The Headsail
Last month we focused on the mainsail but in this article we discuss the real driving force in the yacht’s rig, the foresails.
Dependent on the wind angle, 60-65% of the sail power will be generated by the foresails, especially in the case of the Genoa. Additionally, if you trim your headsail and mainsail well together the two sails form a ‘slot’, significantly improving the balance of the boat.
As with the mainsail, depth and twist are the adjustables to power in the headsail. Tightening up the backstay also tightens the forestay, making the sail flatter, taking out the sag and allowing the sail to cut closer to the wind. Easing it does the opposite and by bringing the luff closer to the leech, makes it ‘deeper or fuller’
A flatter sail is better when you are hard on the wind. A deeper sail shape is better downwind. The forestay will sag more as the wind increases, requiring more backstay tension. As the wind drops, ease the backstay to keep power on.
Note: If the forestay is too loose the foil of the furling system may be damaged as it is rotating to furl the sail.
The jib or genoa cars move along deck tracks. By moving the car forward you make the sail deeper and decrease twist. Whilst this change of shape is necessary, we must also consider the balance between the leech and foot of the sail, and the car will need to be in a different position according to how furled the foresail is too.
Imagine drawing a line from your jib car through the clew of the sail to the luff: It should be around 35 per cent up the luff for the correct position.
What you are trying to achieve is equal tension/balance between the foot and the leech. If the foot is too tight and the leech to loose, air will spill out of the top of the sail. If the foot is too loose, air will spill out of the bottom of the sail. In heavy weather, if the leech of the sail is loose and flapping, the life of the sail will reduce rapidly.
Note: If the forestay is too loose the foil of the furling system may be damaged as it is rotating to furl the sail.
The jib or genoa cars move along deck tracks. By moving the car forward you make the sail deeper and decrease twist. Whilst this change of shape is necessary, we must also consider the balance between the leech and foot of the sail, and the car will need to be in a different position according to how furled the foresail is too.
Imagine drawing a line from your jib car through the clew of the sail to the luff: It should be around 35 per cent up the luff for the correct position.
What you are trying to achieve is equal tension/balance between the foot and the leech. If the foot is too tight and the leech to loose, air will spill out of the top of the sail. If the foot is too loose, air will spill out of the bottom of the sail. In heavy weather, if the leech of the sail is loose and flapping, the life of the sail will reduce rapidly.
The telltales on the sail will quickly show you if your sail is out of balance. If they point up, the leech is too loose, if they point down, it’s too tight.
Bow-down Speed-building Mode
Leeward tellatle dances and windward telltale streams straight back. This mode is used for building speed when coming out of a tack or when going through steep motorboat wake.
Max Speed
Mode
Both telltales
streams straight aft.
Pointing
Mode
Leeward telltale streams aft, and windward telltale dances between straight back and 45° above horizontal. This mode is used when sailing to windward in flat water in winds over 10 knots.
Pinching
Mode
Leeward telltale streams aft, and windward telltale stands straight up. To be used when trying to get over another boat or make it around a channel mark.
If the leech is too loose, move the car forward, if the foot is too loose, move the car back further aft.
A consideration at this point is the question we get asked at Kraken very often.‘Can a Kraken have a self tacking jib?’
Yes, it could, but we won’t put one on. The reason, which you may realise if you consider the above sail trimming explanation, is that you cannot properly reef the sail, and in a Solent rig the reefed, or furled, jib is your heavy weather foresail. Since a self tacker doesn’t have fore and aft tracks, or cars, as you furl the sail, as you must in heavy weather, the leech will go loose and the foot will go tight. This means in heavy weather, you will have a nasty flapping leech which will quickly destroy the sail.
By tightening the sheet you decrease the twist and power up the sail to allow the yacht to point higher. By easing the sheet, you create the opposite effect – more speed, but less pointing ability.
The skill of a good sailor is to get the sheet and therefore the sail set right. If the sail is too tight or hard to the wind, it will drive the yacht less well and create more and unnecessary heel. If too slack, the power of the wind will be lost and the yacht will slow down.
Telltales, right on the leech of the foresail, will be at right angles to the sail so ease the sheet.
If the same telltales are disturbed and fluttering in towards the upwind side of the sail, the sail is too loose and the sheet should be tightened.
Telltales are the simplest guide to efficient airflow and correct trim:
Leeward tell tales stalled:
Ease jib sheet
Windward tell tales lifting:
Tighten jib sheet
Windward upper telltale lifting:
Move jib car forward
Leeward lower tell tales stalled:
Move jib car aft
All telltales flowing horizontally:
Don’t touch!
An easy way to determine whether you’re under or over sheeting your sails is to come up from your course to windward by 5º, leaving the sheets where they are. If your boat speed increases, you had your sheets too tight, same dropping down wind by 5º, if the yachts speeds up you had your sails too loose.
Look also at how much helm (rudder angle) the yacht needs to hold her on course.
If it needs more than a 2 or 3 degrees of rudder you need to re-balance the sails. First try just easing the mainsheet, this will reduce the yachts lead, thereby reducing the weather helm and she becomes more balanced. If in doing that the mainsail begins to luff a bit, but the yacht feels more balanced, the answer is to reduce some of the mainsail then trim the sail back to a good set.
Play about with the sails, sheets and the track car positions on days when the wind angle and speed is constant, you’ll be surprised how a tiny adjustment can put an extra knot on your boat speed. It’s a good idea to practice sail trim on autopilot so you have a more constant course and can more easily identify small adjustments to the sheets and car positions.
When the sails are trimmed properly, at the helm, you will feel that you are ‘in the groove’. The boat will be noticeably going at her best, will be easier to steer, and will have less heel, result satisfaction and a big smile.
