3 Tips for Better Boat Speed
Missing boat speed can often be found with a quick check of three main areas: rig tune, genoa trim, and mainsail trim. When I get on a new boat the first thing I always do is look at how the mast is setup before we even leave the dock. Check to see how much rake there is, how much pre-bend there is, and that the mast is straight side to side.
Tip 1: While your still at the dock pull a steel tape measure to the top of your mast and measure down to the deck on each side abeam of the mast. If the measurements aren't the same on each side adjust your upper shrouds as needed to center the top of the mast in the boat.
Now go out sailing hard on the wind in medium air and sight up the mast to see that it stays straight from side to side. If the middle sags to leeward you will need to tighten your lower shroud slightly to pull the middle of the mast back up to weather. If the top sags off to leeward your upper shrouds are too loose and need to be tightened. NOTE: Since you have already adjusted your upper shrouds to be sure the top of the mast is in the middle you should make all future adjustments equally to both upper shrouds so that the top stays centered.
If the upper shrouds are too loose tighten the upper shroud on the leeward side two turns. Always adjust the leeward shroud because there will be little or no tension on it. Now tack over to the other board. If the the lower shroud was too loose tighten it up 1 or 2 turns. If the upper shrouds were too loose adjust the leeward upper with the same number of turns you took on the other side before tracking. Now sight up the mast on this tack and see what the mast does. You will need to continue tacking back and forth, sighting up the mast each time and making adjustments on the leeward shrouds until the mast stays straight side to side on both tacks.
Tip 2: Set your genoa leads in their proper position. A good sail will have been designed to fit around the rig on your specific boat. That means in medium air when you sheet it in it should set correctly when the distance the leech is off the upper spreader is the same as the distance the foot of the sail is away from the chainplate at the deck. Generally in medium air when the boat is not at all over powered this will be with the sail 2" to 4" away from both the spreader and the chainplate (more for choppy conditions, less for flat water). This will be your base setting.
In lighter air or bumpy conditions you want to make the sail fuller for more power; mover the jib lead forward a little bit so that when the leech is 2" to 4" off the spreader the foot will be 4" to 8" off the chainplate. This makes the sail fuller and gives you more power. If you are overpowered move the lead aft so that when the sail is sheeted in tight enough to have the foot right up against the chainplate the leech is 6" to 8" off the spreader. This will flatten the sail and at the same time let the leech twist open to further reduce power.
Tip 3: Trim your mainsail. For sailing upwind when not overpowered start by setting your traveler 6" to 8" to weather of the centerline then adjust you mainsheet so that the back half of the top batten is pointing straight back, parallel to the centerline of the boat. Now re-adjust your traveler so that the boom is right on centerline. At this point you may need to slightly adjust the mainsheet tension to keep the top batten twisted open in the parallel to centerline position.
Watch the tell tales on the leech at the top two battens. In medium air of 8 to 10 knots of wind the telltale on the second batten should be streaming back almost all the time, the telltale on the top batten should be streaming aft 65% to 75% of the time. If you can't achieve this while the boom is on centerline and the back half of the top batten is parallel to the centerline your main is either too full or too flat. If the top telltale is stalled more of the time then you main is too full so try to flatten it out with a little more backstay tension to bend the mast. If the top telltale streams all the time add just a touch more mainsheet to reduce twist a small amount or ease the backstay a little to make the main a little fuller.