the days before our club got a bad dose of H&S and limited racing to a 30kn max, we took the boat out in a forecast 9 which turned out to be a steady 40 odd gusting over 50. Daft but you know the male mentality - fisrt man to say no is a chicken etc. We were the only boat to make the upwind mark, the Lavernock spit buoy and finally I had mutiny from the crew on the downwind leg so we followed everyone else and retired. The fleet included 41 footers. Nothing broke, nothing was damaged. Main on 3rd reef and a bit of genoa.

Ever since I have had huge confidence in the ability of the Starlight. It will handle weather that the same sized Benny wont look at.

 

[Allan]

Yes, I agree, while we we've not had that much wind, the weather we've seen in many thousands of miles gives us confidence in her. A train ride and a day sightseeing in Stockholm beat sailing in 30 knots! We're off to find another tranquil island tomorrow! As it's midsummer, we're not sure if it's day or night!
Allan

 

[Muddy32]

Although I'm cruising more often, I often have a lead from the end of the boom. Seems to be able to increase the shape of the sail.

 

[zoidberg]

This sort of idea....?

But don't do an Alex Gough on it.....

http://greatcirclesails.blogspot.com/2018/01/man-overboard-in-volvo-ocean-race.html

 

[markhomer]

I often drop the main if there is sufficient breeze and if the apparent wind is somewhere past the 130degree mark off the bow. The alternative is goosewinging which is OK for a long run where you can pole out the genoa and put a preventer on the main but is no good for just 5 miles or so. The pilot is a good one but I still wouldnt trust it dead down wind not least because there is no wind feed into the computer.

I recognise the comment about the poling system lw395 - when racing mine takes two blokes , one of them large, and five minutes. Trouble is the racing I do is NHC and the cost of a decent carbon pole is .... phew ! So we struggle on with the 90s Kemp equipment.

But racing is a different issue anyway. When cruising, the boat is on autopilot unless we are beating - and thats rare. Absolute ultimate speed isnt the objective because thats too much work and effort. Instead if I can go fast enough not to need the donkey, that will do. So I am sat behind the wheel going downwind and looking at the genoa wondering how best to trim it and whether the telltales should be flying.

My boat, a Starlight 35, very definitely isnt one to benefit from tacking downwind.

My buddy is selling his 40.7 soon! Might be a lightly used carbon pole up for grabs soon

 

[Birdseye]

And I might be interested. Let me know if it does come available.