Even you check wind condition carefully and set up your gear, you could well encounter unexpected sailing feeling.
If you feel something bad, I would recommend get back to shore and adjust as soon as possible. You can adjust downhaul tension, outhaul tension, boom height, foot-belt, joint base position on a board and fin size by condition of wind and surface of the sea you saw. Keep adjust until you find best balance.

Batten tension

Batten tension could be different between each batens.
Battens from top to third, top to secound for 6 batten sail, should not be adjusted with high tension which causes bend. These battens are designed as letting out wind power by twist movement. Uunnecessary wind power will not let out from sail when these battens are bended. This causes sail top relatively heavy. On the other hand, battens beside boom, upper and lower, should be tighten to ensure stable centroid balance. However, please note that too much tension may have risk to break batten pocket.

Boom position

Attached position of boom would be different by wind condition or join base posion on a board, however we recommend boom position should be higher than 40% of luff length. (Note that each sail has different posion of sleeve cut) Body height should not be priority factor for deciding boom position. Lower boom posion makes sail relatively heavy which requires more downhaul tension for lightening a sail. This may reduce flexibility of a sail.

Two methods for treating in over sail condition.

Over sail condition:

Sail centroid ,power point, moves to backward by blustery wind and hand on a boom side cannot keep position. Finally, sail forcibly move to leeward.

Solution approach
Downhaul tension : Makes adequate bent by strong downhaul tension aiming to let out unnecessary power.
Outhaul tension : Zero to minus tension could be a basic way but plus tension is required depends on a sail characteristic.

Downhaul tension : Makes adequate bent by high downhaul tension aiming to let out unnecessary power.
Outhaul tension : Aiming to get easy handling by better twist with appropriate downhaul tension, outhaul tension could be either minus, zero or plus as you want.

Over sail by getting wind on leeward side surface(back wind) :
Unable to keep mast position as usual after blustery wind makes back hand, hand on the boom, heavy in a sudden, centroid forcibly move to frontward leg. This is mainly caused by getting unnecessary wind on leeward side surface.

Solution approach
If your Camber snap back easlity by pushing it by your hand, it may cause problem by back wind. You could put spacer in Camber root for getting Camber snap back more jumpy manner. Also, increase outhaul tension by pulling 1 to 2cm could be a solution for this unintended behavior.

Increase tension in both downhaul and outhaul(1 to 2cm). It is difficult to solve this problem only by downhaul tension adjustment.

Case study for getting more power and suppressing power

In example with two different size, 5.0u and 6.0u, sails do sailing at the same situation.

` 5.0u
Low response caused by less wind compare to sail size.

Solution : Adjust sail for getting more power.

  • Release downhaul tension 5mm
  • Release outhaul tension 5mm to 1cm. (No-cam sail case)
  • Tighten footbelt
  • To use upper side grommet in outhaul aiming to bring power at sail leech.
  • To use 2cm larger fin.
If you still feel under sail even you did above effort, you would better to consider size up a board or a sail.

a 6.0u
Planing enough but sail forcibly move leeward occasionally.

  • Increase downhaul tension 5mm.
  • Increase outhaul tension (No-cam sail only)
  • Move joint base on board to 1cm frontward. (Boom postion moves upper accordingly)
  • Release footbelt little.
  • To use lower side grommet in outhaul aiming to realize flexible sail leech.
Too much downhaul tension may reduce flexibility of a sail. Inflexible sail makes board control too sensitive. Sometimes board getting smooth by releasing downhaul tension. This sensitive sail works for powerful professional level windsurfer but it doesn't always work well for intermediate level windsurfers.

Downhaul tension

You can use sail printed spec as reference in first setting. But printed spec should not be considered as appropriate value always. Best suited value should be adjusted base on board size, fin size, wind speed, sea surface, air temperature and windsurfer condition.

Outhaul tension

No-cam sail could be adjusted from 0 to plus. Since suitable outhal tension may change by downhaul tension situation, it requires adjustment always.

Light wind condition tuning

In light wind condition, in general, sail with camber sail could be adjsted by downhaul and footbelt tension or choose lower or upper outhaul grommet, only when it has more than two grommet, while outhaul tension always keep same.
Depthless foil and tighter leech setting could be useful for faster planing start and keep sail powerful on gusty condition. Release downhaul tension and tighten outhaul tension 1 to 2cm makes tight and powerful leech. At a glance, looks deep foil is useful for faster planing but deep foil prevent wind current which prevents faster planing start. Tighter leech makes pumping more efficient by flexible mast whip which is realized by relatively loose downhaul tension.

Correlation between boom position and joint base position

People who is familiar with low boom posion feels unconfortable when he/she changes boom position relatively higher. He/She can keep same feeling even in higher boom position when move joint position frontward at the same time. Boom position and joint position should be adjusted together. It is necessary to find out comfortable boom position and keep that position in always.


Board control is greatly infulence by joint position, fin size and foot strap position. In addition, board control would influence to sail control.

Join position

Join position is relatively important for board control.
Join position could be adjusted for intending to increase or suppress board power. Also, fin grip performance is influenced by joint position. Joint position should be considered by board size, fin size, sail size and sea surface condition.
For example, when you change fin to smaller size due to over condition, it is better to move join position backward. If you don't change join position, you may face less up-wind power due to fin grip issue. Also, move joint position backward brings more control in rough surface condition by using fin power effectively.

For example:
Nose bouncing -> move joint frontward
Nose sticking -> move joint backward

[move joint frontward]

Reduce board nose vibration in over condition but possibility sticking to sea surface when continue to move frontward.

[move joint backward]

Backward joint position makes more floating power especialy in nose side. But it may cause uncontrollable vibration and jump when continue to move backward.

Board strap position

Board control and jive performance should be priority factor for considering foot strap position.
Relatively frontward strap postion makes jive easier for both man and woman. Since rail in nose side is used during jive, light weigh sailor better to put foot strap relatively frontward. Backward strap is better to put as closer as possible with board tail. Put pressure in closer to a fin is better for controlling. Position strap in inner side reduce strong blow adequateness and loose speed during jibe by nose lift up.