Rig Trim Intro

Windsurfing rigs have by nature an elastic, living character… the aerodynamic form your rig presents to the wind depends primarily on three elements: -sail design (the mast and seam curves cut into the sail) -mast stiffness & flex character -the trim you set into your rig (downhaul & outhaul tension as well mast-foot position and boom-height among other trim settings). Trim sensitivity = Performance & wind range expansion Rig trim is critical to rig performance. Loftsails are exceptionally trim responsive. Trim begins with noting the boom length, mast length and the recommended mast for your sail. The rig reacts directly to two primary trim variables: downhaul and outhaul tensions.


All sails respond favorably to increased downhaul tension for high wind sailing. For strong winds it pays to be radical… increased downhaul tension will produce easier handling and greater speed in strong winds. When overpowered- tension the downhaul! High downhaul tension will open the sail’s leech (rear edge) releasing sail power. High downhaul tension will also flatten the sail body making the rig significantly easier to handle in strong wind and increase your speed and fun! Be aggressive with downhaul tension as the wind rises… Loftsails are built to accept & respond to high downhaul tension. Increased downhaul tension will soften the leech from the head all the way down to the boom- correct “knife-like” trim should your rig feel too powerful in strong winds. Should the wind drop or should your you find your sail size small for the wind strength, less downhaul tension will firm the leech and make the sail body fuller…. such reduced or “soft” trim generates greater low-end power. When winds are sufficient for easy planning it is the right moment to experiment with increased downhaul tension. The adjustment range between ideal low wind trim and ideal high wind trim for a given sail size may be as much as 5cm. Note that the tension applied to the downhaul directly influences tensions at the boom; high downhaul will “soften” the outhaul, conversely low downhaul tension will increase tension at the clew.


The outhaul has direct impact on rig performance.    Reduced outhaul makes the sail deeper in profile generating greater power for light winds. Extreme low wind trim will increase light wind power and also make the rig feel stiff and more back hand oriented, especially should the wind rise. Greater outhaultension flattens the sail profile making the sail much easier to handle and faster in medium and strong winds. Flatter outhaul trim allows the sail to pass more easily through the wind. For a given sail size the range between ideal strong and light wind trim may be up to 6cm. An overly tight outhaul (relative to wind strength) may make the rig feel “nervous” or “twitchy”. An overly released outhaul (relative to wind strength) may make the rig feel difficult to handle and overly backhand oriented. A simple trim reference (cam-free sails) is the position of the forward end of the batten just above the boom.    If this forward batten end passes near the mast without touching the mast, the sail is set for medium winds. If this batten end makes mast contact during rotation the outhaul is set for light- to-medium winds. If this batten end passes well to the rear of the mast, the sail is set well for strong winds. Note that downhaul tension directly influences this trim reference- more downhaul = more distance between the batten end and the mast.

Optimizing Rig Trim

goes beyond outhaul and downhaul sail adjustments. Boom height, the mastfoot position, harness lines and mast type all impact your windsurfing performance.

  • Boom height has a direct performance impact.    Low boom height will make initiation of planing difficult.    An overly high boom promotes early tail walking and makes maneuvers difficult; a good position to begin is chest/shoulder level. In very light winds the boom is best raised to assist in the initiation of planing.    A higher boom places more of the windsurfer’s weight onto the rig and less on the board, consequently the board & fin have greater capacity to lift and plane.If the wind is strong for your sail size, lowering the boom will give greater control. With a lower boom position the riders weight becomes more board oriented; increasing board control in challenging conditions. Generally, wide boards are better suited to higher boom heights- as the windsurfer moves outboard the wider stance drops the boom.
  • Harness lines are your power transfer: their position and length will affect rig performance. The harness lines bear the diving power from the rig allowing the windsurfer to be free!    Finding the right harness line position is a question of balance…Windsurfers who are starting with the harness usually like to place the lines forward- reducing the likelihood of being catapulted.    Lines too far forward will limit speed as the windsurfers position is forced, resulting in more board contact with the water.To place harness lines correctly, go with the flow… if harness lines are too far forward the back arm becomes fatigued. If the lines are too far back the forward arm becomes fatigued. Try sailing with no hands!    When the lines are placed correctly you will be able to sail for long moments with no hands! If you reach for the boom first with your backhand the lines should be moved back. If you reach for the boom first with the front hand the lines should be moved forward. Lines placed further apart may produce a feeling of greater stability. Wide lines (30cm+) will harness sail power comfortably and are generally better suited to beginning and intermediate windsurfers.Narrow harness lines (12cm and less) transfer power to the sailor more directly, more critically. As the harness lines are placed closer together on the boom they make rig trim more direct relative to the sail power center. Racers tend to set narrow harness line placement, often no space between the lines!
  • Harness line length also influences performance.    For average size windsurfers 24 to 26 cm from the line center to the boom is an average harness line length. Short lines limit speed potential… body weight is the power generator.    Body weight too close to the rig and maximum power is unavailable.    Overly short lines (less than 23cm max from boom) limits the reaction time as the windsurfer encounters changing wind and sea conditions. Overly long lines (more than 30 cm) may cause arm fatigue and rather wet windsurfing as the sailor may make contact with the water. Correct harness line position is affected by downhaul and outhaul tension; strong wind trim will shift the harness line positions forward; light wind trim will bring the harness lines further back, the difference being in the range of 2-4 cm. Longer lines (28-30cm +) are associated with slalom/speed windsurfing, while shorter lines (24-26cm -) are the norm for freestyle and wave sailing. Adjustable lines are recommended for competitive speed/slalom disciplines as they allow fine trim tuning while on the water.
  • Harnesses A loose fitting harness affects negatively harness function; power transfer is less effective and is detrimental to your windsurfing performance. Keep your harness tight! Waist-type harnesses are generally used for wave and freestyle windsurfing; they place the hook higher on the body- suitable for maneuver-ease. Racing/slalom/speed harnesses are normally lower on the body, bringing the hook down which may more easily close the rig down onto the board; augmenting speed potential. Lower hooks may also allow the fin a greater capacity to lift witch also augments speed potential.
  • Batten tension is simple! Tension the battens until the sail becomes visibly taught.    Many windsurfers overlook batten tension.    Full batten tension makes the rig more stable as well as removing wrinkles.    Severe over tensioning battens may cause asymmetric profiles and affect batten rotation.    Cammed battens may need special care as over tensioning cammed battens may negatively affect cam rotation.
  • Masts influence rig performance. It is best to use the recommended mast for your sail.If a softer mast is used the rig becomes more flexible; rig handling will normally become easier in high winds and the rig will be easier to close down onto the board (“closing the gap”).    Softer masts will normally make the rig faster downwind. A stiffer mast will have the opposite effect; the rig will become more difficult to close down onto the board in the upper wind range. Stiffer masts tend to go upwind more efficiently compared to soft masts.

Rigging advice

  • -When rigging all sail types, it is very important that as the mast is placed into the mast pocket, the sail head arrives all the way to the mast top before pulling the sail all the way down onto the mast. A fold will occur at the boomhole, which relieves pressure between the mast pocket and the mast top- avoiding damage to the mast pocket. -It is also very important that the mast parts do not slide apart during the rigging process. If your mast has a loose fit, check the joint before downhauling by feeling the middle of the mast with your hand- if you can feel a gap between the mast parts- STOP!… and re-fit your mast! Taping your mast together around the middle seam will ensure your mast stays together, blocks sand entry & allows your mast to come easily apart. -For cammed sails make sure the mast goes in ontop of all battens before applying downhaul tension. If some battens are under the mast as cammed sails are downhauled, one can damage the sail as the batten ends !snap! from under the mast as tension is applied.

Board Trim

Boards usually include three trim variables; footstraps, fins and mastfoot position.

  • Footstrap position determines the sailor’s stance on the board and therefore the board’s attitude in the water. Most boards have options regarding footstrap placement. Generally, a wide stance is control and maneuver oriented. For rough water/upper end footstraps placed forward and farther apart will result in more control over the board and the lift generated by the fin. On flat water both footstraps may be best located further back. Rear footstrap positions and straps set closer together will allow the windsurfer to fly more on the fin with less board in the water for greater speed potential. -Fins Deeper/bigger fins are well suited for light winds as they generate greater lift at lower speeds. As the wind rises shorter fins will make the board easier to handle. The fins angle to the bottom of the board will also affect performance. Vertical fins will make the board fly; better for lighter winds and speed. Sweptback fins will make the board easier to control in stronger winds and generally turn more easily but may detract from light and medium wind speed performance.
  • The Mastfoot is where the power and the ride meet so position is critical!.

Generally, forward placement increases board control by taking the sailor’s weight forward, more onto the board, controlling the fin.    Rear mastfoot positions are more speed oriented as the fin is allowed greater ability to lift the board; with more of the board out of the water speed potential is increased. The mastfoot set 137-140cm from the tail is a good “all-round” position from which to begin.

High wind trim package

If you feel overpowered set the mast and boom length to the recommended high- wind lengths and trim accordingly. Also try the boom lower by 2-4 cm and set the mastfoot further forward 1-3cm.    Hi wind trim will require the harness lines to move forward by 2-4cm compared to low wind trim.

Low wind trim package

To trim for power free the downhaul and the boom 2-4cm. Raise the boom a few centimeters and move the mastfoot back 2–3 cm. Low wind trim will require the harness lines to move back by 2-4cm compared to high wind trim. Experience the new sensations resulting from trim alternatives, and you will expand your windsurfing performance!


Windsurfing is a wonderful feeling of balance.    Should you feel unbalanced try one or more of the solutions listed. One of the solutions or a combination of them will bring balance for you!

  • The rig feels stiff and heavy with too much backhand power. ☺Try more downhaul& outhaul, mastfoot back, boom up, softer mast.
  • The board has the tendency to turn into the wind. ☺Try the mastfoot further forward, more downhaul, harness lines further back, footstraps further forward.
  • The board has the tendency to turn downwind. ☺Try the mastfoot farther back, higher boom, harness lines further forward, bigger fin, footstraps farther back.
  • The windsurfer feels in constant danger of being catapulted. ☺Try more downhaul, harness lines farther forward and farther apart, smaller sail, more outhaul, softer mast.
  • Slow, stuck to the water feeling. ☺Try the mastfoot farther back, boom higher, more downhaul, harness lines farther back and closer together, bigger fin, footstraps farther back, bigger sail, board with more volume.
  • Difficulty to get planning.
  • Try the boom higher, mastfoot farther back, bigger board & fin, bigger sail, harness lines back, less outhaul, footstraps farther back.
  • The board stands on the tail in strong winds (tailwalking). ☺Try more downhaul, more outhaul, mastfoot farther forward, smaller board & fin, footstraps farther forward, softer mast.
  • The board spins out easily. ☺Try more downhaul, more outhaul, straps further forward, bigger fin, mastfoot further back, softer mast.
  • Difficulty closing the sail down onto the board. ☺Try more outhaul, more downhaul, mastfoot further forward, smaller fin, softer mast, footstraps farther back, harness lines farther back, lower harness hook, smaller sail.
  • The board bounces in chop and when starting to gibe. ☺Try the mastfoot farther forward, boom lower, more downhaul, more outhaul, smaller fin, footstraps farther forward, smaller sail.