SQUIB: Rig tune and trimming

Here is some advice about how to get the best from the Squib rig. These notes are specifically based on our personal experience and that of many successful owners of BATT Squib sails.

Sail settings are just part of the recipe for consistently good boatspeed. Many elements of boathandling and sail trim. Alert response to changing apparent wind speed and direction play a leading role. For this reason these notes refer in part to these techniques, as well as tuning and sail adjustment.

CLICK HERE to see the rig set-up diagram

OUTHAUL
Upwind
Particularly when you set the boom on or very near the centreline, the foot of the sail should stretched tight using the outhaul. In particular the clew should be out to the measurement band for extreme light winds and when you are overpowered in strong winds.

Racing on flat water have the outhaul tight. Remember that it can pay to ease the mainsail clew 20mm - 40mm in from the measurement band for extra drive when sailing upwind in choppy conditions.


Offwind
a) In light or moderate winds. On a beam or broad reach the outhaul can be eased up to 75mm for extra sail fullness and power. On a dead run this makes less difference to boat speed. It makes most difference to boat speed when surfing conditions exist.
b) In VERY strong winds . Only ease the outhaul offwind if you can easily reach the string. You will have other priorities!

CUNNINGHAM
Upwind
a) In light and medium conditions: Pull only just enough tension to almost eliminate horizontal creases near the luff. A few creases do not matter. Set like this the sail will develop its maximum power.
b) For stronger wind: Extra tension on the cunningham straightens and flattens the upper part of the leech, helping it twist more readily to spill unwanted power. The more cunningham tension you apply, the more easily the sail will twist open for a given gust of wind. The sail responds more easily to gusts, but give less power.
REMEMBER: More luff tension = less power, Less luff tension = more power.
Offwind - In all wind conditions - Release the cunningham completely.

MAINSHEET TRAVELLER It is an advantage to be able to easily set the traveller at the windward end of its track. This makes it possible to set the boom on the centreline at will. If the boom is centred, more sail twist is needed to keep the upper leech telltails flying.

In gusty conditions, dumping the traveller to leeward momentarily takes the 'bite' out of a gust. The traveller can almost immediately be hauled back. The boat accelerates into the gust instead of heeling and stalling. Similarly it can pay handsomely to exit a tack with the traveller 'down', to encourage acceleration.

BACKSTAY
For very light winds prebend the mast 40mm with the backstay. This prebend is overidden by natural mast bend in medium winds, and the backstay should be left slack. Only use backstay sparingly as a final resort to depower the mainsail. Too much too soon and pointing ability suffers dramatically. Offwind ease it completely.

MAINSHEET
Beating
a) Light to moderate winds:
Allow just enough sail twist for the tell tails on the upper leach to fly nicely. With too much sail twist the tell tails will stream too easily You are losing drive and/or pointing potential. With too little sail twist, the tell tails will be sucked out of sight behind the sail. You are creating unwanted drag. Ease the mainsheet until the top tell-tail just reappears.
b) Strong winds You are overpowered. Forget the leach tell tails and just worry about flattening and twisting the sail (tighter mainsheet, tight outhaul, tight cunningham, some backstay) as necessary to lose power. A flatter sail is less powerful, and will also twist more readily to spill power.
VANG (Kicking Strap)
In very light winds you must have almost no tension on the vang, or the leech will not be free to twist a little the sail will be 'constipated' and the boat will feel dead and unresponsive. The sail needs to twist a certain amount to allow air to flow freely off the leech, encouraging an efficient airflow across the whole sail.

Reaching and running. A sail with some twist is fast, but tends to make for less stability, particularly running. If the boat rolls unacceptably, use extra vang to reduce twist, and/or sheet the boom closer in. It is faster to sail unsteadily with a twisting sail than it is to overtrim the sail to inhibit rolling. This can involve a compromise between speed and steadiness in very strong winds.

BOOM ANGLE
Beating:
a) Until you are overpowered, the boom should be on or near the centreline of the boat.
b) As the wind rises flatten the sail progressively with the mainsheet, the cunningham and eventually the backstay as much as necessary. Only if you still cannot keep the boat upright and driving, then be prepared to set boom at a greater angle to the centreline, to reduce heeling.
Sailing in waves it can pay to set the sails at a slightly greater angle to the centreline than you would do for the same windstrength on flat water. Use slightly fuller sail settings and allow more twist in the upper leeches.
In light, steady winds on flat water your performance may benefit from bringing the boom and the jib sheet barber hauler, a bit closer to the centreline than normal, and using a correspondingly flatter sail setting. The sails will need less twist. This needs precise helming. If in doubt, ease it out!

JIBSHEETING
A good starting point for the fairlead position is shown in the diagram. In light to moderate winds have the barber hauler pulled right into its datum position, and from here sheet tension is the principal control of jib set for different winds. With the sail setting correctly the jib foot will sit about 150mm inside the rail, level with the mooring cleat. If the fairlead is too far aft the sail foot will crease and flap. No fairlead adjustment is needed for different wind strengths once the right position has been established. However, if for stronger winds and / or in choppy water the boom is set further out, you should also consider easing the jib barber haulers .

Offwind the barber haulers should always be eased almost to the shroud. If their control lines are linked together they will both adjust as one.

JIB HALYARD
In light winds (crew not sitting out) have the jib luff hanging at the same tension as the forestay. More jib halyard tension in medium wind, less in light wind. In strong winds some people get very good speed by easing the jib halyard considerably to get more mast rake. (They have a slacker forestay in light/medium winds). They then need to use more mainshheet tension to control jib luff sag. This does not suit all sailors. Some jib luff sag is normal and the sails are designed to cope with this.

TROUBLE SHOOTING
Some possible problems and their common causes:

PROBLEM	POSSIBLE CAUSE	POINTS TO OBSERVE
Slow upwind in light winds	Not enough sail twist.	Is vang or mainsheet or jibsheet too tight? Check top leech telltail
	"Pinching"	Watch luff tell tails.
	Sails too full Is outhaul too eased?	Are fairleads too far forward? Not enough sail twist. Try some backstay Try traveller to windward
Not pointing in normal conditions	Too much sail twist.	Is vang, mainsheet or jibsheeet too slack? Are fairleads too far aft?
	Too much mainsail twist.	Is cunningham too tight?
	Boom too far outboard.	Traveller position
	Fairleads too far from centreline	Barber haulers in.
Slow offwind in light winds	Whole mainsail stalled	(mainsheet not eased enough)
	Jib overtwisting	Ease barber haulers
	Jib stalled	Watch telltails on lee side
	Top of mainsail stalled (not enough twist)	Is vang too tight?
	Spinnaker unsteady	Check pole height.
Slow offwind in stronger winds	Too much sail twist	Is Cunningham still tight?
	Too much sail twist	Is backstay still on?
	Sails stalled	Watch luff telltails on lee side.
	Spinnaker overtrimmed	Check pole height. Nag crew.
	Spinnaker 'twitchy'	Change pole height
	Crew twitchy	Change crew!

Conditions can be expected to change frequently during most races. A well tuned and set up rig will accomodate many of these variations automatically, particularly in stronger winds. Be aware that an alertness towards potential sail and boat trim adjustments often reaps large dividends in efficiency. If you are thinking that a sail adjustment may be needed, the chances are that you should already have done it! You can always change it back
...................................................................................... .

Don't be afraid to experiment with sail settings. The principles outlined here can form a reliable foundation from which to develope your own techniques and preferences for getting the best from your rig. Please let us know if you have any questions arising from these notes.

SPINNAKER HINTS

If one part of your spinnaker luff collapses before the rest, something is wrong.

With the pole height correct the luff of a good spinnaker will 'break' (i.e. progressively collapse at the luff) the majority of its height at the same time, and will fly steady with the sheet considerably eased compared with a sail either set or cut incorrectly.

If the spinnaker will set with its sheet more eased, then so can the jib and mainsail without suffering backwinding. Keep all the sails setting but keep them as far off the centreline as possible, and you create a rig strong on drive and acceleration, low on heeling and drag. If the spinnaker is oversheeted, then so will be thejib and mainsail, and nothing destroys boatspeed on a reach more effectively than oversheeting the sails .

There is a very simple rule. If the luff is not 'breaking' evenly for most of its height, the spinnaker pole's outer end should be tilted towards whichever end of the luff is collapsing first as the sheet is eased:

If the UPPER luff collapses, UP should go the pole end.
If the LOWER luff collapses, LOWER the pole end.

Set your pole height to this rule on a shy reach on a manageable day and it will be fine for all points of sailing in most conditions. Do not worry too much about the position of the inboard end of the pole on the mast, it is the height of the outer end which really matters.

Some final points:

1. Have a slightly lower pole setting for very light airs, to keep the sail more symmetrical when the clew cannot be prevented from drooping.

2. 'Kevlar' or 'Spectra' sheets make a huge difference to setting the pole effectively near the forestay in stronger winds. The Squib spinnaker guy is very long, and even a small percentage of stretch is unacceptable.

3. Less kicking strap and loads of mainsail cunningham will help you carry the spinnaker on a windy shy reach. 'In extremis' use the backstay too. Keep the JIB sheeted 'loose'.

4. Do not raise the pole end in strong winds. It does not help.

6. Many sailors worry a great deal about hoisting, lowering and gybing their spinnaker, but pay less attention to setting up the sail correctly for speed. Pole height is the key.

© BATT SAILS 2000