The Sperry Sails Tuning Guide for H 12s

Written by George Moffat

The Sperry Sails Tuning Guide for H 12s

This guide is intended primarily for those interested in racing but will contain lots of information for the more casual sailor.


Since Sperry radial cut sails have a lot less stretch than older traditional cross cut sails, the use of modern low - stretch halyards is strongly recommended. Sta-Set X has 3” stretch at the sail for jib, 1.5” for throat halyard , and 1.6” for the peak halyard. V-12 Vectran single braid has 1/3 as much stretch, and three strand dacron as supplied by Doughdish has three times the stretch of Sta-Set X. STS-12 Dyneema single braid has less than half the stretch of Sta-Set X, but is more expensive. Sizes for all halyards should be 3/16” or 5mm, the minimum that the 2008 Rules allow. Spinnaker halyards should also be 3/16” for a total saving of 60% on the windage of the 80 feet of line involved for all halyards over Doughdish-supplied three strand line. Reduction of windage translates directly into less heeling moment and better pointing.

Jib Set Up:

In ordering a new jib there are two options. One is the traditional bronze piston hanks and jackline, which allows the sail to be fully lowered for furling. The other uses web snaps instead of piston hanks for securing the jib to the stay and eliminates the jackline with its windage and finicky adjustment. If you wish to furl the sail in the traditional manner, unsnap the two lowest web straps. I prefer removing the club, rolling up the jib around it, and stowing it in the cockpit under the cover. The jib clew should be lashed to the club allowing 1 - 1.5” inches of play. This allows the pressure of the sheet to flatten the sail for windward work while allowing a fuller shape off the wind. The lace line is required by the Rules but should be dead loose. The leechline should be as loose as possible without incurring leech flutter. The excellent supplied tell-tales may have a tendency to hang up on nearby seam stitching. Use white plastic tape (hardware store) to cover such threads.

Jib Trim:

In general set up the halyard taut with no observable scalloping between jib hanks. Mark the halyard with Permanent Magic Marker for repeatability. If the wind is over 15 knots, run off on a broad reach, and you will be able to get another inch or so of tension. With all halyards, ten minutes before the start of a race re-tension them in order to get rid of stretch. When sheeting the jib use moderate tension, say 30 pounds, for windward work. After sheeting it is VITAL to push the club as far to leeward as possible. Repeat this without fail after every tack or sheet adjustment. Ideally the leech of the jib should be parallel to the centerline of the boat and upper and lower telltales should break at the same time. Mark the jib sheet when this is achieved. For racing it is much preferable to have double ended jib sheets led through deck level holes in the combing and cleated on clam cleats on the forward bulkhead. This makes it easy for the crew to adjust the jib sheets on either tack, especially at the start. Obviously the sheet will need more tension as the wind increases, but the upper and lower telltales are a good guide. For boats with the factory jib sheet set up, which cleats inaccessibly on the port coaming, a Sperry fairlead/camcleat, mounted the port oarlock socket, will allow easy jib sheet adjustment from anywhere in the boat and is strongly recommended.

Mainsail Set Up:

If your boat is pre-1985 or thereabouts, the mast hoops will have neat Nat Herreshoff-designed clips to attach the sail to the hoops. These are still available, although expensive, and thus many choose instead to lash the sail to the hoops. Make such lashing as snug as possible to get the sail closer to the mast. The throat lashing at the head of the luff should be a single light line led through the cringle, up the forward pair of holes in the gaff jaws and tied across the top of the gaff. Leave about 2” of slack between cringle and the holes. Once the sail is hoisted check that the cringle is in line with the luff of the sail and adjust the lashing accordingly. Make the peak lashing snug but not especially tight. The head of the sail will appear fairly slack, but this will be corrected once the throat halyard is hoisted. Lace the sail to the gaff snugly, using half hitches at each grommet, not a spiral lacing, which will allow too much slack. The clew of the sail is, traditionally, lashed through a hole in the end of the boom, making it very difficult to adjust. An adjustable clew outhaul is permitted in the 2008 Rules and is much preferable. A four-to-one purchase is sufficient, led to a cleat on the boom above the inboard end of the tiller. If such an outhaul is rigged be sure to rig a lashing from the clew cringle around the boom so that the clew does not rise as the outhaul is slacked. A squirt of silicone on the boom makes the lashing slide more easily. As with the gaff, use a half-hitched lace line to the boom. If the traditional end-of-boom lashing is retained, foot tension can be adjusted with a sort of horizontal Cunningham. Rig a 1/8” line from the tack through the first grommet aft on the foot and back to a cleat; tension as needed. Unfortunately the 2008 Rule outlawed the real Cunningham, used on almost all race boats, which allowed simple one-handed tensioning of the luff.

Mainsail Trim:

In hoisting the main keep the gaff only slightly above horizontal until the luff is taut. Belay the peak and sway up on the throat halyard as hard as possible (Note: in older boats be sure that the halyard jam cleats only jam on the upper end or proper tension is impossible to attain). Mark the halyard. Raise the peak until heavy wrinkles show from peak to tack. These should disappear as you start to sail. If not, ease the peak slightly. If wrinkles show from throat to clew the peak needs to be raised more. Check that the throat of the sail is smooth, with no wrinkles or puckers and modify the throat lashing as needed. If scallops appear between the mast hoops the throat halyard needs more tension, which can only be attained by dropping the peak about three feet and swaying on the throat halyard. When all seems about right mark the peak halyard. Note: if the throat halyard is really taut you will probably note a hard wrinkle from the throat on the port tack although all will be well on starboard. The cause of this odd phenomenon is that the tight throat halyard forces the gaff jaw against the mast, creating a hard line at the throat of the sail. The cure is to run the throat halyard inside the gaff jaws and then to the cleat. Sounds weird, but it works. Boats built since about 1985 have redesigned gaff jaws and may not have this problem. Since the throat halyard is the most heavily loaded line on the boat you might want to spring for 30’ of V-12 Vectran ultra low stretch line. Tie on a 15’ tail of any cheap line for hoisting .

For racing purposes replace the three-strand mainsheet with 1/4” braided line (Sta-Set X). It kinks far less and runs through the blocks more easily . Mark the mainsheet for optimum trim in a 12-knot breeze. This will only be a bench-mark as the trim is dependent on how high the gaff is peaked, but it is useful for rounding leeward marks when the crew will usually be doing the trimming, and it gives the skipper a baseline for fine tuning. Keep in mind that the main is a major steering aid. In bearing off around a mark, or ducking a starboard tacker, lead with easing the main rather than the rudder. Similarly, in tacking from reach to reach, drop the tiller and sheet in hard with both hands. The boat will come head to wind. Then use the rudder and ease the main.

Sailing to Windward:

In light airs sail the boat with 8-10 degrees of heel, moving the crew as necessary. For a bench-mark the boat is heeled about 12 degrees when the lee shroud is perpendicular to the horizon. Fore and aft the weight should be centered over the middle of the seat (see section below on weight placement). Ease the jib sheet about 1-2” from normal setting, and the halyard perhaps one inch. Check that the leech lines are as loose as possible without leech flutter.

In medium airs — ten to fifteen knots — peak the gaff up just short of inducing peak-to-tack wrinkles and sheet in the main hard, especially in smooth water. The last two or three inches of main trim really helps in pointing. Keep in mind that, due to the odd traveler arrangement in a Twelve, the main should be sheeted two or three inches tighter on the port tack. Clew outhaul should be taut-to-tight. Out haul adjustment is not very critical in a Twelve-footer as the main is cut without a shelf. Heeling more than 15 degrees is slow due to weather helm drag, and light crews should be de-powering at the upper end of this wind range.

In heavy airs — 18 knots and up — be sure the jib halyard is as tight as possible and trim leech lines to eliminate leech flutter. Drop the peak halyard a couple of inches to flatten the main and reduce heeling. Ease the mainsheet a foot or more to reduce heeling and weather helm. Head up, especially in gusts, so that the windward jib tell-tale is angled up about 45 degrees. When tacking, especially in large waves, be sure to ease the main two or three feet after the boat passes head-to-wind. Head off a bit below the new course, trimming the main as the boat picks up speed. It’s very easy to get caught in irons if you fail to do this. If caught in a really heavy squall remember the old gaff-rigger trick of scandalizing the main. Drop the peak halyard until the gaff is horizontal. This effectively halves the area of the main and much reduces heeling. Twelves also heave-to very well. Lash the jib club to leeward, tack, and lash the helm to leeward, trimming the main moderately. The boat will forereach at about half a knot. Very handy trick for eating lunch on a blowy day . . .

Off the Wind Sailing:

Modern courses are generally windward-leeward as reaching legs tend to be a parade, with passing difficult to impossible. Unlike lighter boats, Twelves, with their very high displacement-length ratios, cannot be tacked downwind effectively. The basic trick in downwind sailing is to ease the peak halyard enough to eliminate the peak-to-tack wrinkles. This will require eight to ten inches in lighter airs and little if any adjustment in 20 knots. Mark the halyard at the correct point for average conditions. Be sure you marked the halyard for the windward setting since returning to it is vital before the leeward mark. Clew outhaul adjustment is unnecessary except in light airs. When running the boat should be heeled about five degrees to windward to neutralize the helm. This will also aid in winging out the jib. When gybing in more than 12-14 knots be sure to sheet in the main so boom is 45 degrees or less off the boat’ s centerline. Failure to do so will often break the gaff jaws, especially in higher winds.

Weight Placement:

1. The center of the crew weight should be over the supporting knee of the seat.

2. If there is any sea running or motorboat wakes skipper and crew should sit as close together as possible to reduce hobby-horsing (27% of an H 12’s length is in the heavy overhangs). Togetherness is fast, but also tough on the skipper’ s arm as the tiller is a distant reach. In casual sailing skipper and crew are often seen sitting on opposite ends of the cockpit. This is comfortable but slow as it both increases hobby-horsing and reduces lateral stability due to the crew weight being closer to the boat’s centerline.

3. Unless it is blowing quite hard (18+ knots) there is little need to move much aft on the downwind legs. If the crew is light sitting to leeward and acting as a human boom vang works. In a blow keeping the boat flat is more important.

Tiller Usage:

The tiller of an H 12 has an enormous mechanical advantage (about 12:1) over the rudder, so it is easy to overuse it. The rudder is a very effective brake. Try sailing dead downwind past a mark or mooring buoy about 1½  lengths away at any speed. Jam the tiller hard over just after the stern passes the mark. After 180 degrees you will find the boat virtually stopped with the bow just at the mark. Unfortunately this stopping action works just as well for a crash tack or gybe . . . When rounding a windward or leeward mark use mainsail trim as the primary turning force with the rudder, which is much less powerful, as secondary.

Rigging List:  (Note: All halyards are Sta-Set X, 3/16”)

Jib halyard, (also spinnaker halyard) 32 feet.

Throat halyard, 38 feet

Peak halyard, 56 feet. (Add 15 feet if halyards need to be brought forward to the mast to clear boat cover.)

Main sheet: 1/4 ” Sta-set X, 45 feet.

Spinnaker Equipment List:

Spinnaker! - From Sperry Sails

Sheet & Guy - 3/16″ Sta-set X, 20′ for each

Spinnaker Pole Lift - 3/16 ” line (about 20′) with snap shackle on pole end, through a strap eye on the forward side of the second mast hoop down from the gaff, to a mini cleat, which screws to the starboard side of the mast, about gooseneck level. It’s a good idea to rig 1/8″ shock cord from hook to a strap eye at the bottom of the mast and then back up to boom level. This allows the hook to be ready for use without attaching it to anything.

Twings - One on each side of the boat, with fairleads. These are lines through which spinnaker sheet and guys pass. They lead through ½” nylon bullseye fair leads which mount on the raised rail, just behind the shroud turnbuckles. The twings are 1/8″ nylon lace line about 6′ long, and lead through ½” holes drilled through the coaming (drill pilot hole through outside coaming first). The line then cleats to mini cam cleats. A tightened windward twing prevents the pole from rising, rather like a fore-guy.

Quissett Blocks - From Sperry Sails. These are combined fair leads and cam cleats and mount in the oarlock sockets on the coming amidships. They are leads and cleats for the sheets/guys and make handling and trimming, especially gybing, much easier.

Spinnaker Pole - Can be obtained at Doughdish, LLC, or Cape Cod Shipbuilding in Wareham. The aluminum poles are much lighter and easier to maneuver.

George Moffat has been racing boats for many years — International 14s, 5-0-5s, and J-24s mainly — and has owned an H 12 for twenty years. He has raced with Sperry sails since 2006, and has been H Class Champion twice.

Beverly Yacht Club


edgartown yacht club



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