Selecting the right sail for racing

Guy Waddilove looks at the vast variety of sails available for modern racing, whether on an IRC superboat or a performance cruiser.

The huge wardrobe of sails flown aboard square-riggers is littered with obscure and confusing names like lower topgallants, royals and moonrakers, but the inventory of sails aboard a modern race boat is not much better. Selecting the most suitable sail or combination of sails for the conditions is vital to success on the water, and with a wardrobe of twenty plus sails on board some racing yachts, there is certainly plenty of room for error.

Following is an overview of the sail inventory you may find aboard a modern cruiser-racer or racing boat. The names listed are those used by Doyle Sails - different sail manufacturing companies may use slightly different terminology.

Mainsails

Mainsails are simple; inshore or offshore and built with a level of robustness to suit the conditions. An offshore mainsail will be of a heavier construction than an inshore main, with more yarn, higher denier count and more robust reinforcements. An offshore main will have either two or three reefs depending on how it is likely to be used, while an inshore main will either have one reef, or possibly no reefs at all.

A storm trysail is normally carried in offshore races, to be used in place of the mainsail in extreme conditions.

Moving forward of the mast is where the waters tend to become muddied with respect to terminology.

Strictly speaking jibs and genoas are not interchangeable terms: the jib fills the fore-triangle (the triangle formed between mast, forestay and deck) with a very slight overlap, whereas a genoa will overlap the mast considerably.

Genoa size will be given as a percentage, with the figure representing the size that the longest perpendicular of the sail (LP) is greater than that of a sail that fills the foretriangle. For example a 135% genoa will be a generous sail which measures 35% more from its clew to luff than a standard jib would.

Upwind Headsails

Upwind headsails are prefixed with the letter J followed by a number indicating size; the area of the sail decreases as the number gets higher. The letter J can be substituted with the word Code

J1 (Light med or Code 1): This sail is used close hauled in light conditions up to about 8-10 knots of breeze.

J2 (Med Heavy or Code 2): The J2 takes over from the J1 once the wind increases past about 8 knots and is good until about 14kts.

J3, J4 and J5: These are sequentially the next sails in this range and would be used at 13 knots, 18 knots and 27 knots respectively. Heavy weather jib sizes as classified in the safety book must be taken into account when working out the inventory. From about 32 knots upwards a storm jib would most probably be used.

The Jib Top (JT) is the next sail logically in the inventory. The JT is used in true wind angles greater than around 50 degrees and wind strengths between 6 and 20 knots.

Drifters are used in very light wind conditions of up to about 4 or 5 knots to keep forward motion on the boat. These sails need to be very specifically designed in terms of size and detail to make sure they work effectively.

The Genoa Staysail is a custom-designed sail used inside either the jib top or the Code 0; it can be a very effective sail under certain conditions.

 Off-the-wind sails

Racing under IRC Offshore rules, there will normally be a limit of four or five spinnakers that can be carried on board for a race depending on a boat’s IRC Certificate. A decision on inventory based on likely weather conditions has to be made before starting a race.

The spinnaker staysail or spaysail is a lightweight staysail flown with the spinnaker when broad reaching. It is loose-luffed which allows the luff to project forward and to windward to aid downwind performance.

Asymmetric spinnakers have become the norm among many classes of racing yachts, mainly because through-the-water speeds have become faster which has resulted in boats generally sailing with narrower apparent wind angles when they are sailing off the wind.

On a reach, asymmetric spinnakers perform better than symmetric spinnakers. They have a longer luff which lowers the centre of effort of the sail and a straighter leech exit profile. This allows the shape to exhaust much better, reducing sideways force and thus allowing the boat to sail faster.

The range of asymmetrical spinnakers carried aboard a yacht will cover the full range of off-the-wind angles from broad running to tight reaching. Asymmetrics are coded with an A prefix and a number.

An A1 VMG is a fuller design for better stability and performance downwind. The A1 VMG is suitable for stable, powerful boats that want to improve reaching capability. Typical wind angles would be from 85 degrees to 165 degrees apparent and a wind speed range of 5 to 15 knots

The All Purpose A2 is generally the largest sail carried onboard; it is a full-sized gennaker for sailing deep and is generally made out of light to medium spinnaker nylon. Used for wind angles 70 to 150 degrees and wind speeds of 12 to 22 knots.

The All Purpose A3 Reacher is slightly flatter than the A1 VMG and has less girth. This sail is particularly suitable if you have a less stable boat that accelerates easily with improved reaching capability. Typical wind angles would be 55 to 105 degrees in 3 to 20 knots of breeze.

The Runner is designed to be as stable as a symmetrical spinnaker yet incorporates a unique shape distribution that allows the sail to fly out to weather, away from the mainsail. This Runner is appropriate if you have a stable, powerful boat and you want to improve broad reaching to downwind capability in heavy air. This sail is made in medium to heavy and specialist nylons. Used in wind angles from 130 to 160 degrees in 10 to 25 knots of wind.

The Code Zero is a spinnaker-genoa hybrid and the smallest asymmetrical spinnaker allowed by the IMS rule. It is a specialty sail built out of high modulus materials for light air upwind performance and tight reaching. This sail aims to increase performance at the lower end of the jib ranges. The Code Zero would be designed for wind angles of 46 to 80 degrees in up to 14 knots of wind. A Code Zero will typically have a mid-girth of 75% of the foot length so it measures as a spinnaker, but has a much bigger area than a genoa.

All ocean racing yachts whether carrying asymmetrics or symmetrics benefit from a Code Zero type sail. A crossover chart shows how well they fit into the inventory.

A5-A7 sails are very similar to a Code Zero but are often set on a fractional halyard instead of a masthead halyard. They can be effective in place of a Code Zero to extend spinnaker range under IRC sail restrictions. They are usually made from a laminate material and set on a furler for ease of handling.

Symmetric Spinnakers

Not all race boats are choosing to fly asymmetrics. Some Class rules stipulate that only symmetric spinnakers may be used, and some heavier styles of boat that cannot generate the higher downwind speeds which promote closer apparent wind angles find it preferable to sail deep with a symmetric anyway.

The VMG S1 (light running and reaching spinnaker) is a symmetric spinnaker designed for tacking downwind in light air. The sail is designed with narrower girths in the upper portion and a leech profile that is symmetrical and flies closer to the rig. Typical wind angles would be true wind angles of 80 to 150 degrees in up to 7 knots of wind. They are usually manufactured from 0.5 oz spinnaker nylon. Tight true wind angles are the order of the day with VMG.

The AP S2 (light-medium running spinnaker) is designed to be the work horse of any inventory and covers a large range. It has fuller girths and is designed to lift and fly away from the boat. The top 10% of the sail, being flatter, allows the spinnaker to set away from the rig before the body of the sail curves down. The result is a sail that flies out to windward, away from the disturbed air of the mainsail and rig, in clear air flow. Optimum wind angles are around 170 degrees in wind speeds of 5 to 18 knots.

The AP Reacher S3 (medium reaching spinnaker) is normally manufactured from 1.0 oz spinnaker nylon or laminate spinnaker fabric. For larger boats the S3 is skewed towards reaching angles between 85 to 135 degrees in 9 to 24 knots of wind. This design is generally flatter with a smaller head angle and less shoulders than a running spinnaker.

The AP Runner S4 (medium-heavy running spinnaker) is designed to get the boat downwind in stronger breeze conditions. It has a large head angle, big shoulders and the fullest girths a sail can fly. The cross sectional shape of the sail is more elliptical, which increases the projected sail area while maintaining the spinnaker’s stability The optimal wind angle for this is between 130 and 170 degrees in 18 to 26 knots of wind.

The Reacher S5 (heavy reaching spinnaker) is designed for use with the pole on the forestay for closer downwind angles. The sail has a flat shape and strong construction for heavy air use. Wind angles of 95 degrees plus would be appropriate for this sail in 25 plus knots of wind

The Runner S6 is designed to be used on running legs in stronger winds.

The key to perfect sail selection is the crossover chart. If you are buying new sails your sail designer will produce a crossover chart showing which sails are most suitable for particular wind angles and speeds. Using a crossover chart ensures that your performance is always optimised in particular conditions and that your sails are not over-worked and subsequently damaged.