Sail angle when broad reaching.

[fredrussell]

When on a broad reach, I’ve always set the sails so they’re perpendicular to the apparent wind. Seems intuitive to me to do so. I’ve recently noticed, however, that some people have the sails further out. I’ve never really given it much thought; what do you lot do?

 

[Minerva]

set them so that all tell tails are flying.

 

[flaming]

If you set your sail so that the flow hits the sails square on, then you just get stalled flow. Sure, you'll get blown along a bit, but you're not using your sails any more elegantly than if you just stood up and spread your coat out.

As far as possible you want to get flow across the sail, from luff to leach. Do that and your sail stops acting like a held out coat, and starts acting like an aerofoil, and you generate a lot more drive.

Of course, the exact shape of the aerorfoil, and all the controls, telltales, tweaks etc, has been the subject of thousands of books. But start by looking to get flow across the sails, and your telltales streaming as much as possible, and you'll be doing better than just being blown along.

 

[oldbloke]

How far the main goes out varies so massively depending on what is in front of it that I wouldn't use that as any kind of a guide

 

[oldbloke]

How far the main goes out varies so massively depending on what is in front of it that I wouldn't use that as any kind of a guide

Sorry, response to OP not flaming

 

[johnalison]

If you set your sail so that the flow hits the sails square on, then you just get stalled flow. Sure, you'll get blown along a bit, but you're not using your sails any more elegantly than if you just stood up and spread your coat out.

As far as possible you want to get flow across the sail, from luff to leach. Do that and your sail stops acting like a held out coat, and starts acting like an aerofoil, and you generate a lot more drive.

Of course, the exact shape of the aerorfoil, and all the controls, telltales, tweaks etc, has been the subject of thousands of books. But start by looking to get flow across the sails, and your telltales streaming as much as possible, and you'll be doing better than just being blown along.

Quite. A school mate with me on the Broads told me to expose the maximum area to the wind. I think he must have been thinking about square-riggers because it’s all about extracting energy from the wind. My current boat has straight spreaders which makes letting the boom well out easy but many newer boats with angled spreaders can’t do this and have to put up with a compromise.

When on a dead run and goosewinging I have found that it sometimes helps to pull the main in a bit to encourage flow towards the jib, which can be useful for short runs when a pole isn’t used.

 

[Chiara’s slave]

If you set your sail so that the flow hits the sails square on, then you just get stalled flow. Sure, you'll get blown along a bit, but you're not using your sails any more elegantly than if you just stood up and spread your coat out.

As far as possible you want to get flow across the sail, from luff to leach. Do that and your sail stops acting like a held out coat, and starts acting like an aerofoil, and you generate a lot more drive.

Of course, the exact shape of the aerorfoil, and all the controls, telltales, tweaks etc, has been the subject of thousands of books. But start by looking to get flow across the sails, and your telltales streaming as much as possible, and you'll be doing better than just being blown along.

Spreading your coat out? Sounds like a flasher You are of course 100% correct. You get, very roughly, 1/3 of your drive from the windward face of the sail and 2/3 from the back, the accelerated low pressure side. Though sitting here on Chiara right now, just the 1/3 sounds comfortably enough, 38knots on the instruments. Luckily we are on our home mooring.

Sailing a fast boat, maybe particularly a multihull, the laminar flow argument is very obvious. Sailing deep downwind, maintaining laminar flow doubles your speed. That is why we tack downwind.

 

[LittleSister]

When on a broad reach . . . what do you lot do?

To oversimplify somewhat, I let the sail out until it just starts shuddering or flapping (or the belly of the sail starts getting backwinded), then haul it in just until that stops.

Has to be done iteratively to both sails (assuming a sloop), as one will affect the other. I am trying to get the genoa to speed the wind smoothly past the front of the main, and especially to avoid it backwinding it. As the genoa has no boom and is sheeted aftwards, I sometime find it hard to get that just right, I will prioritise the main and will tolerate a little backwinding of part of the genoa, and/or wind some sail in on the roller, rather than have it backwind the main.

I am aiming to present the front edge (i.e. mast or forestay) of a nice aerofoil shaped sail to the wind, which is redirecting the wind over it just a few degrees aftwards. I aim to have the sail's tell tales on both sides of it streaming horizontally, but with the ones on the upper/forward side of the sail just lifting.

If I can't get the mainsail out far enough to achieve the above, then I either alter course a little, or have to accept that I'm now in running-before-the-wind mode - less efficient but if it's where I want to go . . .

I would emphasise I am no expert, largely self-taught, and a 'relaxed cruising' type of sailor, rather than one endlessly tweaking to maximise speed. I defer to the greater expertise in sail trim of many on here.

When on a broad reach, I’ve always set the sails so they’re perpendicular to the apparent wind . . .

Having sailed with you, albeit only briefly and a long time ago (so detail lost to my memory), I'm finding it hard to fully believe that.

 

[wallacebob]

The late rally driver Colin McRae said “When in doubt; Flat out!” I was told when sailing, “”When in doubt; Let it out” , most sailors sheet too hard or try to point too high. A more free style gets better speed and comfort. IMHO of course.

 

[flaming]

The late rally driver Colin McRae said “When in doubt; Flat out!” I was told when sailing, “”When in doubt; Let it out” , most sailors sheet too hard or try to point too high. A more free style gets better speed and comfort. IMHO of course.

Especially in the light. If you're slow in the light, find any random control and ease it. Bet you go faster.

 

[winch2]

I grew up "feeling the boat". You slip/pull the sheets until she feels like she's off. Its all terribly simple really.

 

[Chiara’s slave]

Especially in the light. If you're slow in the light, find any random control and ease it. Bet you go faster.

Very much so. And conversely, lots of people don’t sheet in nearly enough when it’s 10-15kn. Boats differ, but to windward, your jib leech is going to be inside the spreaders on a single spreader rig, maybe not quite so far with double spreaders, them being shorter, usually. Boom to the centre line, a nearly straight leech. But try that in the really light, the boat might as well be anchored. Let it all breathe, we say. Halyards, as well as sheets. Kicker, sometimes the weight of the boom is more than enough. A bit on the outhaul but not too much, a massive deep camber isn’t quick in the light stuff either. And this is not just multis or performance boats, we do it on a 115 year old classic too.

 

[fredrussell]

Well, every day is a school day. I’ll put all advice here into practice. Glad I asked!

 

[johnalison]

Especially in the light. If you're slow in the light, find any random control and ease it. Bet you go faster.

I have an oldish book, which I think is called 'Sails', which gives the same advice. It goes on to say that in ultra-light winds it may be better to have flat sails. I don't know the reasoning behind this, but I have never put it to the test.

 

[flaming]

I have an oldish book, which I think is called 'Sails', which gives the same advice. It goes on to say that in ultra-light winds it may be better to have flat sails. I don't know the reasoning behind this, but I have never put it to the test.

In ultra light, yes. This is simply because having a sail with a lot of camber in the light is asking the wind to do a lot to stay attached to the sail. By flattening it you are reducing the potential power, but crucially also reducing a drag a lot.

Though in this context, ultra light is well below anything a cruiser would be attempting to sail in. we're talking 4 knots or less. Even racing we don't sail in that little wind in the UK really, the tide is too strong and we can't make progress until we have about 6-7 knots.

 

[geem]

Especially in the light. If you're slow in the light, find any random control and ease it. Bet you go faster.

When in doubt, let it out!

 

[Daydream believer]

For all the years I have had my Hanse I have never been able to sail with the boom anywhere near the centreline. In fact she goes faster with it set just over the cockpit seats & further. In heavy weather I have the boom there & play the traveller & the fine tune on the mainsheet Letting it out a bit sharppish in the gusts. When it gets too much I finally reef-- if I have been pushing it to beat someone.
I am lucky that whilst the tiller can get loaded, the boat does not round up as some do, when the rudder loses grip.

 

[jwilson]

I see far too many oversheeted sails, but usually in cruisers. Dinghy sailors who grew up racing, very soon find that oversheeting offwind means a string of similar or identical boats passing them. Most eventually get the message.

 

[benjenbav]

Spreading your coat out? Sounds like a flasher You are of course 100% correct. You get, very roughly, 1/3 of your drive from the windward face of the sail and 2/3 from the back, the accelerated low pressure side. Though sitting here on Chiara right now, just the 1/3 sounds comfortably enough, 38knots on the instruments. Luckily we are on our home mooring.

Sailing a fast boat, maybe particularly a multihull, the laminar flow argument is very obvious. Sailing deep downwind, maintaining laminar flow doubles your speed. That is why we tack downwind.

An even more extreme case being the America’s Cup foiling craft where the sails are never to be seen sheeted other than pretty close in.

 

[Chiara’s slave]

In ultra light, yes. This is simply because having a sail with a lot of camber in the light is asking the wind to do a lot to stay attached to the sail. By flattening it you are reducing the potential power, but crucially also reducing a drag a lot.

Though in this context, ultra light is well below anything a cruiser would be attempting to sail in. we're talking 4 knots or less. Even racing we don't sail in that little wind in the UK really, the tide is too strong and we can't make progress until we have about 6-7 knots.

We pray for the wind to die to a zephyr, every single race. Unless it’s on the beam, in the tri, of course. Light wind, with the tide is our dream scenario. Tiptoe through the shallows is our favourite game.