Upwind Sail Trim Thoughts

by Alexander "Ali" Meller, ameller@mcimail.com

This was originally written in response to Dale Phillips question posted on rec.boats.racing. I've modified it slightly (and tried to correct some of the more obvious spelling and grammar problems...;-)

Light air (0-8 knots)
Flat sails, point mode
Mast rake 25' 8" or 25' 9" (measured with mast straight, with tape measure hoisted on main halyard shackle, and halyard fastened in normal - main hoisted - location. Measure to where transom meets hull in center, go over transom bar or transom). Launcher boats apparently go with 25' 8", while bag boats sometimes try 25' 9". Note that rake is always measured with the mast straight, or as straight as you can get it (use ram). You do not sail with the mast straight, but you measure rake with the mast straight (even a little bend changes the rake measurement considerably).

Shroud tension low - under 200 lbs (I should point out that some other people use high rig tension to flatten the upper main. I like to keep the jib luff "soft" so it is easy to read).

Mast pre-bent to flatten sail, particularly the entry, as too much fullness forward in the main closes the slot between main and jib. I believe mast bend can be critical in these conditions. Too little bend gives you too full a main. The result is poor pointing and mediocre speed. Optimum mast bend gives you the same speed as your competitors, and a little more pointing. Too much bend, may also result in poor pointing. Eyeball how much mast bend competitors with the same type of sails are using before the race. Tune up with someone before the race, and experiment with mast bend.

Vang to control the leech of the main. The top leech telltale on the main should fly some, but not all of the time (maybe about half the time). The flatter the water (less wave or chop), the flatter you can go on sail shape, and the higher you can point. Main on centerline. When the wind is ridiculously light, ease everything and just try to keep the boat moving. In very light, the weight of the boom closes the leech of the main. Don't add any vang or mainsheet tension to make it worse.

Sheet the jib reasonably close, but not so as to close the slot. I put a jib leech telltale where I can see it through the upper main window. I never stall that telltale unless I'm desperately trying to claw up from a boat on my lee bow. If you have flattened the main entry, you can sheet the jib tighter than otherwise.

Sail heeled a little and high (inside telltales lifting some of the time) in the lulls, and flat and not as high in the puffs. Pay attention to the leeches of both sails. In any decent puff, you may wish to sheet the jib half an inch or so tighter, and put a little more leech tension on the main using either vang or mainsheet. Ease jib and vang as soon as the puff dies. Crew sits inside as far forward as possible, skipper as far forward as possible (against shroud); use a telescoping tiller extension so you can sit further forward.

Medium air
Starting to power up all the way to full power, fuller sails, still pointing
Rake at 25' 8", tighten shrouds somewhat

Once the breeze comes up so that you are close to using the trapeze (assuming typical crew weight), you can power the boat up by straightening the mast, and using rig tension (250-550 on shrouds) to keep the jib luff from sagging to much (that hurts pointing). You power the boat up earlier if you are being slowed by waves or chop, later if you are in very flat water. If anyone has a crew on the wire and skipper sitting on the side tank, you should be moving to the power settings rather than the light air point settings. Inner telltales fly up (pointing too high) rather less than half the time (when you're pointing up gently to make sure you're on the wind). Keep pointing high though, as you give away more height than you gain back in speed when you foot.

Mast bend is critical in these conditions. Too much, and you do not point. Too little, and you are underpowered and also not pointing.

Sheet jib to same place as light air, use vang to keep main leech from twisting too much. The jib leech may have to be a little more open to accommodate the fuller main entry. Main on centerline. Hike hard in puffs to keep boat flat.

More air, planing upwind, (12-16 knots, depending on crew weight).
Starting to be overpowered, need to depower
Depower by raking (ease forestay and tighten shrouds) and increasing rig tension or by increasing rig tension and easing the ram to allow the mast to bend. If you cannot rake, move your jib leads aft. These changes are all gradual as the wind comes up. Pull increasingly hard on the cunningham as the wind comes up. Tighten the outhaul. You do much of this by feel. If the boat doesn't feel "in the groove" you should depower a little more, while if the boat is easy to sail, but is not pointing relative to other 505s, you may have depowered too much. Keep vanging harder to control the leech and bend the mast.

More wind! 20 knots plus (now we're starting to have some fun!)
Serious depowering required
More rake (25' 2" to 25' 6"), more rig tension (if your boat will take it you can carry over 700 pounds on the shrouds). Allow more mast bend. If you are raking, you don't need to move jib leads aft. If you are not raking, move them well aft. Pull very hard on the cunningham. Outhaul to boom band. Pull very hard on the vang. Raise the board a little to stop it gybing, and to rake it back just a little. Play the main and steer (a little) to keep the boat going upwind. Keep the boat planing - if you hit a wave, ease the main and foot very slightly. Keep jib on hard unless threatened by capsize. If the main is fully flogging, and the top is still pulling (you are trying to push on the mainsheet), you have not depowered enough, more rake and maybe more bend are necessary. You want to keep working the boat and playing the main, so that you are flat and planing fast. Crew and skipper slide aft in boat a little.

Extreme: 25-35 knots. Oh, boy! Life is good
Maximum depower necessary
Max rake (24' 11" - 25' 2"). The limiting factor is can you both get under the boom on the tacks. Radical mast bend. Board up more. All the cunningham you can get on. Lots of vang (main will twist no matter what you do). All the rig tension you dare. Play main (you are probably ragging most of it) and keep the boat "on its feet" and planing very fast upwind. Jib leads aft more. Move crew and skipper aft about a foot or more. Try to keep boat reasonably flat.

Remember to ease the vang and get the board up BEFORE you try to bear off around the windward mark.

Some General Thoughts

What you focus on, and what you do while steering the boat upwind depends on the circumstances. In shifty conditions, looking around and spotting shifts and puffs is going to be more important than trying to get the main leech to be perfect all the time. When you are able to focus on upwind boat speed, keep these in mind:
Last updated April 20, 1995