Bookmark and Share Email this page Email Print this page Print

Storm sails

Jan 1, 2003

How can you tell if a storm trysail is the right size? Easy, hoist it up at the dock on a calm day. Leave it up for a few minutes. If it appears ludicrously small, if passers-by on the dock snicker as they walk by, then it's the right size.

This test, unfortunately, is of little practical value, since by then the well-intentioned boat owner will have already spent the $1,000 or so that might be necessary to construct his bulletproof storm trysail. By way of further testing, the skipper might next hoist up his just-out-of-the-sailbag storm jib or storm staysail. How will the dockside kibitzers react to that one? More snickers to be sure.

It's true that storm sails do look ridiculously small when viewed from the perspective of a calm day at the yacht club. Even an experienced ocean sailorone who knows the awesome force of wind and sea that can be encountered offshoremight feel silly hoisting up those tiny scraps of rigid sail cloth on a Sunday afternoon at home. The storm trysail especially, with its inefficient-looking, elongated shape, can appear downright silly when hoisted at the dock. Tough, stiff, and little used, these storm sails only begin to appear logical when the wind gets up. When far offshore on a howling night, a well-set trysail and storm jib really earn their keep.

Storm sails are meant to be tiny, indestructible, and simplistically rigged. They don't take up much space when stowed. They require little in the way of maintenance. And, in theory, they are easy to rig and set. Properly equipped, a boat will be able to carry both a storm trysail, to be set on its mainmast, as well as a storm staysail or jib to be set in a complimentary way just forward of the mainmast. In different situations, however, a boat might spend time under either trysail or staysail alone. Skippers of ketch-rigged sailboats sometimes have storm sail strategies unique to that rig, but a storm trysail can and should still be flown effectively from the mainmast when the time is right.

There are a number of rigging factors that must be considered when designing a storm sail. In general, a storm trysail should be about 25% to 30% of the area of the full mainsail, according to most sailmakers. More sophisticated formulas are available in the literature, but they usually end up with a similarly sized sail. One is 0.05 times the square of the full mainsail luff. Another is 17.5% of the mainsail's luff times foot, which works out to just under 35% of sail area. Ideally, the storm trysail should be a bit smaller than a triple-reefed main. The triple-reefed main has never been very popular. In older days of heavy wooden booms, a triple reef would leave what's left of the sail sometimes supporting the full weight of boom (despite the use of topping lifts and quarter lifts). And, in modern times, with high-tech sails, the distortions and stresses imposed by this deep reef can make both owner and sailmaker uncomfortable. Thus, when conditions become too much for a double-reefed main, and a skipper wants to hold position by heaving-to or wants to work to windward, it may be time for the storm trysail. Unless, of course, the captain chooses to run off on a broad reach before the wind, in which case a storm jib or storm staysail flying alone might be all that's needed.

A trysail should not be built too small, sailmakers say, because the smaller it is the less useful it will be, except in the most extreme weather conditions. A small trysailsay, less than 25% of mainsail areais less useful as a replacement main and also less useful for actually moving the boat in heavy but not necessarily perilous conditions. Trysail design criteria

The actual dimensions of a trysail are, like those of all sails, restricted by several design criteria. The trysail tack should, when fully hoisted, be positioned just above the bulk of furled mainsail. A mainsail normally cannot be removed from the boom without considerable effort, and the trysail is almost always set with the mainsail furled and well lashed in place. By way of the tack, there should be a heavy rope tack pennant (rope so as to be adjustable and flexible as to point of attachment).

The trysail clew and overall shape of the sail should trend down and aft toward the existing or designed sheeting point. The clew should not extend too far below the boom, if at all, since the trysail often needs to be shifted to the other side while hoisted, and yet it should be easily reachable from a standing position on deck. In some situations the boom end should be lowered and secured to the deck, thus rendering it well clear of the trysail clew.

The trysail head should ideally rise as high as the lower spreaders, or close to the point where forward lower shrouds/stays attach to the mast. To the extent that forces exerted by the trysail head are balanced by forces of shrouds, stays, and possibly a storm headsail, a boat's mast should be happier in riding out the tempest this way. Factoring in these considerations, plus striving for a pre-determined sail area, one will inevitably end up with a very odd-looking sail. "This is the only sail in the universe where the luff is shorter than the L.P. (least perpendicular), so it's a very awkward triangle," said Dave Flynn from Quantum Sails' Annapolis, Md., loft.

Sailmakers differ on a number of other design considerations, but there is a consensus that a storm trysail should be attached at the mast by an independent track that begins not far off the deck and, ideally, runs the full height of the sail's luff. A traditional alternative has been to have the trysail track intersect with the mainsail track somewhere above the height of the furled main, but mainsails and masts come in so many different shapes, sizes, and technologies today that a full-height independent track often is simplest. Without some kind of independent track, a storm trysail is much less likely to be used and would be considerably more difficult to set and hoist, especially during rising wind conditions. A storm trysail track, either to port or starboard of the mainsail track, should rise a foot or two above where the head of the sail is intended to be, thus providing flexibility as to hoist and tack position, and providing more support, through regular fastenings, for the track where the head of the sail begins. As with a mainsail track, the bottom of the trysail track needs to have a fitting to prevent slides from falling off when the sail is not hoistedthis is especially true for the storm trysail which can be thus attached to the mast and put in place before it is actually needed in deteriorating weather conditions. (The trysail can be attached to the mast and secured in a bag on deck at the outset of a voyage.)

As for a halyard, the storm trysail sometimes ends up sharing the main halyard with the mainsail, especially on boats being retrofitted. This is not necessarily problematic, except that detachment of the main halyard (sometimes affixed with wired or moused shackles) can be an exertion in rolling or pitching sea conditions, especially if it is not reachable from deck, requiring a crewmember to straddle the forward end of the boom to reach it. Mast builders say that for a new boat a dedicated storm trysail halyard can be installed at the mast not too far above the head of the trysail track. Such a halyard, in addition to the advantage of its availability, also can provide a degree of inward pull on the head of the sail, thus reducing strain on the track.

Sailmakers differ on the advantages of a single-ply storm trysail or double-ply. One might prefer to construct such a sail out of two layers of five- to seven-ounce material, sewn carefully together, while another might recommend a single layer of 10- or 12-ounce material. A two-ply sail of lighter material might be more flexible and less susceptible to damage from chafe or snagging, while a single-ply sail is less complex in construction and possibly easier to repair or patch on board.Panel design

Similarly, sailmakers may differ on the ideal design of a trysail. Some advocate a miter-cut sail, with panels of material running perpendicular to leach and foot and meeting at a miter seam; a scotch cut, with panels running parallel to leach and foot and converging at the miter seam; a vertical cut, with panels running parallel to the foot; or a radial cut, with all seams radiating out from the clew. Everyone agrees, however, that a trysail's corners and edges must be very heavily built with oversized, reinforced cringles and adequate protection against chafe and destructive flogging, plus double or triple layering of tape along edges. Most would probably opt for a bolt rope inside the luff tape as well. Similarly, it goes without saying that sail slides should be attached in as stout a manner as possible with minimal distance between slides and attachments made with heavy pieces of sewn-in-place webbing. (Some sailmakers recommend additional grommets along the luff for possible use in lacing the sail to a mast in the event of difficulty with or damage to sail slides or mast tracks.)

Sailmakers generally agree that most storm sails are expensive. Construction of a finished storm trysail will cost in the neighborhood of $10 per square foot or more, depending on the complexity of the sail and the amount of hand-stitching. While the checkbook is out, however, yacht owners might also have to cover the cost of additional tracks on the mast, additional provisions for sheeting on deck, and for additional costs of rope, blocks, and other gear required to get the sail in place and working. Offshore security in the form of storm sails doesn't come cheap.

Everything on a boat requires careful consideration, and this is no less true with the question of how to handle sheeting of a storm trysail. At its simplest, the trysail is little more than a oversize windvane, intended to provide a boat with some weathercocking force from back aft, to reduce rolling, and provide stability, maybe with a bit of forward sailing ability also thrown in, depending on the situation. Trysails are mostly flat sails, with little shape intentionally built in. Sheeting of such a sail would seemingly be a simple matter, except for the tremendous wind forces involved and for the need to occasionally shift from one tack to another.Sheeting angle important

Of primary concern is that the sheet be led to its deck fitting at the proper sheeting angle for the sail. Trysails are designed and built for one sheeting angle to handle all that force, and deck fittings must be designed or retrofitted to match. They probably will be somewhere aft of or near the end of the boom, depending on design, and not too far off the centerline. Needless to say, they also must be strong enough. Rope used for sheets should be extremely robust and kept free from chafe. Trysail sheets should be kept permanently attached to the sail's clew and stored in the same bag. It is best if the sheets are of three-stranded rope and permanently spliced in place, since knots can come apart under force of flogging. There could even be an argument for double sheets on each side, since the loss of a trysail sheet (or loss of control) in heavy wind could be calamitous. The sheets may need to be led to a winch or tightened with a block and tackle, but some sailors adopt a practice of attaching the sheets before the sail is finally hoisted home, thus allowing the halyard to do most of the sheet tightening. Nevertheless, in the event of tacking or gybing, the alternate sheet may need to be tightened with appropriate leverage. Of primary consideration is keeping the trysail clew under control since flogging during maneuvers can be dangerous and destructive. Sheeting arrangements should be planned out in advance and rehearsed, remembering that the sail is just as likely to be needed in darkness as in daylight. Once the sail is properly set, halyard, tack line and sheets can be permanently marked with sewn-in whippings to facilitate set-up next time.

The storm trysail is not just for globe-girdling circumnavigators or those planning to sail the Southern Ocean. The reality is that a boat cannot be described as being prepared for offshore sailing without one. Although the sail has a variety of strategic uses, its primary function is to get a boat and its crew through a short stretch of dangerous weather in a safe and seamanlike manner. There are times when it will be the most valuable sail onboard.