Mainsail grommets and slug webbing will be affected by high loads rather than chafe. Deformed grommets get progressively weaker and should be replaced.
Reef points on the boom are a prime trouble spot. The luff of the sail tends to wear and chafe at the reef rings and the sailcloth under the reef rings tends to be crushed by the boom when a reef is tucked in.
In general, laminated sails suffer the same maladies as Dacron sails, with one addition--delamination. All laminated sails are only as strong as the glue that holds their layers together. And while huge advances have been made in adhesives, these sails are still subject to UV degradation that can eventually cause the glue to break down. Keep a close eye out for the first signs of delamination. If the sail gets this bad, it's too far gone to save.
Hardware on the front of the mast can be just as damaging as the spreaders and shrouds. Radomes, foredeck lights and spinnaker-pole tracks will chafe against the leech during tacks and gybes. Placing metal cages over these units will minimize chafe, but the leech is still a high-stress area that should be watched closely. It's a good idea before and after the season to lay the sail flat on a floor or in the yard and examine it for any signs of wear or discoloration.
The bow pulpit is another source of chafing. Many headsails have sacrificial patches sewn into the foot of the sail to minimize damage caused by the pulpit. Keep an eye on the foot of the sail near the tack, and have the patches replaced if they start to show excessive wear or discoloration.
Furling headsails are subject to excessive strain when flown partially furled. Loads are concentrated along the upper leech and along the foot aft of the tack. Over time the cloth in these areas will stretch and deform. Deep creases show that this sail has stretched and been damaged because of excessive use while partially furled. Setting a smaller headsail in high winds will increase the lifespan of the genoa. It will also present a better shape than a parially furled headsail.
Batten pockets can be trouble areas, especially on older mainsails. Battens flex continually and stress the area around the pocket, especially the pocket ends. This batten pocket had insufficient reinforcement, which allowed the batten to chafe in the pocket under load until it finally poked through the weakened sailcloth. Look for excessive wear at the forward and aft ends of the pocket before things get this bad. Make sure your batten pockets are sufficiently reinforced and the battens are properly sized. Installing an undersized batten in a batten pocket will increase chafe dramatically.
Batten cars and slugs can be another source of chafing. Well-installed batten cars will minimize chafing along the luff but still can cause excessive wear at the sail's attachment point.
The most common sail-slide system--slugs attached to grommets on the luff with nylon webbing--is also the most prone to chafing.
A misaligned slug will increase wear dramatically. The slug on this mainsail is placed too close to the batten pocket. Under pressure the batten pushes into the mast at a bad angle and results in increased chafe. A simple solution is to locate the slug in line with or farther away from the batten pocket.
The clew is also prone to chafe. Make sure that the stitching on reinforcing patches is unbroken and the clew ring has not deformed. The broken stitching on this clew's reinforcing webbing shows signs of chafe and may need to be resewn.
Overlapping genoas will inevitably chafe on spreaders and shrouds, even if there is chafe gear (spreader boots) on the spreader ends and reinforced spreader patches on the sail. Two good ways to reduce a headsail's life expectancy are oversheeting and not releasing the sail quickly enough during a tack. This headsail was reinforced with extra cloth but still chafed against the spreader end enough to weaken the cloth; the owner attached temporary spot patches to stop the small tears that occurred. If you keep a close eye on spreader patches and repair them before they start to show excessive wear, you can limit the damage to the sail.