
New to windsurf foiling or trying to tune up like a pro?
Windwise coach and Severne Team Rider, Simon Bornhoft continues his ‘Hang In There’ series, looking at different windsurfing styles and disciplines. For this issue we focus on windsurfing foiling and how to get set up for maximise flying time.
Featuring: Matteo Iachino, Mateus Isaac & Balz Muller
Photos: Windwise / Severne
For this feature you’ll discover:
- How Team Severne pros set their harness lines for Foiling Racing, Slalom and Freestyle.
- How you can set your harness lines & boom height for your Foiling sessions.
Read on to answer all these questions and more….
Hang In There: Windsurf Foiling
“Set them short!” In the early days of foil windsurfing, there was a lot of talk about super short harness lines, low booms, and adopting a very upright over-the-board stance. This was due to using particularly small rigs in lighter winds to try to “get going” early and benefit from the super efficient lift you get from a foil. Also, especially when learning, you’re not massively powered up or leaning heavily back in the harness, like ‘normal’ planing windsurfing. So low booms and short lines were initially encouraged as it was very easy to ‘over pull’ on the boom and have the line drop out when learning to foil. However, with the progress of faster foils, dedicated foil boards, harness line set ups, sailing styles, and stances have started to cross over more between fin and foil.
To help you get a better idea of what’s going on, let’s first hear from some Team Severne pro foilers and then look at some recreational set up guidance.
Race + Slalom + Fast Foiling
When it comes to fast foil blasting, racing and slalom, who better to hear from than the flying force that is Mateus Isaac.
Severne Rider: Mateus Isaac
Foiling Style: Race + Slalom
Foiling Kit: Severne Hydro board / HyperGlide foil race sail / IQ
Harness Line Style & Length: SV Adjustable 28-34inch
SB: So Mateus, how do you set your harness line length for your slalom/race foiling sessions?
“I usually use a 28-34 inch SV adjustable harness line that I can move around and adjust accordingly. For regular fin slalom I like to use shorter lines than most because my style is slightly different, I like to be closer to the rig and kind of on top of the board. But for foiling, I will use a slightly longer line compared to my fin slalom set up. And then, just like fin slalom, I’ll trim my adjustable lines – setting them even longer for stronger winds and shorten then back up again for lighter winds.”
SB: How do you position them on the boom? Are there any on water trimming methods you use or recommend?
“For foiling I like to have slightly more pull on the back-hand than on the front-hand to really feel the drive and power.
SB: How do you set your boom height on the Foil board, is that different from regular Slalom or Freeride set up?
“Boom height is about the same, it’s usually around chin/mouth height when standing on the board.”
Now let’s hear from the rapid Italian and foiling maestro himself, Matteo Iachino.
Severne Rider: Matteo Iachino
Foiling Style: Race + Slalom
Foiling Kit: Starboard / SV HyperGlide
Harness Line Style & Length: SV Adjustable 34-44inch
SB: What length lines do you use for Foil racing?
“I usually use between 34 and 44” lines depending on the wind strength and sail size. The stronger the wind, the longer the line, in general, I use around 40” lines.“
SB: To give everyone an idea of how that relates to your arm length if you put your elbow in the apex of the harness line, where would the boom come to on your hand?
“For foiling, it’s elbow to finger tips or barely touching the boom.”
SB: Do you position them any differently for Fin Slalom and Foil Slalom?
“The SV FoilGlide, HyperGlide, and HGO IQ foil sails have less back hand pressure compared to slalom sails, therefore compared to a regular slalom sail I’ll send them further forward. You don’t want to position the lines so far back, otherwise, you will lose balance.”
SB: What about your boom height?
“For foiling racing you want to sail with the boom really high, with the harness lines long and forward on the boom and you really sit down on them and control the drive of the sail more with the back-hand.”
Slalom Race Summary
Okay, so for the racers, it would appear they are going for longer lines, with Matteo Lachino using extremely long lines, even longer than standard fin set up. This is due to the fact that they are now racing so much more powered up and often heeling the whole board and foil massively over to windward to gain control on the sinew sapping upwind and acute mega downwind sailing angles. In race, slalom, and IQ events, the longer lines are encouraging a more hunched, flexed body positions to help hold the rail steady in full flight. This is the opposite of a more upright stance when recreational foiling on smaller sails and larger foil set ups.
As for positioning, due to the sensitivity of the foil trim and constant rig trimming, racers use a more sensitive harness line set up (slightly further forward) to help notice small twitches in rig position and wind changes. Whereas in fully powered regular fin slalom (and freeride sailing) the boards are more stable at high speeds, so the ethos has always been to massively load up, lock down and set the lines to do all the holding on, with proportionally less pull on the rear arm.

Freestyle Foiling
Now let’s venture into the more playful dimension of Freestyle foiling. So whether you’re experimenting with chucking in some duck gybes, playing with some feasible 360’s or freeing the foil from the water, there’s nobody better than the foil freekster himself, Balz Muller. Yes, this is a man who lives a gyrating ankle defying Top Gun turning existence every time he takes to the water. Let’s see what he has to say about his foiling kit set up.
Severne Rider: Balz Muller
Foiling Style: Freestyle
Kit: Freestyle Foil Board & SV Foil Freeks
Harness Lines Length & Style: 30-32cm lines.
SB: How do you measure your harness line length for your foiling sessions?
“After experimenting with line length from past sessions, in light winds, I use the SV Fixed 32“ for a more efficient upright sail position and in stronger winds, I choose fixed 30“ for more control. “
SB: Do you ever set them differently for different conditions?
“It’s important to try different positions until your feel comfy. My tip is to always make big changes and slowly move back to the middle and settle on the best adjustment. I like the feeling of hanging well down in them and having my arms slightly bent to give me room to react.”
SB: How do you position them on the boom? Are there any on-water trimming methods you use or recommend?
“I have the harness Velcro loops a bit looser on the boom at the beginning of my session so I can easily slide them. In lighter winds, I’ll position them close together (well within a hands width) and actually slightly more ‘backwards’ than comfortable, so constantly more front hand pressure and forward pull on the sail. In stronger winds, I re-fix them back again and set them further apart to counter balance the pull from the sail.”
SB: How do you set your boom height for foiling and how’s that different from your regular freestyle set up?
“Compared to ‘fin’ freestyle, I’ll lower the boom for freestyle foiling to gain more control in my moves. Then, just like a normal fin board, I’ll tune the boom slightly higher if the wind drops to lighten the feel of the board, but it’s very small differences. I like the feeling of hanging well down in my lines and having my arms slightly bent to give me room to react.”

Okay, so you’ve seen the videos and no doubt been beguiled by his brilliance and we’ve now discovered that Mr. Muller has some quirky tweaks you could try. Counter to his slalom teammates he uses longer lines in lighter winds and sets them slightly further back than regular fin freestyle to deliberately create front arm pressure. So we can ascertain that Balz won’t be overpulling and risk the line dropping out. Plus he wants maximum distance and some front arm pressure when setting up for moves that your physio would strongly advise against. But no harm in trying his set up and see what you think.
Harness Line Summary
To bring this all together…
- Freeride Intro To Foiling: Harness lines slightly shorter (1-2 inch)than your fin Freeride.
- Powered Freeride Foiling: Harness lines very similar to fin Freeride.
- Race / Slalom Foiling: Same or even longer than regular fin race set up.
- Freestyle Foiling: Similar to regular windsurfing, unless you’re Balz Muller.
Line Position: If you’re using dedicated foiling sails, the harness lines will be set marginally further forward than the equivalent windsurfing sails.

To help you with recreational foiling set up and using something like the SV Alien and RedWing foil here’s a quick FoilWise summary.
- For learning with inboard straps or on narrower boards have your boom shoulder to chin height when standing on the board.
- For faster blasting, wider boards and more outboard footstraps, set your boom chin-nose height standing on the board, especially if you’re at the level of foiling the board over.
- When learning or using very small sails in under-powered situations set your lines an inch or so shorter than normal windsurfing for your first sessions.
- Lengthen your lines to cope with larger rigs, more powered situations or when learning to heel the board and foil heavily over to windward to help you adopt a more sunken stance.
- Mast base further back to create more lift and great manoeuvrability.
- Mast base further forward to keep the nose down and make the board more directional.
- Choose a wider, deeper foil (1400-2000 Front wing) for learning, ‘Early Foiling’ and getting going on smaller sails.
- Choose a narrower thinner foil (750-1200) for faster speeds and controlling more powered up rigs.
Next time, we’ll look at getting the most out of your Alien & RedWing set up.
If you’re looking to get into windsurf foiling the pathway is now so much easier. For our FoilWise courses, we put sailors on SV Aliens and 2000 or 1400 Red Wing Foils. They are super easy to get flying on, incredibly stable and within a few runs everyone is in full flight. Here are a few shots of first day real life foiling experiences.
Ask Simon
If you have any questions about your harness lines or other aspects of your windsurfing, you can ask Simon @ info@windwise.net. Also worth joining a skill enhancing Windwise experience to get the most out of your time on the water and try some stunning Severne kit under the guidance of your personal coach!
Windwise Winds Of The World Tour 2022-23
Freeride / Freewave / FoilWise
Tenerife + Bonaire + FeelViana + Alacati + Prasonisi + Mauritius + More
More guides
Defi Wind 2026: Severne brought the building
Four days at Gruissan. Tramontana 25-45 knots. 1,400 competitors. Blanca took silver, Antoine finished fourth in Foil Unlimited, and Monster and Fury hit the table publicly for the first time ever at Revolution HQ — voted best stand of the event.
Federico Infantino: Main Break and the Desert
Federico Infantino’s 2025/26 Western Australia season, filtered through the surf-style approach he has been refining: small sail, board-led, let the wave do the work.
Wildwest: Balz Müller Goes XXL at Famara
Balz Müller takes his R4D 4.4 and Psycho 86 into XXL conditions at Famara, Lanzarote. Wildwest is a reminder that nobody pushes the freestyle/wave crossover like Balz.
The Wolf Enters the Big League
Fabian Wolf has strengthened his collaboration with team SEVERNE for 026, stepping up to the international racing team. From national slalom to Olympic iQFOiL to PWA racing; the German finished 2025 as Vice European Champion and 5th at PWA Japan, and he’s targeting the top three in 026.
Lina Erpenstein: Ten Years on Team SEVERNE
Lina Erpenstein joined team SEVERNE in 2016 after growing up on flat water in inland Germany. Ten years, multiple podiums and victories at European, national, and international level, a Chile World Cup win, and a medical career later; she’s still chasing the Women’s World Title.
Pauline Katz: Five Years on the Redback
Pauline Katz has ridden the Redback since ’21. Five seasons across Pozo, Chile, and Maui; all on a sail built for riders her size. Here’s why she’s never switched.
Girls on Tour Goes European
Team SEVERNE rider Pauline Katz expands her Girls on Tour women’s windsurfing camp series to a full European calendar in 2026. Seven events across four locations covering waves, freestyle, and slalom; coached by top female pros including Daida Ruano Moreno and Maaike Huvermann.
Blanca Alabau Signs Eighth Year with SEVERNE
2023 PWA Slalom World Champion and women’s foil speed world record holder Blanca Alabau returns to team SEVERNE for her eighth consecutive season. The partnership that started when she entered Formula Foil competition has produced world titles, speed records, and consistent podiums across both fin and foil disciplines.
SEVERNE Margaret River Wave Classic 2026: Jaeger Stone back on top
Jaeger Stone reclaims Margaret River while 17-year-old Sarah Kenyon wins her first Pro Women’s event. Jake Ghiretti scores the highest wave of the competition. Team SEVERNE dominated every podium; all on the Stone.








