Sail tuning is one of the skills that gets overlooked during the learning process of windsurfing. Most people can kind of rig the sail correctly but are either unsure, or just plain don’t know how to tune a windsurf sail. A badly tuned windsurf sail can make the experience of windsurfing unpleasant. There are only a few parameters you really have to look out for, depending on the sail. This guide should help for most windsurfing sail types although it will vary (or be missing aspects) for sails that have cambers for example.
When I rig my sails there are basically three things I look out for.
How to Tune a Windsurf Sail Correctly
Before I start, a quick disclaimer. Each sail type and brand will have different properties and their performance will vary greatly from one sail to another. This guide should be used to start you off but ultimately it is up to each sailor to test out variations to this starting point to see what works best for them. You can also check out the manufacturers websites to see what they recommend for their sails.
Sail Outhaul
With the sail on the ground I push down on the sail with both hands. The sail foil should be just touching the boom on the other side. If it touches too easily I tense the outhaul more, if it doesn’t reach the boom I release some outhaul.
This also depends on the wind. If the wind is light you can release the outhaul a little to make the sail curve more round. If the wind is stronger or you feel overpowered you can tense the outhaul more to make the curve flatter so the sail doesn’t pull as much.
Too much outhaul
If we pull too much on the outhaul, the sail will be very flat, which means that it will lose the profile. This means that all the advantages of having a wing shape are lost and all you are left with is a wall for a sail.
For vey strong winds this can help take some power out of the sail so that you can get back to the beach but the performance is greatly compromised. It is also not very good for the life of the sail.
Not enough outhaul
If we do not pull enough outhaul the sail will have too much of a curve. This is bad for two reasons:
Firstly, we will not be able to go upwind as much as the angle of attach when on a close haul is steeper.
Secondly, the battens will not be able to change the side of the mast easily. If they don’t change onto the lee side we have a bad sail profile which is not efficient. And if they have to be passed on to the other side with a lot of force, the end of the batten sleeve will wear out fast and there will come a moment when you have the batten poking out next to the mast.
Sail Downhaul
The leech (the outer edge of the sail between the mast top and the end of the boom) should be loose up to about the 3rd batten starting from the top (for wave and ferried sails) and until nearly the batten just above the boom (for slalom sails).
The reason for the loose leech is that the wind is faster the higher up you go. Therefore the angle of attack of the sail has to adjust to the different apparent wind at that height. That is why slalom sails (which are usually bigger and higher) need more loose leech.
Another benefit of the loose leech is that the sail is less rigid which means that in gusty winds it is less aggressive to catapult you. You control the loose leech with the downhaul.
Too much downhaul
If we pull the downhaul more than is necessary, we will have a long loose leech. This greatly reduces the effective sail area which reduces the power that we can get out of the sail. This is OK if we want to use a sail that is too big but obviously, going down a sail size might be a better solution.
However, sometimes we only have one sail, or our next smaller sail is too small and the only solution is to play with the tuning.
Not enough downhaul
When we do not tense the downhaul enough we leave the mast too straight. One result is the wear effect that we have with too little outhaul mentioned before.
The other reason for making sure we put enough downhaul on the sail is that, with a flat sail the pressure point is unstable. With every movement of the sail it seems to wander around. This is really uncomfortable for relaxing in the harness.
Aside from that, the lack of loose leech also means that the top of the sail contributes to the active sail surface, bringing the sails pressure point higher. This results in the sail being more prone to catapult you.
Mast curvature
The first batten above the boom should be at about 1/3 or 1/2 of the mast width. The reason for this is that I have found that it works best for air flow performance and also allows the battens to change sides when going into the other direction. This is controlled with the downhaul and the outhaul.
One last tip
In terms of altering the aspects of the sail, keep in mind that you want to get the downhaul set correctly before you mess around with the outhaul as it has the greatest impact.
Windsurf sail tuning
By now I hope you will have realised the importance of having the sail tuneed correctly. With these guidelines you should be off to a good start. I recommend you test different settings and see how the performance of the sail is affected.
If you have any questions regarding tuning the sail, let me know in the comments.
Many thanks for this article. I have been looking for a long time this kind of summary of trimming. Now, I think, I understand the main aspects of it:) I will try your guide as soon as the wind reaches the shore here in Croatia/Hungary. I’m glad to find your page/blog. +1 follower:)
Thank you Zoli for the feedback! That was my intention. I have seen different pieces of advice but never a list of things to look out for. Obviously in the end it comes down to prefference and trying out which setting works best for you. As a starting point I think it should help. All the best! I hope you get to try it out soon 🙂
hi Anne there is a lot to talk about i am just getting in to planing a smaller board i am a heaver sailor up to the 20 stone and have a 146 leater board, i feel that as i begin to get the right wind power to plan the board seems to try and jump out of the water and slows and trays too jump gen and slows and try to jump gen this harpoons very quickly within a second or two and i miss the gust healp
Hey Paul! I think the predictive text on your phone has made your comment a little hard to understand. If I understood correctly you are having trouble that as soon as you start planing your board jumps o of the water, causing you to lose control which means you slow down and that this happens once or twice and then you stop.
What might be happening is that your board has a fin that is too long. This usually causes the board to lift out of the water, although this is less likely with heavier sailors. Aside from using a shorter fin you can also try putting the mast foot further forward to keep the nose of the board steadier.
I hope I understood the question correctly and that my advice has been useful. Let me know how you get along 😉
Arne
Thank you so much! I’ve been looking at sail rigging videos all day trying to figure out what I was doing ‘wrong’. Because no matter how i tried the main batten above the boom wouldn’t sit by the side of the mast and kept being on the third or half of the mast width (as apparently it should).
Great description and a great refresher for me. Over time and pauses it windsurfing, I have forgotten a few of these points and it shows. I remember helping out a few friends with rigging and the difference it made to their sailing. If you are fighting your rig you can’t focus on your sailing which can be a total fun destroy.
Cheers.
Same here. Best summary I have read soo far! Thank you.
Your drawing of downhaul is spot-on, good job, and the mast bend thing that shows the batten half on is also very good. The outhaul drawing is flawed, I think, since boom shapes can vary quite a bit, as can sail shapes. The difference between a Sailworks Hucker and a Simmer wave sail is quite dramatic, and I think should have been mentioned more.
At the end you say downhaul should be set first. Then put downhaul section of the guide before the outhaul section. The section called “mast curvature” has nothing to do with mast curvature. I also disagree with content in this section, the amount of mast overlap is extremely variable according to the design of the sail.
Another useful point is that when the downhaul is increased, the boom length of the sail increases, so that outhaul is usually increased (to maintain the same degree of tension or profile).
Thanks a lot for the effort of writing this guide, helps a lot!!!
Im glad it it useful to you 🙂 Thanks for the feedback!
Hi Arne,
After 20 years of inactivity I start windsurfing again and it is quite hard for me now finding again the feeling and my good windsurfing of 20 years ago, everything is complicated, I am 87 kg and I use a board of 97 kg. Last time I went out 16 knots I felt a lot of power in the sail but it wasn’t translated in the forward movement of the board. Maybe I was closing to much (bolina) the wind. Or I was not effective with the harness. It is possible that another cause was the mast foot was too forward for that little wind.
All my mates were planing very fastly (it is tru they have 15 kg less than me) but I could only plan if I went (at lasco) away from the wind.
Sorry my english windsurfing vocabular is not so good.
Thanks for the useful tips
Hey Gianluca! That’s awesome that you are getting into windsurfing again! As for your problem: from what I understand you might have had one of two problems. The first is that you used a modern board which is mich shorter than the boards from 20 years ago. This makes the boards more likely to go upwind (bolina) and you have to force it downwind by leaning the mast forward and to the wind and sheeting in.
The second is that you either had a too small sail (how big was the sail? Were your friends using the same size?) or you were not transmitting the power of the sail into the board correctly. Check out the post on planing (type in “how to plane” in the search box in the tip right of the page). To start planing you will have to go downwind a little first and then turn it to continue planing upwind.
Hope this advice helps. All the best and keep it up! 🙂
Hello Arne!
Very helpful article, I ‘m looking forward to fine tuning my sail before my next session.
Could you provide some info on the principles of tightening (and untightening!) the battens please? I know the idea is that if you have “ripples” on the sail you are supposed to tighten the batten (or battens?) but this is very vague. I am sure I overtightened my sail’s battens last time but the ripples were there (just moving on different parts of the sail).
OMG – for years i have just been reefing the downhaul and outhaul as tight as possible… and wondering why i can’t get enough power out of an 8.5m sail to plane properly. i absolutely can’t wait to go and try out all this stuff at the lake this weekend. thanks
Hey Moe! Glad you found it useful 🙂 Good luck dude. Although remember that with bigger sails you will need a little bit more downhaul than is described here 😉
Thanks for the guide,I am currently trying some windsurf sails on my land yacht so as a non boarder it gives the starting point I needed
Great tips! Very Clear!
I wonder, though..I just bought a HSM Superfreak UL( 8.0)). Haven’t tried it yet.Its design, though, is slightly different from conventional sails : the sail is designed for a relatively tight leech because the central battens are a few inches away from the mast and the sail can therefore rotate with less d/haul than usual. These characteristics seem to defy the golden rules applicable for regular sails. I usually sail in light winds ( 15-18 knts max, sometimes 12 knts. Perhaps a tighter leech in these conditions will be beneficial as less wind is spilled from the top..
Any comments on how I should expect the sauil to react as compared to more conventional sails?
Thanks
Franco
In the pictures, it looks like you are demonstrating with a Naish Moto sail – is that right. I have a Naish Moto and I’m ready to give up on it, but the problem is probably me. I’m finding that when I I give it enough downhaul for the battens to line-up halfway on the mast, that I end up with a loos leech. How can i fix that?
Hi Arne,
Thanks for the tips on setting up the sail, I searched for it for a long time and found it.
The diagrams are really fantastic, I am actually very impressed by how well they articulate the point.
Back on a windsurfer after 40years of surfing and paddlesurfing, I think I’ve forgotten more than I knew. I talked to a couple of windsurfers today at Leucate about tuning but this article has really helped. I’ll try it tomorrow! Thanks you’ve cleared some of the fog.
If only this was in the beginners books, and included in my couple of lessons – It makes perfect sense to get the aerofoil shape of teh sail correct…. so, basically I’ve had the outhaul far too tight and had the sail as tight as a drum. I’m a complete beginner so the learning curve is steep at the moment and every bit of good advice welcome.
I grew up windsufing on Marthas Vineyard but have not been on a board in 30 years. Recently picked up some used gear. Have a AHD ~105L board. I weight approx. 160 lbs. First time out in 20 to 25 kts…used a 4.5 sail. Second time 18 to 22 used a 5.4. Got a little better the second time. Main issue I seem to have is that the board wants to point up. I’ll get the board on a solid plane, hook into the harness lines, and as soon as I try to get into the straps, she wants to point into the wind…I lose power and have to start again. Wind was very gusty do did not help. I tried resetting the harness lines further back which seemed to help a little. Tried playing with the position of the mast base. Wondered if you had any thoughts? Also what height do you suggest setting the boom? Thanks for any suggestions.
all good but where are the comments on cambered slalom sails?
I recently bought an 5.3Ezzy Panther 2013 in great condition.
I weigh about 80 KG and the board is a 85L
I went out today in about 20 kt and found that the sail was hard to controle.
Either all or nothing and difficult to sail up wind.
I have looked at the videos by David Ezzy and still feel that I have still missed something.
Does it sound like an outhaul issue – Would the profile drawing above be right for the sail I have?
Hi Arne! I just bought a 5.5 and I tried it out yesterday here in Sweden. It was for some reason unsailable… It was really hard doing waterstarts, and when i did come up.. the sail would immediately force the board upwind. I wrestled with it and tried to really force it downwind, played with the position of the mastfoot, played with the outhaul, there were some changes but the result was always the same… I wrestled for like 3 hours 😦 After having read your article here (very good btw), im guessing maybe I didn’t have enough downhaul? I usually use a 7.5 for my AHD 130L, I’ve never even come close to that problem 😦
Hi,
Thanks for a great tuning article… playing with settings on my sails I see how important it is to get both down and outhaul just right… just a few cm can make a world of difference!
Just curious, in the ‘not enough downhaul’ section you mention a flatter sail being unstable. Doesn’t putting too much downhaul on pull the battens away from the mast and flatten the sail? I thought too little has the effect of bagging out the sail when it fills with wind making it draggy, also with a wandering pressure point?
Advice gratefully received,
Thanks