North Sails Southwest C22 Tuning Guide

By North Sails One Design
Comments By Pete Harper
#1110, Hummingbird
Added notes by Jim Deeter

Note: The original tuning guide was provided by Ullman Sails in Dallas. They have since been sold and are North Sails Southwest. My comments are shown with "[ ]".

These adjustments are intended as a guide. They may vary due to crew weight, wave conditions, fixed or swing keel, spade or kick-up rudder, and individual sailing technique.

Tuning at the Dock

Tools Required - 50 foot tape measure, Model A Loos tension gauge, and tools to adjust turnbuckles.

Mast Rake - Measure the distance between the top nicro-press of the jib halyard and the pin of the halyard shackle attached to it. Attach the tape measure to the jib halyard shackle and pull the halyard up until the nicro-press fitting jams in the mast head sheave. The distance to the aft hole of the forestay tang at the bow should be 27 feet (adding in the first measurement) with the backstay pulled taut.

[I use a separate measurement that is very similar to Ullman’s. I measure from the main halyard jammed at the top to the transom cut out for the tiller. The distance should be 29’ 2 ½". If you set your boat up this way the first thing you will notice is the mast is swept way back. I’ve played around a little with mast rake. The further I moved the mast rake back the better the boat pointed with no apparent loss in boat speed. Be aware that moving the mast back increases weather helm.]

I find that using Pete's backstay measurement works best. To start, remove the boom and loosen up both forward and aft lowers. Especially, the forward lowers. Loosen them up as far as safe initially. Get your backstay measurement and then proceed with Mast Tuning. Measure backstay length to the back edge of the cutout on the rear transom.

Mast Tuning - Tension the forward lowers and the aft lowers so that the mast remains straight for and aft and in column side ways until all four read 24 on the tension gauge.

Tension the upper shrouds to read 28 on the tension gauge, again checking to see that the mast remains in column sideways.

[I set my shrouds up a little differently because I don’t have a tension gauge. First I use the tape measure to make sure the mast is straight side to side. Measure from the mast head to the toe rail at a fixed place on each side. Tension the uppers so that they are sorta taut. Sorry no tension gauge.]

I prefer using the Loos gauge to measure tension. If you find that the rear lowers are too long at this point consider exchanging the forward lowers with the aft lowers. If this still doesn't work you will have to replace the aft lowers to obtain the correct tension.

[I use the forward lowers to control mast pre-bend. With the old tight leeched North main I have, I like about 1 ½ inches of pre-bend at the spreaders. You will want to adjust this to match your sails, see disclaimer above. To measure pre-bend I use the main halyard. Hold the main halyard taut against the mast at the bottom mast band. Sight up the mast to the spreaders, pre-bend is measured between the main halyard and the back of the mast at the spreaders. Tension the aft lowers to support the mast. You don’t want the mast to be able to pump fore and aft, this is a good way to loose a mast.]

Tuning Under Sail

When sailing, check the tune in different wind ranges. In light air (0-7 knots) the forestay should be allowed to sag six to eight inches with the backstay eased completely. In medium air (8-15) the backstay should be applied to reduce the sag to three to four inches.

Check in all winds to see that the mast stays in column sideways and make the minor adjustments necessary. In heavier air (15+) the top of the mast may fall to leeward due to shroud stretch and hull distortion. Efforts to compensate too much for this might lead to damage without significant speed improvements.

[If you look at some of the Dallas/Fort Worth boats, they have reinforced the shroud connections to the deck. Some even have cable tie downs for the forward and aft lowers to reduce bending of the deck. I checked with the National Measurer and this is OK by class rules. I glassed in my bulkheads to reduce deck movement. I would highly recommend you make this modification if you are going to aggressively push your boat.]

Deck Reinforcement for Lowers - This could be a significant improvement in both boat speed and pointing. Highly recommended. To minimize shroud flex due to deck flexing it is advisable to reinforce the forward and aft lowers at the deck. One way to accomplish this is to run supports from the bottom of the shroud bolts to the bulkhead. Both forward and aft supports are fastened through the bulkhead. Click here to view an example of forward and aft support brackets as installed on We Deliver.

Forward Aft

Sail Trim

Light Air (0-7 knots)

The mainsail traveler should be pulled to windward with the sheet eased so that the boom is on the centerline and the second batten from the top is parallel to the boom. The cunningham should be eased so that horizontal wrinkles (speed wrinkles) begin to appear along the luff of the main and the outhaul eased so that the shelf foot fills out.

[I have telltales on the top two batten aft tips. With the traveler to windward and no boom vang; sheet the main until the telltales start to curl; ease the sheet back out until they just fly again. Over sheeting the main is the biggest problem I see with mainsail trim in light air. If the leech is too tight you are just putting on the brakes. You will see a fair amount of mainsail backwind with this setup don’t worry about it. I would also carry more outhaul than they recommend. Watching David Hayslip at the ‘94 Texas Spinnaker States, I noticed that he had a very tight outhaul even in light air. I talked to him later and he said that most mainsails are cut too full for the C22. A full mainsail closes off the slot between the mainsail and genoa.]

The genoa lead should be set approximately 30 inches forward of the deck drain and inboard tracks should be installed if possible. The genoa should be sheeted so that the foot at the midpoint is directly over the edge of the deck and the leech is four to six inches off the spreader tip. The halyard should be tensioned just enough to remove the horizontal wrinkle along the luff and the backstay eased to allow six inches of headstay sag. If you have two sets of snaps along the luff, the forward ones should be used.

Medium Air (8-15)

Ease the traveler to avoid excessive heel. Use the mainsheet to adjust the leech of the main, keeping the second batten parallel. The outhaul should be adjusted for the amount of power needed (pull until the shelf foot folds on the boom if overpowered). Adjust the cunningham to remove all horizontal wrinkles along the luff.

[I generally center the traveler and use the boom vang to adjust leach tension. Don’t use too much vang in the lower wind ranges. Increase vang tension as the wind builds. Again I use the telltales to control mainsail trim (keep them flying), unless I’m over powered. The backstay tension is increased to control the headstay sag at about six inches, less in the upper wind ranges. Adjust the cunningham to keep the draft at about 50% of the mainsail.]

The genoa lead should be moved aft as the wind increases, as much as four inches from the light air settings and sheeted two to three inches from the tip of the spreader. The amount to move the lead will vary depending on the power needed for waves and crew weight. The backstay should be tensioned to remove as much headstay sag as possible without depowering the boat too much.

[Moving the lead position doesn’t seem to work as well with the new Mylar sails. If you think about it when you reduce the amount of headstay sag you are moving the luff forward. This is effectively the same as moving the leads aft. I don’t move the leads at all until the wind gets to 20+ and we have to depower.]

Heavy Air (15+)

Ease the traveler all the way and adjust the boom vang to control leech tension. The mainsheet can then be used to move the boom in and out to control heel (i.e. vang sheeting). Adjust the cunningham to remove all wrinkles along the luff and pull the outhaul so that the shelf foot is folded tightly along the boom. Tensioning the backstay will open the leach and depower the rig as well as giving additional headstay tension.

Now is when you want to depower the main. In these conditions the mainsail mostly helps for balance and heel control. Time for the flattening reef if you have one. This will help depower the mainsail. Use the vang to control leech tension when you dump the mainsail. The cunningham should be very tight. Play the mainsheet in and out to control the heel of the boat. Don’t be afraid to completely luff the sail in the puffs. Don’t let the boat roll up as you will only side sideways.

When racing without a spinnaker, the genoa should be carried as long as possible upwind so as not to sacrifice offwind speed. Moving the lead aft and outboard will keep the slot between the main and genoa open. Don’t be afraid to pinch the boat (sail the genoa slightly luffing) to avoid excessive heel.

[I keep the genoa up as long as possible. The C22 naturally has a tremendous amount of weather helm. Keeping the genoa up keeps the power forward in the boat and helps reduce the helm. I would put the first reef in before I switched down to the jib. Keep the boat as flat a possible; everyone on the rail including the skipper; constantly play the mainsail in and out, and pinch in the puffs. Hold on, this is when it gets fun.]

Sails

Class Jib - Sheet hard enough so the middle of the leech is pointing aft, top of leech is twisted open, and bottom leech is hooked to weather.

Spinnaker - The best indicator for adjusting pole height is to keep the clews level. This will mean keeping it low in light air and raising it as the wind increases. When broad reaching and running, set the guy so that the pole is perpendicular to the wind and continually ease the sheet so that the luff curls slightly. Remember that over-trimming can slow the boat radically.

The genoa should be dropped when using the spinnaker, but the class jib may remain up when reaching.

[Kevlar or Spectra sheets are the only way to go for spinnaker sheets. Once you trim the pole there is no stretch. Even on a tight reach in a good blow the pole doesn’t wrap around the forestay. In heavy air, Marilyn Boemer taught me a trick. When reaching, leave the jib up with the spinnaker. This way when you get knocked down or broach and you have to luff the spinnaker to get control over the boat, the jib will help keep the bow from rounding up into the wind. I have also used this effectively to drive over boats on a reach. The other boat tried to luff me up and both our spinnakers collapsed. With the genoa up we have enough sail to drive over them. When broad reaching in 15+, we have found it effective to leave the genoa up with the spinnaker. The added sail area has allowed us to break up on a plane when other boats were not able to.]