Advice Requested - Resizing Mainsail ?

[Kindle]

I would like to hear from those of you who can advise. We are purchasing a new mainsail and a sailmaker that we received a quote from has a brand new sail thats luff is a few feet too tall. He suggested that he can recut it to our exact demensions. It would be about half the price. It also has a few upgrades that we would not be getting if we order a new one. So, my question is can a mainsail be shortened several feet (6) without compromising the shape? We are not racers but still want an effecient sail. Thank you for taking the time to share your knowledge.

[s/v Beth]

Do you trust this sailmaker? I make a habit of buying dirt cheap second hand sails and make them fit my boat, but it has to be done by someone that knows what they are doing. Some sails have builds into them that this would not work, others adjust just fine. I would make sure that it doesn't hit my aftstay, that if it is a sail that goes beyond the luft line that is has battens, etc. Like most answers in life, the answer is "it depends".
If you spent all that money on a clamboat, maybe your degree of tolerance in a sail is smaller than mine...

[Kindle]

yes, we have had this sailmaker do repairs for us in the past and we were happy with the work. However, I do not know enough about sail design to understand what would be involved in shortening it by 6 feet and how that will affect the sail. I am hoping someone here would better be able to advise. I would like to save some money, but I am sure that he would like to recoup some money on this sail too. He made it for another boat and made a mistake on the measurements and had to make a whole new one for them leaving him with an extra sail sittting in his loft for a while.

[Eleven]

From my experience it's the boat trim that's affected by changes in area, or just in the pressure point of the new sail. A previous owner put a battened roach main on my boat. I now have to spill wind to get a decent balance on the rudders because the extra area is well aft moving the driving point considerably when close hauled or reaching.
When a strong gust in a calm hit my cat it weather cocked firmly to windward and that's not in the plan for a cat either. Fortunately it was in the right general direction and there were no obstructions in the way but I was out of control until the water speed built up to give rudder authority. (It took longer than the 'What the ?' took). Yet another lesson learnt - start the noisy sail and keep steerage way on.

[s/v Beth]

Kindle- all sails have an angle from the head to the boom that has to be correct for the boat. If he is just shortening it by taking the bottom out, well he should do a lot of sewing. If he was taking the head off, that will, as Eleven says, change the center of effort for the boat and may give it too much weather helm. If the angle is wrong, he will have to cut alot off the side and top- and do alot of sewing.
Don't get me wrong- I love cheap. But I would not give him a dime till I tested in in various wind conditions on my boat. If he will agree to that, maybe you have a deal.

[sestina]

As an ex sailmaker it's a quite easy job to shorten a mainsail's luff.

Lift the leach tabling and all the batten pockets.
Reshape the leach to conform to the new luff length, replace the batten pockets and leach tabling.
If necessary remake the clew patch to suit the required foot length.

What you don't do is merely cut the foot off to suit. All the shape of the sail is influenced from the tack seam upwards. After half hight the sail's pretty flat.

[s/v Beth]

If your going to do all that sestina, what advantage is it to use the old sail? Why not just make a new one that is designed for the boat? It seems like you are redoing all three sides-
As a novice sailmaker, I would really like that answer to this one.

[Intrepid]

Originally Posted by s/v Beth

If your going to do all that sestina, what advantage is it to use the old sail? Why not just make a new one that is designed for the boat? It seems like you are redoing all three sides-
As a novice sailmaker, I would really like that answer to this one.

It's still easier than building a new sail. Also, if the sailmaker can sell a sail he has lying around for whatever reason (wrong size for original customer? Non-payment from original customer?) both the loft and the OP come out ahead.