A first time yacht owner was in the chandlery late November and was complaining that he thought the mainsail he had inherited was badly stretched down the leech as the boom was not clearing the spray hood when it was hoisted up as far as it would go and if he lowered the hood and then sheeted in the sail, a severe crease ran from the clew through the inboard ends of all the batten pockets. Apart from that it was a real sod to hoist! He then started talking about buying a new main to Andy, boss man, who whilst a wizz on all things mechanical and electrical, suggested to him that perhaps once the old git (ie. me) was up and running again after his replacement hip that he brought the offending sail into the loft for evaluation. Well I am back on my feet, even more grumpy if thats possible and here's what I found. Sail was still in fairly good condition for its age, cloth had a bit of 'body' however the bolt rope had shrunk which meant that once it had been cut in the tack area and then the hand stitching at the cunningham hole/reef points unpicked and stretched out, the bolt rope shot up the luff tabling 17cm, which should mean the sail could be hoisted higher up the mast allowing it to clear the hood. The sail slides looked as though they had been lubricated with wheel bearing or stuffing box grease and apart from staining the sail, me-thinks the lubricating properties of this gunge would be zilch! To remove the grease I used the excellent 3m citrus cleaner and we then sent the sail to Hancocks sail laundry for a thorough clean.
As for the severe crease down the inboard end it would be hard to tell by laying out the sail on the loft floor what the problem was but I think that by putting the battens in the wrong way round ie stiff end first flexible end at the leech, the previous owner wasn't doing the sail any favours!
Sail slides are always going to be a source of friction, worse still if the main has been constructed with a full length top or top and second batten. As a sensible alternative to grease I can strongly recommend carrying a can of Mclube or Smooth Sail on board. A regular squirt of either will help make hoisting the main an awful lot easier.