North Sails - Comet Tuning Guide

MAST BUTT PLACEMENT: The position of the mast measured from the aft edge of the mast to the middle of the centerboard pin should be between 20 1/4" and 21 1/4".

MAST RAKE: To measure the mast rake on the Comet, hoist a tape measure on the main halyard to the top of the mast and measure the distance to the intersection of the transom and the back deck. With the jib up and the rig properly tensioned, the measurement should be 21' 9" to 22' O".

RIG TENSION: We have found that the Comet performs best in moderate to heavy winds with the rig set up very tight. Basically, when sailing upwind in a 10 to 12 mph breeze the leeward shroud should just remain snug. Only when it's blowing over 12 mph should the leeward shroud begin to go slack. In light winds it can be advantageous to ease off the jib halyard tension thereby lessening the rig tension so that the mast rake measurement measured to the intersection of the transom and the back deck would lessen by 1 1/2".

MAST BEND: Proper mast bend is important to the Comet in order to achieve proper mainsail shape. Use your boomvang, your mast ram, spreaders, and rig tension to set the mast properly. Proper spreader length is 17" to 18". A final check to verify spreader length is to sight up the back of the mast when sailing upwind in an 8 to 10 mph breeze. If the mast is sagging to leeward at the spreaders, the spreaders are too long. If the mast is bowing to weather, the spreaders are too short. The tip to tip spacing or the "cant" of your spreaders is based on mainsail shape in medium to heavy winds. In winds above 12 mph it is important that your main is showing overbend wrinkles (called "speed wrinkles") which will run diagonally from the spreaders towards the end of the boom. These are an indication that the mast is reaching maximum bend for your main. If these wrinkles do not appear, check that your mast ram is uncleated and/or cant your spreaders farther aft until these wrinkles just begin to appear, If the speed wrinkles are higher than the spreaders it may mean that you need to block your spreaders farther out so the tip to tip measurement is greater and you mast is therefore stiffer. When your rig is tensioned properly at the dock with the jib up, your mast should prebend positive approximately 1 1/2". In light winds it may be helpful to use the mast ram to push the mast forward another 1/4" to induce slightly more prebend, flattening out the entry of the main and opening up the upper leech. In very heavy winds when the vang is on tight, it may be necessary to restrict mast bend using the ram so that the diagonal overbend wrinkles do not become excessive. Again, the mast ram basically adjusts mast bend from the spreaders to the deck and the spreaders help adjust mast bend from the spreaders to the hounds.

JIB LEAD POSITION: Your North jib will set properly in light to medium winds with your leads positioned 71" aft of the jib luff wire position at the bow and approximately 12 1/2" off centerline. At this position the luff of your jib should break relatively evenly top to bottom as the boat is slowly luffed into the wind. As the breeze picks up and the boat becomes overpowered, move your jib leads aft (up to 2" aft in very heavy winds) so that the top of the jib will break earlier than the bottom and the jib will therefore become flatter.

SAILING ADJUSTMENTS

MAIN AND JIB CUNNINGHAM: For both the main and the jib, never pull tighter than to just remove the wrinkles. It is best to leave just a hint of horizontal wrinkles from the luff of your main and jib to be sure that you don't have it pulled too tight. On the main, wrinkles perpendicular to the luff will be evident again in the lower 1/4 to lower 1/3 of the main and on the jib the same type of wrinkles will be evident if you use a stuff luff or if you are using snaps there will be slight "crow's fee" wrinkles eminating from each snap.

OUTHAUL: Pull the outhaul to within 1/2" to 1" of the band except in very light or choppy conditions, or downwind when extra power is desired. In these conditions it is advantageous to ease the outhaul 1" to 2". When the outhaul is pulled out tightly you will notice a crease just above the boom which is normal. This crease is the extra fullness designed into the sail for power when the outhaul is eased.

JIB SHEET TRIM: Basically, it is important to develop the parallel slot between the exit of the jib and the entry of the main. With the leads set properly and the sheet trimmed in the upper batten should be angled 5 to 10 degrees away from parallel to the centerline of the boat and the lower batten should be cocked in 5 to 10 degrees. In choppy conditions or when trying to accelerate, ease the sheet on the jib slightly so that the upper batten will be a full 15 degrees off parallel to the centerline.

MAINSHEET TRIM AND TRAVELLER: The mainsheet should be pulled tight enough so that the top batten becomes parallel with the boom when looking up the sail and lining the batten and the boom parallel on a lateral plane. In light winds it is impossible to keep the upper batten from hooking slightly to weather because of the weight of the boom hanging on the leech of the sail. In these conditions we suggest easing the sheet out so that the boom is approximately over the comer of the transom and the upper batten will then become more or less aligned with the centerline of the boat. It is easy to get this guide confused with the standard guide for most other conditions where the upper batten is set parallel to the boom. In choppy conditions ease the mainsheet approximately 6" to open the upper batten slightly to or past parallel to the boom. This is a "power" gear which will allow the mast to straighten slightly and the main become fuller. In addition, as the mainsheet tension is eased the entire mast and rig will rock forward slightly and the jib luff will sag making the jib fuller also.

Picture the mainsheet as your accelerator. Your traveller should be considered a "helm balancer". Ease it down to leeward in a breeze or when the weather helm increases. Pull it back up to centeriine when the boat is underpowered or when the helm is neutral. Of course, in heavy winds the traveller will be well eased so that the boom will be at least over the comer of the transom while still maintaining the upper batten parallel to the boom position.

BOOMVANG: Downwind the vang should be trimmed tight enough to keep the upper batten parallel to the boom (just as upwind). There is a tendency to pull the vang on too tight in light winds and too loose in heavy winds. Upwind in a breeze the vang is set just tight enough to keep the upper batten parallel to the boom when the sheet is eased in the puffs. Actually, this will mean a heavy amount of boomvang tension, but this is important for maintaining proper sail shape. In addition, the boomvang will help maintain proper mast bend while keeping the upper batten parallel to the boom.