How to get the best out of a wind vane ?

[justwaiting]

The advice often given out on the forum is for boats to get a wind vane, especially when the discussion is based on solo sailing / distant cruising. What has got me thinking is just how much impact does sail trim have on how well they operate. Like the issue of sails as a wing the way that wind vanes operate is more voodoo that science to me, coming from a power boat background rather than a "sailing background". So how do you get the best out of a wind vane and can any one explain how they interact with sail trim. Thanks guys.

[msponer]

I am not smart enough to distill this well, but here's a rough stab:

- The mainsail tends to push the boat into the wind
- The jib tends to push the boat away from the wind
So figure out which way the boat wants to turn, then one sail needs to push more on the boat or the other needs to push less.

So if the boat wants to turn into the wind, the mainsail should push less and the jib push more. If it wants to turn away from the wind, the mainsail should push more and the jib less.

Make a sail push more by sheeting it in harder, or unreefing it. Make it push less by sheeting it out, or reefing it.

Get the sheets right and that's maybe 80% of sail trim. The rest of the ropes are more detailed control over the shape of the sail (the jib car position, mainsail traveler, boom vang, outhaul, cunningham, halyard tension...) that work on a smaller scale than the sheets. But I feel getting the sheets right will get you 80-90% right.

For other parts... The sails have two modes: wing and bag. Most of the ropes can be thought of adjusting the sail between wing and bag. You want a bag when you go downwind, and a wing when you go upwind, and something in between when you reach or broad reach. All of the little ropes are mostly to adjust the wing or bag shape, and that's how I tend to think of them.

Hope that's helpful.

Oh, and I must agree that I did not really know sail trim until I started using the windvane in tight situations (through the Torres Strait). So it is possible to cross the Pacific and not know sail trim, at least it's possible for me.

[justwaiting]

Originally Posted by msponer

I am not smart enough to distill this well, but here's a rough stab:

- The mainsail tends to push the boat into the wind
- The jib tends to push the boat away from the wind
So figure out which way the boat wants to turn, then one sail needs to push more on the boat or the other needs to push less.

So if the boat wants to turn into the wind, the mainsail should push less and the jib push more. If it wants to turn away from the wind, the mainsail should push more and the jib less.

Make a sail push more by sheeting it in harder, or unreefing it. Make it push less by sheeting it out, or reefing it.

Get the sheets right and that's maybe 80% of sail trim. The rest of the ropes are more detailed control over the shape of the sail (the jib car position, mainsail traveler, boom vang, outhaul, cunningham, halyard tension...) that work on a smaller scale than the sheets. But I feel getting the sheets right will get you 80-90% right.

For other parts... The sails have two modes: wing and bag. Most of the ropes can be thought of adjusting the sail between wing and bag. You want a bag when you go downwind, and a wing when you go upwind, and something in between when you reach or broad reach. All of the little ropes are mostly to adjust the wing or bag shape, and that's how I tend to think of them.

Hope that's helpful.

Oh, and I must agree that I did not really know sail trim until I started using the windvane in tight situations (through the Torres Strait). So it is possible to cross the Pacific and not know sail trim, at least it's possible for me.

Thanks for the response

Background to the question - i have significant sea time mainly under motor, some cruising experience but have only been on one sailboat using a wind vane. That experience (in fact the first hour) was enough to convince me of the value of wind vanes (or at least the aries that was on that boat). That experience was when there was an experienced sailor who understood sail trim (he had been in a number of Sydney Hobart races). My experience was that the greatest value was to be had when sailing up wind, and to exploit that understanding the relationship between sail trim and the wind vane was some thing that i need to develop. I didn't want to drift the thread on sail trim so hence another thread.

So how necessary is it for the sails to be fully balanced before engaging the wind vane? Secondly how does the helming of the boat by the vane affect the way in which you go about trimming the sails?

Thanks

[gjordan]

Almost any vane will steer a boat upwind. Many boats will steer upwind with the helm locked , and the sails trimmed out, without a wind vane. On a reach or run things are different. Dont be afraid to reef earlier than when hand steering, and use a preventor or boom brake on the main. I used an Aries on a 37 foot sloop with a tiller and it steered on all sail points, but usually required a reef on a reach. It sailed dead down wind in light airs with a full main and poled out Genoa, but with more wind I reefed the main first and then changed to a working jib. On my Peterson 44 with an Aries, it was never needed up wind, but on a reach or run it was my best friend. Again reef early for DDW, and rig a preventer and pole out the jib. The Aries handled 25 to 30 knots from astern with a double reefed main and the working jib poled out. Never a problem. It will take a little practice to trim properly, but I consider a wind vane as a necessity on a cruising boat. ___My 2 cents worth.___Grant.

[msponer]

Originally Posted by justwaiting

So how necessary is it for the sails to be fully balanced before engaging the wind vane?

Yes, I think a good way to think about it is that trim deepens the groove the boat is in. Windvanes tend to have less of the rudder throw available to them, on my last boat probably about half of the throw that the autopilot had (which would go all the way to the stops). So they have less ability to get the boat back into it's groove if it gets far out of it.

So how important trim is kind of depends on the boat. Because some boats have much deeper grooves than others, and are much more forgiving of unbalanced sails. The late 70's Perry design I had would fall into very deep equillibriums, and that is one of my favorite things about that boat (and evidence of Perry's skill, IMO). I do not know design, but I feel like a powerful rudder is important, as is a hull shape that doesn't turn the boat as it heels. I have heard, and can see in the shape, that the traditional narrow hulls with large transom hung rudders would also have very deep grooves. I also feel like some racing hulls with large spade rudders and an underwater shape that is balanced as it heels would also tend to have deep grooves, though it may not be obvious to the person at the helm since the rudder has so much power.

So... On this boat the windvane would work very well without balanced sails. Before I knew trim, the windvane would steer reasonably well even with poor trim, though it would let the course wander quite a bit. It depends on the wind and seas, but it was typical for the course to wander 20 or 30 degrees to each side of our intended course with bad trim. We tended to judge the course by the middle of the extremes of the wandering, and set our average course to where we wanted to go.

In some seas this wandering is unavoidable, but in most it's not. Once I learned trim... which is when I was forced to: the Torres Strait is pretty narrow in places, and with a broken autopilot, we were pushing ourselves to get the boat to steer within 5 degree's of our intent. It's funny how pushing yourself to learn something will make you learn it...

Anyways, I've sailed other hulls that do not have deep grooves. I've tried to figure this out, why, so that I could see it in the lines (and avoid it in any potential Boat #2, since I know I really don't like it). And, the best I can figure out, and from conversations with designers, is that some boats have under powered rudders, and the hull has an uneven underwater profile that tends to turn it as it heels. Some, as they heel, tend to throw a lot underwater right at their beam, and they get unbalanced in their drag. Ok, here I really don't know what I am talking about. There's a word for what the cross section of the boat at the waterline, and the thought is that if you look at how that shape changes, that will indicate this effect.

But, the point is, these hulls have shallow grooves that even autopilots have trouble keeping them from freaking out. Add poor sail trim and a windvane that only throws the rudder half or a third as much as an autopilot, and, well, it'll be pretty hard to settle that boat into an equillibrium that it'll stay on for hours on end. The small percent of waves that are randomly slightly bigger or out of sync from the others, or a gust, or whatever, will push it out of it's groove and it'll start on another course, or tack, jibe, or whatever.

So with these touchy designs I think sail trim is much more important. It's no longer about just getting the boat to stop wandering widely, but to get it to stop freaking out every few hours.

Originally Posted by justwaiting

Secondly how does the helming of the boat by the vane affect the way in which you go about trimming the sails?

As to how to trim the sails for the vane, and if it's different to trim the boat for the vane... I think we now trim for the vane the same as we trim for a person or autopilot to steer. Because it is faster and the boat sails a better course. The goal is really to get the helm to feel light, just a touch of weather helm (if any), and for the boat to mostly stay on course if you don't move the helm at all. I guess I define it as a deep groove-- you want the boat to need only small movements of the rudder to stay on course, even as waves and gusts knock it slightly off course.

Under windvane we are more likely to use double headsails or with a reefed main, or no main, on a run or broad reach. I think we also, in general, tend to reef earlier, to keep the boat more balanced. But I do not think we lose any speed because of this, since as we approach needing to reef the weather helm builds and we tend to be dragging the rudder and slowing ourselves down.

So, if there is an algorithm or method that I can somehow communicate through words, it's to get the boat in a groove, set the helm in a pretty neutral position, make sure the boat is staying there for a few seconds, make sure the windvane is centered (the wind paddle is straight up and down, and the pendulum in the water is centered), and then engage the wheel. And then... it's just pushing a small child on a bicycle and letting go-- they just kind of take off an keep going...

You can tell by watching the vane when the trim needs to be fixed. The vane will tend to be steering to one direction more than the other. The pendulum in the water should spend most of it's time centered, with short little corrections to either side. If the boat is getting off course enough that the paddle is going all the way over, or the boat is taking a while to get back on course-- that's the time to retrim and get everything balanced again.

Of course, an advantage of learning good trim is that you tend to sail faster. Because the rudder is not being used as much, so it drags less. How much of a difference, I don't know. I think it's most important in light air, from barely ghosting along all the way up to a little under hull speed.

Hope that helps!

PS-- An interesting thing is that, in many conditions, I feel a vane will steer better than an autopilot. Because it senses the wind and allows the boat to follow the exact wind that the sails are trimmed for. A servo pendulum vane (as opposed to an auxilary rudder type) can additionally feel the stern slew around from quartering seas, and tends to react before the compass heading has even changed. It's pretty cool to watch.

PPS-- This is something that took me years of sailing far to learn, and, from day sailing with other people, I know that many other people don't get it. My crew and I just kind of look at each other, kind of weirdly uncomfortable and annoyed to be on a boat being poorly sailed (it's like watching someone try to Google something and screw it all up, you just want to take the keyboard from them), wondering if we should backseat drive or take the sheet from them and let it out eight inches or whatever... So... I'm hopeful that there's a way to explain it through this medium, but I'm a little skeptical about a written brain download, so I think it's mostly about pushing yourself to learn it.

[justwaiting]

[QUOTE]
You can tell by watching the vane when the trim needs to be fixed. The vane will tend to be steering to one direction more than the other. The pendulum in the water should spend most of it's time centered, with short little corrections to either side. If the boat is getting off course enough that the paddle is going all the way over, or the boat is taking a while to get back on course-- that's the time to retrim and get everything balanced again. [QUOTE]

Just to get thinks clear in my mind. Do you disengage wind vane, trim and re engage, or trim while engaged.

Thanks again

[msponer]

Originally Posted by justwaiting

Just to get thinks clear in my mind. Do you disengage wind vane, trim and re engage, or trim while engaged.

I feel it's easier to adjust the trim while the vane is steering, since you can chill out in the cockpit and tweak things and then sit and watch for a little while to see what the boat settles into, without the distraction of having to steer. For me, at least, it's easier to just watch and feel the motion without steering. I think you just have to be able to translate the way the pendulum moves in the water to what the helm would feel like, but I don't think that's a big leap. You can also see the tension in the steering lines, and on my boat, the blocks would creak if the weather helm built.

But for larger course or sail changes I would have to hand steer to figure out what was going on and then reset the vane. Some points of sail have deeper grooves than others, and so I could, say, go from a reach to a broad reach by adjusting the wind vane and then trimming the sails. Or tack, by moving the vane to where the wind would be on that tack and then handling the jib, but that's easy since the balance is usually symmetrical with the other tack, unless the waves are a lot different.

I was never good enough with the boat to start from zero and set the vane and sails at the same time. Say, go from motoring to raising the sails with the vane all set to go. Maybe because I had the crutch of the autopilot (it was usually working), and would tend to use that. But I generally could not even go straight from autopilot to vane, I usually had to steer for a few moments first to find the center of the helm, where the rudder would spend most of it's time in that groove, maybe defined as the average rudder pressure from weather helm, since that's one of the more important things in setting the vane-- the paddle in the water has to be centered when the rudder is in the most often position, otherwise the vane won't have the full throw of the rudder for course corrections and the wind paddle won't tend to stay centered. These are awkward words that make it sound harder than it is.