Workshop premiere: Mast foot position and batten tension - tips from surf testers, editors and external professionals

The new online surf webinars, which have been running since the end of 2025 and cover a wide range of topics from riding technique and travelling to equipment and technology, are well attended. Reason enough to organise two live workshops with interested participants. The festival on Fehmarn was a good stage and we then presented five key questions to two external experts. An overview of upcoming surf workshops and webinars you will always find in time here.

Marco Lang (Duotone Windsurfing) on mast foot trim, boom height and harness rope length

A lot can be adjusted on the mast base, boom and harness ropes in both senses of the word. Marco Lang gives the key tips for relaxed, controlled windsurfing.

WorkshopParticipants: How to find the right mast foot position?

Marco Lang: When I get a new board and don't know the equipment well yet, I recommend starting in the centre of both the foot runs and the mast foot. The exact position often depends on the conditions. Yesterday on Fehmarn, for example, I noticed that the board felt a bit sticky. In such cases, I push the mast foot back a little to get more lift and air under the nose of the board. However, this also makes the board a little more nervous.
If I need more control and have the feeling that the board could fly away in the wind, I push the mast foot further forwards. Even if the board is not planing in gusts and the sail seems heavy, it often helps to correct the position backwards.

How large should the adjustment steps be?

I recommend taking small steps of about one centimetre at a time. This way you gradually find the ideal position. However, it can be different for professionals. For example, Jordi Vonk, who weighs over 100 kilos, still rides his 118 slalom board with a 7.7 sail in almost 30 knots of wind and then positions the base right at the front because he already has a lot of board lift in such strong winds.

How do you find the right boom height?

Marco Lang: I always recommend making the adjustment on the beach because it's always a bit strenuous on the water. I simulate the mast foot height with my foot. I usually put it under the mast and then I can simulate it roughly. I recommend a height between chest and shoulder as a good starting position. In stronger winds, I move the boom a little further down in the centimetre range. In light winds, I mount the boom a little higher, which gives me more lift and is better for pumping.

Is there a typical error with the trapezoidal lamp settings?

Marco Lang: Yes, the most common mistake is that the trapezoidal ropes are too short.

What rope length should a freerider use? And can the length be adjusted for different winds?

I would recommend a standard length of around 30cm as this is ideal for most people. Many people have photos of themselves surfing these days. It is helpful to use these to check the sail position. It is important that the sail is as upright as possible, because if it is tilted too much it will lose performance. I have often observed that sails are tilted almost 45 degrees into the wind, which significantly impairs performance. This is mainly caused by ropes that are too short.
In the slalom area, riders often use 30 cm long harness ropes with large sails, while with smaller sails (such as 5.2 or 5.8) they even switch to 36 cm. In foiling, lengths of up to 46 cm are even common. It is important to make sure that the harness ropes are not too short, as longer ropes offer more control. Especially in choppy water, you can use your body to better compensate for the chop. I also recommend longer ropes of 30 centimetres or more for beginners, as they are easier and quicker to hook and unhook.

Does height play a role in the choice of trapeze bar length, for example if you are 1.60 metres tall?

In my opinion, height is less important. It's more about ability and personal comfort. However, control is very important. I had a customer here yesterday who was using 28 cm long harness lines with a large freeride sail in around 15 knots of wind. He was frequently falling out of planing because the sail was tilted too far. I advised him to lengthen the trapeze ropes. At first it was a bit tiring for his arms, but in the end he had more control and enjoyed surfing. Even though he had to hold a bit more with his hands, he was super happy in the end.

Gerrit Maaß (Sailloft Hamburg) on batten tension and sail trim in gusty winds

The spectrum of forum recommendations for batten tension ranges from "tighten fully" to "just so that the battens don't fall out". The professional designer takes a more nuanced view. There is no universal recipe for the optimum trim for gusty areas, but there are good tips and helpful suggestions.

Participant question: How should the battens of a sail be tensioned, and how tightly?

Gerrit Maaß: I tension the battens so that the tension increases from top to bottom. The top batten has the lowest tension, while the foot batten has the highest tension, as this is where the profile is strongest. In the top area, I want the sail to be straight and open so that it can open up well in gusts. Too much tension would make the sail bulbous in the top area, which is undesirable. In principle, the batten tension of every sail should increase from top to bottom. In our freeride sails, the two top battens have very little tension, the third batten from the top has medium tension, and the battens in the boom area have the highest tension, as the profile is deepest there.

What is the definition of "moderate" when tensioning the slats? When do you stop turning the slat tensioner further?

You should turn so far that the sail cloth next to the batten pocket is smooth. Slight waves on the inside curve of the batten pocket are normal and disappear when the sail shifts. It is important not to overstretch the battens.

Is the tension tight enough when the creases next to the batten pocket have just disappeared?

Yes, in the centre of the sail, i.e. at the second batten above the boom, this can be achieved with relatively little tension. It should be easy to turn the batten tensioner with two fingers. At the foot batten, where the sail is more bulbous, it takes a little more force, but you can still tension it with two fingers. The resistance is more noticeable here, but you shouldn't overdo it. You also don't want to nail an IKEA shelf to the wall. So you don't have to use force. Once the creases have largely disappeared, you are done with the slat tension. Any more turning will not bring any improvement. And the tension in the top area should really be kept to a minimum, just so that the batten tensioner does not fall out on its own. The less tension in the top, the better.

Reader question: How should I trim my sail for gusty wind conditions, such as on my Berlin lakes?

To trim a sail for gusty winds, I would rig it so that it can withstand the gusts well. I achieve this by increasing the luff tension, which creates a loose leech that helps to cushion the gusts. It's important not to overdo it, otherwise the sail becomes too flat and you get stuck in the wind holes. Personally, I prefer an all-round trim that offers both sufficient profile in the boom area and enough loose leech tension to cope with about 90% of the gusts. This allows you to glide through wind holes and keep the sail stable in the stronger gusts. In particularly strong gusts, however, it may be necessary to open the sail briefly to avoid a spin.

What does an all-round trim look like on a sail like the Cross HR in terms of loose leech and tension on the boom?

The entire trim should be adjusted via the luff. I pull the luff through so far that the batten above the boom is flush with the leading edge of the mast. This means that the tip of the batten should move slightly past the mast until it is practically flush with the leading edge of the mast. When the wind is in the sail, the batten pulls back slightly, leaving enough belly for planing. A clearly loose leech should be visible between the first and second batten from above, as well as a little slack between the second and third.

How much tension should be applied to the clew for this all-round trim when the sail is ashore?

Only minimal tension should be applied to the clew. The point is to tighten the rope so that it is no longer loose and then clamp it - in other words, simply tighten it without pulling too hard. Just enough force in three to four fingers is enough to tighten the rope a little at the back. Tensioning a sail strongly at the clew is of little use in gusty conditions, as too much profile is quickly and unintentionally pulled out of the sail, which makes planing more difficult. For gusts, you need a loose leech and the belly in the boom area to get going. You need to find the best compromise based on the type of sail, model and strength of the gusts and possibly also test different trim options. Ultimately, however, trimming should be done mainly via the luff and not by pulling excessively on the clew.