A Strategic “Sail Plan”

October 21, 2011 – 11:46 pm

To sail outside of one’s safe harbor a skipper should have a strategic sail plan which enables seamanlike boat handling in heavy air and sea conditions.  Unlike storm tactics, this sail plan is a storm strategy, a methodology that enables skipper and crew the ability to reef and continue to sail efficiently and under control in heavy air.

Preparing the boat… to implement this strategy by design of a sail and rig configuration which will enable dynamic movement of the Center of Effort as needed, for depowering and reducing heel in heavy air, while retaining enough driving force to keep the boat on its feet through heavy seas.

The  masthead rigged sloop… the target for this discussion is a “boomers” sailboat of the twentieth century, with an overlapping genoa + modestly sized mains’l.  This rig has withstood the test of time in light to medium air, but can be a handful as the wind picks up, presenting a myriad of possibilities for reducing sail.

A technical review… the knowledge that the force on the sail plan is defined by the Geometric Center of Effort of the combined sail area (main + jib).  This force is reflected to the boat’s Center of Lateral Resistance. The design of the hull and keel appendage will translate this wind energy to forward momentum.  In turn the helmsman will steer using the angle of attack and sail trim to achieve a balanced helm and heel angle.

Sail Plan… starts with a set of rigging alternatives for reducing sail area, thereby changing the Center of Effort. One’s mileage may vary on the following sail and rig configurations; in descending order of effectiveness.

Rig (sail plan) methodology as it applies to your headsail:

  1. Storm Staysail -Cutter Rig with an inner forestay at or near the spreaders, parallel and well aft of the forestay. This sail plan is probably the most efficient rig design for moving the center of effort aft and down.
  2. Storm Staysail – Solent Rig (aka inner forestay) with an inner forestay that leads near or at the masthead to a fitting aft of the headstay. This sail plan will move the center of effort down and aft (to a lesser degree than the cutter)
  3. Storm Jib hanked on forestay, either masthead or fractional.  This is a reduction in sail area (and flatter shape) but it moves the CE forward and down. Depending on wind force this may at least provide additional drving force to power through the seas.
  4. Storm Jib with luff sleeve which fits over a furled genoa.  Not a common solution — or an intuitive solition for good sail shape. Perhaps adding windage to the sailplan thus negating the attempt to move the CE.
  5. Reefed Genoa – The headsail area is reduced by partial furling.  This is the common way to reef – may work well in medium high winds.  In high winds better than nothing.  It may be effective to roll up to 20% of the sail but probably not much more. The problems arise when the sail shape becomes more full and negates the intended effect. This is where luff padding such as foam or rope may help to keep the sail shape flat.  A reefing point on the foot may work wonders to maintain a firm luff tension.

Rig (sail plan) methodology as it applies to your Mainsail:

  1. Storm Trysail -Mounted on its own track on the mast, it has a loose foot and clew that is rigged with substantial hardware to trim the sail to a very flat profile. Brings CE forward and down.
  2. Main Reef – Jiffy reefing allows for quick sail area reduction while maintaining a tight luff. Rig at the boom end should allow for firm outhaul tension along the foot of the sail. Excess sailcloth area should be contained neatly and secured with reef nettles – be sure that they are NOT creating a stress point on the sail. All of the stress points should be distributed to the luff and foot. Brings CE forward and down.

For the sloop, the cutter rig is the most effective in reducing sail area by moving the center of effort downward and amidships. Because the Staysail is on an inner stay it is a much more effective storm sail than a jib on the forestay.

A storm sail (trysail, staysail, or jib) will be built with heavier cloth, stronger corner patches and rings, and cut flatter for minimum sail camber (shape) when trimmed for heavy air.

Sail Plan

Masthead Sloop

Reefing: To move the Center of Effort down and amidships, achieving balance with the Center of Lateral Resistance.

Sloop or Cutter:

  • Reef main or deploy storm trysail
  • Deploy inner stay (if so equipped)
  • Drop genoa/deploy storm jib or staysail
  • Roller reef genoa, or deploy sleeved storm jib

Reducing Mains’l Area:

  1. Storm Trysail
  2. Reefed Mains’l
  3. Furled Mains’l

A Sail Plan you can count on; Prepare your boat and crew to Reef Early and Often

Fair Sails…

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