baggy mainsail

smeaks

smeaks

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i have a problem with a bag in the belly of my mainsail. when hardening up on the wind the sail just inboard of the lough is a little baggy and slack. the result is that the drive from the sail is toward the leech and when hardened up this appears to be an ineffective driver.

I have tried halyard tension, out haul tension, more kicker but cant get rid of it. It is an oldish sail but otherwise in good nick.

any ideas what could be causing this? if it is stretched can a sailmaker do anything?
 
There should be more belly in the sail towards the luff. When sailing to windward, does the luff of your sail lift and flap about? You might simply be oversheeting your headsail. Try easing the sheet a bit, or pull the genoa car aft a little to let the headsail's leach move away from the mainsail a bit. To flatten the sail using the haliard and outhaul you have to get some real tension on!

Cheers! Neil
 
When sailing upwind you could also try moving the mainsheet traveller well to windward, bringing the end of the boom more to the centreline of the boat; possibly even past this point if really beating hard.
 
As Neil says its hard to flatten the sail using the halyard - a cunningham works much better by pulling the luff foot down. Alternatively when you hoist the sail take all tension off the mainsheet & kicker, ease the outhaul & possibly even raise the boom with the topping lift and get the halyard as tight as poss.

Outhauls usually work OK as long as they have enough purchase on them - ie a winch.
 
When you've tightened the halyard as much as you can is the luff tight? On some boats you can't haul the sail up enough to get sufficient luff tension.

A racing boat would have a cunningham attached just above the tack to allow luff tension to be adjusted from the bottom of the sail. If you don't have one you could rig up a temporary on with a few blocks to see if that solves the problem.

I also agree with the first reply - if the main is actually back-winding, and is reasonably trimmed, the first thing to look at is the genny trim.
 
No one has mentioned mast bend. If it is a mast head rig then this is a bit diificult but get the inner forestay as tight as possible then crank on the backstay assuming it is adjustable to get perhaps 2 inches of middle forward.

if it is a fractional rig theya re usually more bendy by cranking on the backstay to get 3 or 4 inches of middle forward.

The mast bend pulls the excess cloth forward out of the sail so flattening it.

Some sails have a flattening reef which is a bit like a cunningham eye but is at the leach about 8 inches above the clew. This is pulled down to the boom to dispose of just a little sail area in a reef but ijn doing so it flattens the sail a fair bit. You of course also pull down the cunningham so together making a tiny reef. Try it if you have one.

In the end though a sail usually shows its age by going baggy. A new mainsail might be in order if you can't fix it with all the sugestions. good luck olewill
 
Maybe te problem is in the luff rope. As some synthetic ropes age they shrink. That has the same effect as insufficient halliard tension in a new sail. If so, it can easily be fixed by splicing additional rope in at the head - although probably a sail maker's job.
 
I'm with Will on this.
I got a new main for my boat and had the same fullness behind the luff. A bit of mast tuning sorted it out. A cunningham was also a useful addition. Nothing fancy a few blocks and some line.
On the other hand if it's just a tired sail it's new main time.
 
thanks all... a lot to consider there... also I have recently pulled up the back stay but never touched the baby... I cant wait till the weekend to have a general tweak!
 
How old and how much use has your sail had?

It could be just knackered and no amount of string pulling is going to make any difference. Dacron will remain a triangle for ever long after the effective shape has gone.

Take some photos, ideally from under the boom looking aloft on the windward side and chat to your local sailmaker; who is often offering discounts at this time of year.
 
done just that! th sail will be at the doctors over winter and hopefully come next season I will give the odd contessa a run for its money!
 
You will get all the trimming answers and luff stuff from others - so I will reply in relation to sailmakers etc.

Most sails as they age will stretch and belly is first to show. A sailmaker can cut and restitch a sail to flattewn it - but usually it's a short-lived solution.
Another idea is to have eye's fitted into sail just up from foot - with small ties through. When you need to flatten sail you use these to pull belly of sail down ... then tieing of outer ties to sort out foot. If like my sail you have reeflines in eye's at levels in the mainsail - the bottom ones can be used if necessary.

Just couple of thoughts ...
 
smeaks said:
i have a problem with a bag in the belly of my mainsail. when hardening up on the wind the sail just inboard of the lough is a little baggy and slack. the result is that the drive from the sail is toward the leech and when hardened up this appears to be an ineffective driver.

I have tried halyard tension, out haul tension, more kicker but cant get rid of it. It is an oldish sail but otherwise in good nick.

any ideas what could be causing this? if it is stretched can a sailmaker do anything?
Click to expand...
When on the wind, if your luff is tensioned and your boom strapped down, the sail should lie pretty flat. If it billows, you will experience a tendency to drop off to leeward instead of holding a close hauled course. A new sail will be capable of holding a much flatter profile when tensioned. If billowing is a problem you need a new sail; you could get your recut, but see what a sailmaker says. BTW. we all regret having to retire our sails when they are solid and no stitches missing - it's the fatigue in the material that causes loss of performance when heading.

Of course a fuller sail, shaped by age, will do perfectly on all other points of the wind, so it's a question of what kind of sailing you do, and how fastidious you are in maximising sail angle.

PWG
 
peter gibbs said:
Of course a fuller sail, shaped by age, will do perfectly on all other points of the wind, so it's a question of what kind of sailing you do, and how fastidious you are in maximising sail angle.

PWG
Click to expand...
It all comes down to money in the end. I retired my last main after about twelve hard years. Judging by the performance improvement, I should have done so years before, but I like to keep some cash in hand for food.

I could get the luff of my main to fill a week or two ago during a rather lazy sail in about 15kn true, but only later remembered that I hadn't tensioned the backstay. The next time I gave it eight turns and the sail set perfectly, on our 19/20 rig.
 
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