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Setting the Phantom Sails

Setting Phantom sails presents the same issues as setting other flat panel sails and is little different from setting normal panel sails with the added problem that all curvature of the sail is supplied by the curve in the foot.  In a flat panel sail the curvature introduced this way will allow at least 2/3-3/4 of the sail to have some draught although the top 1/3-1/4 will still tend to fall off readily.  In some ways in a tender vessel like the Phantom, this may not be too much of a disadvantage as the heeling forces generated by the top section of the sail will be small and like wings in model aircraft represent 'washout' and helps prevent the top of the sail from stalling and reducing drag associated with it.

It may well be worth your while referring to the Sail Modification section to see if your set of sails will set properly anyway before you go to the trouble of rigging them on the spars.  This presents the issue of a correct luff curve on the sails - essential in a flat panel sail!

Additionally the mast join 3/4 of the way up the mast is critical.  Any slack at this joint will allow the top of the mast to fall back when backstay tension is applied.  This critically affects any luff curve you may have in the sail as it now has to match a mast with still more curve.  Get your mast straight and glue a strong joiner into the mast to connect the two sections.  A piece of timber trimmed to shape or better still some a section of fibreglass etc is much much better than the plastic joiner supplied.  Don't get any glue in the sail track though!!  This was the first thing to break on my boat.  Thanks to Jordy and Doc for reminding me of this issue.

Unfortunately the sail setting options supplied by Phantom leave a lot to be desired.  This article outlines one way to ensure you get the best from your sails.


The luff, tack and head fittings and attachment points are fairly basic but work OK.  It is the clew and fittings at the end of the boom that causes the problem.  Most yachts I have seen just use a line from the hole in the end of the boom fed through the clew and the sail, back through the hole and onto the tie position.  This has some good points and bad points!  The good is that fed this way, the clew of the sail will be controlled by a 2:1 system which allows finer tuning of the clew of the sail.  The bad is that the angles are all wrong!  The sheeting angle is so low that the sail foot is pulled tight leaving no shape or camber in the foot thus no curve can be introduced to the sail above.  Such a flat sail will not generate any substantial lift when beating to windward though it will work fine running and even reaching where an airfoil shape is not quite as essential.

To get the clew sheeting angle correct and to make it adjustable, the easiest fitting to use is a small ring - 5mm from a fishing shop and a cable tie to secure it.  Wrapped around the boom and pulled tight with pliers will hold the ring in place and allow both to be slid along the boom to give fine adjustment. The sheeting line is fed through the ring as in the diagram below.

Really that's all there is to it.  Adjusting the ring will allow more or less camber in the foot.  Adjusting the tension in the clew line will adjust the amount of tension in the leech hence the amount of twist in the mainsail.

You should be aiming for about 8-10% of camber at the foot as it will decrease up the sail because its a flat sheet of sail cloth.  This corresponds to a depth of 25-35 mm of depth in the foot - about 2 finger widths.  Most sailors I have seen have had a camber of 0%!  No wonder the yachts stagger to windward.  This might seem like a fair bit of camber in a sail so what about pointing?  A sail with 10% camber will not be able to point as high as one with say 6% but the Phantom is heavy, has a small keel area and will make excessive leeway if you try to point too high.  Better to free off a little, foot faster and get to windward quicker.


The jib is sightly different because the main boom has a boom vang to hold the boom down and tension in the clew line will tension the leech as much as you wish as the boom cannot lift up because the vang is holding it down.  The problem is the a little different in the jib boom.  Because it is pivoted about 20% of the foot length back from the tack, tension in the luff generated by backstay tension causes the clew end of the boom to forced down generating tension in the leech of about 1/4 the tension in the luff.  In light winds this will pull the leech tight causing the leech to curl back, the gap between the jib and the sail (the slot) to close, stalling the sail and reducing drive.  In stronger winds the force of the wind will lift the boom and open the slot.  This means some means of supporting the boom in light winds is essential.  The normal method is to use a topping lift - a light line connecting the clew end of the boom to the forestay attachment position on the mast.  An adjustable sliding latching device  (a bowsie) can control and adjust this lift to maintain the desired slot in the lighter winds.


As in the main sail, the angle of the pull by the clew line must be adjustable to get the correct angle.  It is easier in the jib as the downward force is already present so a simple loop through the clew and around the boom will hold the clew of the sail fixed in a horizontal direction while the normal clew line can be used to hold the clew out towards the end of the boom.  These two forces act together to give the required force on the clew.  Once again the foot of the sail should have an 8%-10% camber (25mm-30mm) to give the sail an airfoil and generate drive into the wind.

If despite all this work the sails still do not set at all nicely then you may need to look at the sail modifications and check those luff curves again as this is critical to getting a nicely shaped sail with an efficient airfoil.

Mainsheet and Jibsheet settings

Now that the sails set properly, its time to think about the final settings of the main and jib sheets.  As a guide, the mainsail is set with the boom at about 5 and the jib about 10 when the sails are pulled fully in.  For the main boom this represents when the end of the boom is about 25mm -35mm from the centreline of the yacht and about 55mm - 60mm for the jib boom (roughly pointing towards the shrouds).  If you try and pull them in any tighter than this then you may point a little higher but leeway will increase as your speed decreases.

This is relatively easy enough to achieve by judicious adjustment of the sheets coming from the winch.  However a major problem arises when the sails are let out.  It is a good idea to have an adjustment mechanism on the end of the sheets so they can be set accurately to that point.  I like to tie a small loop on the end of the sheet after feeding it through the boom attachment point and then held in place by a cable tie around the boom through the loop.  The cable tie is pulled tight enough to hold but still able to be slid along the boom.  Simple and easily adjusted.  If tie is too loose either replace it or add another.

As the wind increases, the Phantom heels readily and develops excessive weather helm.  Increasing the sheeting angle of the main up to and even beyond the 10 degrees may be necessary to maintain control. This means the jib becomes the main driving force in these conditions  - time to change to a 'B' rig


page last edited on 19/12/2011