Nordic Folkboat Tuning Guide for Aluminium Masts

  • Last Updated: October 6, 2020
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The purpose of this tuning guide is to provide our clients with standardized guidelines on how to get the most out of their new North Sails Folkboat sails. This guide was written by Soren Kæstel, Per Jørgensen and Theis Palm.

Follow these instructions as closely as possible. However, it is always a good idea to experiment. Your boat, the weight of the crew, the boat’s balance as well as local conditions will also affect the optimal trim.


The mast on a Folkboat is probably the most critical component of the boat’s trim, especially with the introduction of the class-legal aluminum mast. The aluminum mast has the proper stiffness. Therefore, it is important that these trim instructions are followed carefully in terms of how much pressure the mast applies to the aft edge of the mast hole.

1 Verify that the mast is vertical. This is best done by moving each shroud along the mast and make a mark on the shroud that matches the top of the gooseneck mark. Reattach the shrouds to the chainplates and measure from the mark to where the turnbuckles enter the deck – the distance should be the same on both sides.

2 Set the mast rake. Detach the forestay from the deck and place it along the mast. Stretch the wire as much as possible and make a mark that matches the top of the gooseneck mark. Reattach the forestay. The mark should be 1.31 m from the deck along the forestay.

3 Position the foot of the mast. Move the foot of the mast aft until the mast just touches the aft edge of the mast hole. In light winds (0-8 knots) the mast should be relatively hard on the aft edge and pressed 22 mm aft along the mast foot rail for the mast to bend smoothly. In the wind 9-14 knots of wind, press the foot of the mast 16 mm astern and in strong winds 10 mm astern.

4 Adjust the jumpers. Pull-on the backstay. Look up the sail track and make sure that the mast is straight and the jumpers are equally tight. If not, adjust the jumpers until the mast is straight. Jumpers are set relatively loose in light winds and strong winds. In medium winds, tighten the common turnbuckle 2-3 turns. The maximum draft in the top of the mainsail should be 47% aft along the chord. The most important thing is that the mast curve is even from deck to top. If the jumpers are too tight, the mast will curve too much in the bottom and be too straight in the top. If the jumpers are too loose, the bottom will be straight and the top will curve if the jumpers are set to loose. A consistent curvature gives the leech a nice, even twist.

5 Set the forestay tension. Initially, the mast hole helps to push the mast forward and thus get the forestay loose. In light wind the forestay should sag about 8 cm. Tighten the shrouds while sailing until the 8 cm sag is obtained. In medium wind, tighten the shroud turnbuckles 1½ turns and a further 1½ turns in strong wind, thus tightening the forestay under increased wind pressure.


The mainsheet is critical in setting the shape of the sail and small adjustments can have a big effect on speed and pointing. If the mainsheet is sheeted tight, the leech will close and put more pressure on the rudder – on the other hand pointing ability is improved. This can be used in medium winds and flat water, where the boat can be kept flat by hiking.

In light winds the mainsheet is eased so that the top tell-tale flies straight. In heavy winds, sheet tight and pull the backstay until the rudder feels light again (but without losing pointing). In large waves, let the leech twist a little more to have a wider steering angle. This increases speed, and therefore pointing, at the same time. As a thumb rule the top batten is trimmed parallel to the boom in almost all wind strengths.

1 Outhaul. The outhaul is also an important factor when trimming as it controls the draft in the bottom of the sail. In very light winds (0-5 knots) the sail should be 3 cm from the mark. In medium winds (5-12 knots) about 1.5 cm from the mark and
in more wind than this pull the sail all the way to the mark.

2 Cunningham. Do not set the cunningham in light winds. In medium winds set the cunningham so that the wrinkles in the luff disappear. When the wind exceeds 15 knots it is pulled hard to open the leech and keep the draft forward in the sail.

3 Traveller. It is a good idea to have two cars on your traveller. They are then connected by two wires of about 40 cm leading to a mainsheet block. This facilitates sailing in light and medium winds. In light winds (0-6 knots) pull the traveller cars 15-20
cm to windward. In medium winds (6-14 knots) set them in the middle. In higher wind the cars are eased to leeward to decrease heel and thus rudder pressure.

4 Backstay. The backstay has two functions: To control draft in the mainsail and to control forestay sag. When the backstay is tightened, the mainsail flattens, the leech opens, and there is less forestay sag and, therefore, a jib with less draft. It is a
good idea to put marks on the backstay, e.g., every 20 cm, to facilitate finding the right trim after mark roundings, etc.

5 Kickingstrap / Boom Vang. The kickingstrap is used when sailing upwind in strong wind and also downwind. Upwind, the kickingstrap pulls on the mast and opens the leech in the bottom part of the mainsail and keeps the boom down when easing in the gusts. Never use the kickingstrap upwind in less than 18 knots and use caution. Remember always to ease the kickingstrap for downwind sailing when bearing off, otherwise the boom might break. Downwind the kickingstrap is trimmed so that the top batten is parallel to the boom – on all sailing angles and in all conditions.


North Sails jibs are made for sheeting points both on deck and cabin top. However, we recommend sheeting from the cabin top to make the jib-leech twist more freely and thus allowing the gap between main and jib to be as wide as possible. Furthermore, the control of the jib is improved (particularly in heavy winds) because of the shorter distance from clew to block. The jib-lead track is placed with its centre 58 cm from the boat’s centreline. When sheeting from the cabin top, we recommend using a swivel block on the deck, so that the jib sheet does not create an overwrap on the winch.

1 Sheeting Point. The position of the jib lead is crucial for the jib trim. As a reference point measure 2.65 m from the pin in the forestay to the centre of the block (if the lead is on the cabin top). The jib shall luff evenly, i.e. tell-tales must fly at the same time in
top and bottom.

2 Jib Sheet. As a general rule sheet the jib so that the middle batten is parallel to the centreline in most conditions, but in light winds (0-5 knots) leave 2-3 degrees of twist. If the sea is lumpy, move the jib lead two to three “holes” forward to get
more draft and power in the jib (the middle batten shall still be parallel to the boat’s centreline). In heavy winds move the lead on to two “holes” back without letting the foot of the sail become loose and flutter.

3 Halyard Tension. Never pull the halyard too tight. This will cause the draft of the jib to move too far forward. Pull it until the wrinkles in the luff disappear. In light wind the best shape is obtained when leaving small wrinkles in the luff.

Please get in touch with Theis Palm for any more information.


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