HOW to properly RAISE a DACRON Mainsail !!!!!!!!
Woven dacron mainsails are the most commonly found mainsails on ‘cruising’ boats. If you ‘just raise’ a woven dacron mainsail, you’ll most probably have sail trim and shape problems, problems that can adversely affect a boats performance, ‘helm balance’ and ultimately safety.
The following will outline what added steps are needed after a ‘boltroped’ dacron sail is raised - to get the ‘best’ out of the sail so you can have a ‘more forgiving’ and ‘less cranky’ boat.
Note – these directions are NOT for mainsails that are on in-mast roller furlers nor mainsails made of ‘laminates’.
Boltropes - theory.
Most woven dacron mainsails have a ‘boltrope’ at the luff; and, there are certain additional steps that should be taken after you ‘just raise’ such a sail, ......... as the ‘as designed shape’ of the raised sail depends a LOT on the tension in that boltrope.
The boltrope is a 3 strand dacron rope inside a ‘sleeve’ at the luff and it’s there to prevent the sail’s luff from ‘overstretching’ at the higher windranges – typically when the windstrength goes well above 12-15 kts. A woven dacron sail, without a boltrope will have the point of maximum draft constantly change its position, either fore or aft, with differing windstrengths; in light winds the draft will ‘go forward’ and in heavy winds the point of maximum draft will ‘go aft’. The boltrope is added to keep the point of maximum draft essentially in ‘one place’ under different windstrengths and to help keep the sail shape from stretching ‘all over the place’ under varying wind-loading.
When making such a sail, the sailmaker will purposely cut the boltrope a wee bit shorter than the ‘designed’ luff length, usually (for a sail typically designed for sailing in approx.15 kts.) will cut the boltrope shorter by approximately 1” for every 10-11 feet. of luff length. – this is called ‘boltrope preload’. So, to get to the ‘as designed’ luff length when raising such a sail, that boltrope has to be additionally stretched-out (by additional halyard tension, etc.) or the sail will not be ‘stretched’ to its intended ‘as designed’ SHAPE.
Boltropes – practicality.
For the sailor, this means that if you ‘just raise’ such a sail and want to sail in 12-15kts., the luff will be physically shorter than the ‘design’ by approximately 1” for every 10-11ft. of luff length; ..... therefore, you need to additionally ‘stretch out’ that boltrope so that the sail takes on its as DESIGNED shape!!!!!!!!!!
Without stretching out this ‘pre-load’ after ‘raising’ the sail, the sail will be draft-aft, ‘baggy’, too much draft, and the aft sections of the sail (leech) will be somewhat ‘hooked up to weather’ – all shapes that promote aggressive heeling, ‘powered-up but exceptionally slow’, poor ‘pointing’ ability, increased “weather helm”, etc. ..... very ‘cranky’ boat!!!
Remedy (Rx):
Raise the sail to just ‘up’, then apply an approximate additional 1” inch of HALYARD (and ‘cunningham’ if you have one) strain for every 10 ft. of luff length. Then go sailing on a hard BEAT to WINDWARD and notice the helm pressure (so-called ‘weather helm’). Crank on more (or less) HALYARD tension until you can take your hands OFF the wheel/tiller ... and have the boat go in a straight line (no heading up or down), all by itself — called a ‘dead fish neutral helm’. Then, slightly RELEASE some halyard tension until the boat ‘s-l-o-w-l-y’ heads up when you release the wheel/tiller ... the boat will now be FAST, wont heel as much as before, and will ‘point like banshee’. The sail will now have its point of maximum draft positioned correctly for the current wind and wave conditions ..... and you will better enjoy yourself.
Shrinking Boltropes .... a 'problem' with aged sails.
Dacron boltropes change shape over time and depending on HOW MANY TIMES they get ‘stretched-out’ ... and they progressively and additively get shorter and fatter. So, if it takes an immense amount of halyard tension to get to the ‘neutral helm’, etc., consider to take your mainsail to a sailmaker to get the boltrope adjusted or ‘eased’. Easing the boltrope will quickly and cost effectively bring an old ‘baggy’, powered-up, draft-aft sail ‘back to life and proper SHAPE’ ... and usually at minimal cost.
Another way to check for a shrunken boltrope: on a windless day, raise the sail to ‘just up’, add the additional 1” / 10-11 ft. of luff length by added halyard tension, then check the angle that the top of the boom makes with the mast at the gooseneck. If that angle is much greater than 90 degrees ... say 95 to 100 degrees, it means that the boltrope has shrunken and should to be readjusted or ‘eased’.
Most boats with ‘shrunken boltropes, or improperly raised boltroped mainsails, will visually have the aft end of the boom LOWER than the gooseneck!!!! .... probably 95% of all cruisers & ‘non-racing’ sailors will have a ‘droopy’ aft section of their boom.
Once you have the proper basic ‘as designed’ SHAPE in your mainsail by properly RAISING it, etc. (by stretching out that boltrope!!!!) which brings the point of maximum draft to the ‘correct’ fore/aft position, all the ‘other trim and shaping’ efforts will be ‘much’ easier and more ‘effortless’.
Woven dacron mainsails are the most commonly found mainsails on ‘cruising’ boats. If you ‘just raise’ a woven dacron mainsail, you’ll most probably have sail trim and shape problems, problems that can adversely affect a boats performance, ‘helm balance’ and ultimately safety.
The following will outline what added steps are needed after a ‘boltroped’ dacron sail is raised - to get the ‘best’ out of the sail so you can have a ‘more forgiving’ and ‘less cranky’ boat.
Note – these directions are NOT for mainsails that are on in-mast roller furlers nor mainsails made of ‘laminates’.
Boltropes - theory.
Most woven dacron mainsails have a ‘boltrope’ at the luff; and, there are certain additional steps that should be taken after you ‘just raise’ such a sail, ......... as the ‘as designed shape’ of the raised sail depends a LOT on the tension in that boltrope.
The boltrope is a 3 strand dacron rope inside a ‘sleeve’ at the luff and it’s there to prevent the sail’s luff from ‘overstretching’ at the higher windranges – typically when the windstrength goes well above 12-15 kts. A woven dacron sail, without a boltrope will have the point of maximum draft constantly change its position, either fore or aft, with differing windstrengths; in light winds the draft will ‘go forward’ and in heavy winds the point of maximum draft will ‘go aft’. The boltrope is added to keep the point of maximum draft essentially in ‘one place’ under different windstrengths and to help keep the sail shape from stretching ‘all over the place’ under varying wind-loading.
When making such a sail, the sailmaker will purposely cut the boltrope a wee bit shorter than the ‘designed’ luff length, usually (for a sail typically designed for sailing in approx.15 kts.) will cut the boltrope shorter by approximately 1” for every 10-11 feet. of luff length. – this is called ‘boltrope preload’. So, to get to the ‘as designed’ luff length when raising such a sail, that boltrope has to be additionally stretched-out (by additional halyard tension, etc.) or the sail will not be ‘stretched’ to its intended ‘as designed’ SHAPE.
Boltropes – practicality.
For the sailor, this means that if you ‘just raise’ such a sail and want to sail in 12-15kts., the luff will be physically shorter than the ‘design’ by approximately 1” for every 10-11ft. of luff length; ..... therefore, you need to additionally ‘stretch out’ that boltrope so that the sail takes on its as DESIGNED shape!!!!!!!!!!
Without stretching out this ‘pre-load’ after ‘raising’ the sail, the sail will be draft-aft, ‘baggy’, too much draft, and the aft sections of the sail (leech) will be somewhat ‘hooked up to weather’ – all shapes that promote aggressive heeling, ‘powered-up but exceptionally slow’, poor ‘pointing’ ability, increased “weather helm”, etc. ..... very ‘cranky’ boat!!!
Remedy (Rx):
Raise the sail to just ‘up’, then apply an approximate additional 1” inch of HALYARD (and ‘cunningham’ if you have one) strain for every 10 ft. of luff length. Then go sailing on a hard BEAT to WINDWARD and notice the helm pressure (so-called ‘weather helm’). Crank on more (or less) HALYARD tension until you can take your hands OFF the wheel/tiller ... and have the boat go in a straight line (no heading up or down), all by itself — called a ‘dead fish neutral helm’. Then, slightly RELEASE some halyard tension until the boat ‘s-l-o-w-l-y’ heads up when you release the wheel/tiller ... the boat will now be FAST, wont heel as much as before, and will ‘point like banshee’. The sail will now have its point of maximum draft positioned correctly for the current wind and wave conditions ..... and you will better enjoy yourself.
Shrinking Boltropes .... a 'problem' with aged sails.
Dacron boltropes change shape over time and depending on HOW MANY TIMES they get ‘stretched-out’ ... and they progressively and additively get shorter and fatter. So, if it takes an immense amount of halyard tension to get to the ‘neutral helm’, etc., consider to take your mainsail to a sailmaker to get the boltrope adjusted or ‘eased’. Easing the boltrope will quickly and cost effectively bring an old ‘baggy’, powered-up, draft-aft sail ‘back to life and proper SHAPE’ ... and usually at minimal cost.
Another way to check for a shrunken boltrope: on a windless day, raise the sail to ‘just up’, add the additional 1” / 10-11 ft. of luff length by added halyard tension, then check the angle that the top of the boom makes with the mast at the gooseneck. If that angle is much greater than 90 degrees ... say 95 to 100 degrees, it means that the boltrope has shrunken and should to be readjusted or ‘eased’.
Most boats with ‘shrunken boltropes, or improperly raised boltroped mainsails, will visually have the aft end of the boom LOWER than the gooseneck!!!! .... probably 95% of all cruisers & ‘non-racing’ sailors will have a ‘droopy’ aft section of their boom.
Once you have the proper basic ‘as designed’ SHAPE in your mainsail by properly RAISING it, etc. (by stretching out that boltrope!!!!) which brings the point of maximum draft to the ‘correct’ fore/aft position, all the ‘other trim and shaping’ efforts will be ‘much’ easier and more ‘effortless’.
