awkward sail trim

[bstaff2]

Hi Don,
As you can see in the attached pic of our '82 Islander, the Blue Moon, we have an awkward mainsail set. We lost 2 battens, but will replace them soon. What is causing the pull in the sail? Is our boom too high, too low? Something else? Outhaul? The topping lift? We are fairly novice sailors (stating the obvious), but would love to hear your advice.
Barb

 

[Clark]

Hard to tell from the picture but it looks like the lower 2 battens are the missing ones? With that said, verticle/diagonal wrinkles from the clew usually means the clew is pulled too far down by the mainsheet + vang. Replace the battens and ease your mainsheet a little - compensate for loss of attack angle with your traveler and try that. It should help.

 

[RichH]

Those 'girts' (apparent creases) running from the clew toward the head are probably: result of the leech being unsupported by battens (missing battens). With battens supporting the roach (leech extension) the 'girts' should disappear.
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If the 'girts' dont disappear with the proper battens installed, then apply MORE halyard tension, until the boom (the 'sailside' of the boom) and mast make an approximate angle of 89 degrees. The picture isnt all that clear; but, the mainsail may be 'just raised' and doesnt have the 'luff boltrope' stretched out .... typically you need to additionally 'stretch out a luff' on a boltroped sail by approx. 1" for every 11 ft. of luff length (this for 15 kts. of wind), less halyard tension in 'light winds', etc. ..... this halyard tension will 'trip' or 'open' the leech, thus removing a lot of edge tension in the leech (and will release or lessen the 'girts').

If the sail is properly cut/made, 'girts' will usually appear along the edge that has too much tension. Remedy: ease tension on the edge that has the 'girts' OR increase tension on the side(s) OPPOSITE of the long axis of the 'girts'. Its OK to have small 'girts' radiating from the 'corners' of the sail; but, not across several panels.

If the installation of the proper battens doesnt cure the 'girts', take a picture while shooting 'up' at the sail with the camera held under the boom ... while on the floor of the cockpit or cabin top. ;-)

 

[bstaff2]

Thanks so much for your help. It is the 2 lower battens that are missing. We bought new ones and will install them in the spring. Also, we'll try adjusting the mainsheet halyard, vang and/or boom, if necessary. BTW, what does "boltroped" mean?
Barb

 

[RichH]

Most common sails made from woven dacron have a 3-strand dacron 'rope' inside a sleeve at the luff (and sometimes along the foot). The boltrope is there to prevent the sail from stretching out of shape and 'powering up' in the higher wind ranges. The stretch of the boltrope is well known and very predictable to sailmakers, who intentionally cut the boltrope shorter than the sails luff/foot dimensions.

When raising such a sail, you should stretch out this 'pre-load' on the luff for the sail to take on its 'as designed' shape; otherwise the luff will be 'too short', the leech will be hooked or 'curved up to the weather side' - not 'flat', the draft will be too far 'aft' in the sail, and the aft portion of the boom will be lower than at the gooseneck (connection of the boom to the mast).
If you 'just raise' the boltroped sail and dont additionally 'stretch out' the luff boltrope you get: aggressive heeling, slow boat, and the helmsman will experience too much 'weather helm'.

When setting up a boat for the days conditions - go onto a hard beat to windward and notice the helm when you release it from your hands. If the bow starts to point up to the windward side = weather helm. You then set the tension in the luff boltrope by the halyard, increasing that halyard tension until the boat will sail in a straight line and without 'turning up' or turning down when your hands are off the helm --- it goes dead straight. Once you have found 'neutral helm' where the boat wants to sail 'straight as an arrow' with no hands on the helm, .... then slightly DECREASE the halyard tension until the boat 's-l-o-w-l-y' turns to windward (very slight weather helm) .... and the boat will be faster, heel less, and will be more responsive overall.
Note: once you find the 'sweet spot' of proper halyard tension (slight weather helm) ... mark the mast and the halyard (electrical tape is good) and if sometime later when you go sailing and the conditions are equal, then just match or 'line up' the two marks on the mast and halyard for your 'normal' sailing conditions when raising the sail.

Suggest you go to the chandlery/store section of this website and get a copy of Don Guilletes "Sail Trim users Guide" .... a decent elementary guide to sail trim for novices.

 

[LANCE ON CLOUD NINE]

Thanks so much RichH - For the gift of your time invested in your great posts !! I have been absorbing them for quite awhile- always makes sailing more enjoyable! Also I pass it along when I can.

 

[RichH]

Lance -
thanks for the kudos.
The important thing is to freely pass along what may be the 'kernel of advice' that makes it easier/faster/safer for someone else; something that makes the difference between being a 'good' sailor and one who only just dabbles and never experiences the absolute sheer joy and knowledge of a well found and set up boat.
Anyone who can freely pass along such info to others ..... keeps the 'sport' alive.
;-)