ASYMMETRICAL SPINNAKER TRIM
(Poleless or Cruising Spinnakers)
The following are basic concepts necessary for asymmetrical spinnaker operation. This is not a comprehensive treatise on spinnaker trim but should be adequate for getting started or for cruising. A spinnaker is another form of headsail. Think of it as you would if you were trimming a jib. Things you do to a jib to make your boat sail to windward or reach or run are the same as what you do to a spinnaker for similar points of sail. For a spinnaker the controls to make these adjustments are different than those of the jib but the principles are the same.
CONTROLS
There are only two controls on asymmetrical spinnakers. These controls are the sheet (or sheets) on the clew and the tack pendent on the tack of the sail. The sheet operates just as a jib sheet would and the tack pendent is used to adjust luff tension.
OPERATION
1. Get the boat headed on the course you wish to make and set the main sail appropriately.
2. Hoist the spinnaker and adjust the tack pendent to take any excess pendent out of the system. How tight you adjust the tack pendent depends on your point of sail. If you want to close reach pull the pendent tight so the tack of the sail is low. If you are broad reaching adjust the pendent so the tack is somewhere around the top of the pulpit.
3. Trim spinnaker sheet.
SPINNAKER SHEET BLOCK POSITION
Unless you have an oversized spinnaker the sheet block will never trim to the transom of the boat. The furthest aft the sheet will ever trim is determined by the close reaching trim of the sail. When close reaching the tack of the sail is close to the deck (to tighten the luff for better pointing ability). The spinnaker sheet should bisect the clew angle and come to the deck at that point. On most boats this point will be around the forward edge of the cockpit, somewhat behind where the genoa trims. All spinnaker blocks are mounted on the rail. All other points of sail require the block to move forward for optimum trim. Watch the foot and leech of the sail. If the foot curls inward the block is too far aft (too much foot tension). If the leech curls inward move the block back (too much downward tension).
SPINNAKER OR JIB HALYARD
Either halyard can be use with asymmetrical sails. Spinnaker halyards are preferred because they are above and in front of the headstay. Jib halyards are frequently used but when the sail billows out in front of the boat chafe of the halyard on the headstay may occur. If you use a spinnaker halyard then the tack of the sail needs to be in front of the headstay. If you use a jib halyard the tack is behind the headstay.
JIBING
The easy way to jibe is to pull the Chutescoop down completely then jibe the boat and main sail. When on the new course raise the sleeve and trim the sail. If you are using a spinnaker halyard the spinnaker swings in front of the boat (outside the headstay). If you are using a jib halyard the sail passes through the foretriangle just like your jib.