POLED SPINNAKER TRIM
The following are basic concepts necessary for poled 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.
There are only two elements required for controlling a poled spinnaker. These are the pole itself and the spinnaker sheet. The pole is controlled in both vertical and horizontal movement. The sheet is positioned fore and aft depending on point of sail and is trimmed in or out as required.
1. Get the boat headed on the course you wish to make and set the main sail appropriately. Hoist pole to a convenient height.
2. Hoist spinnaker and trim the pole (adjust the afterguy) so that the pole is level and at right angles to the apparent wind. Use the masthead wind indicator or put a telltale on the pole. The pole should be close to 180 degrees from the boom.
3. Trim spinnaker sheet to allow the sail to fly. Let the boat build up speed. After boat has stabilized in speed ease the spinnaker sheet out until the top 1/3 of the spinnaker luff (windward edge of sail) begins to collapse. Stop easing sheet at this point and observe the height of the clew to which the sheet is attached. If the clew is higher than the pole the pole needs to go up, if it is lower the pole needs to come down. You objective is to make both the windward clew (on the pole) and the leeward clew (attached to the sheet) to be at the same height above the deck.
4. Adjust the pole height by raising or lowering the pole lift halyard (attached to either the pole outer end or upper bridle) and by raising or lowering the inboard end of the pole on the mast track so that the pole is level.
5. Repeat steps 3 and 4 to fine tune trim.
6. Tighten the foreguy (pole downhaul) to prevent the pole from lifting.
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 pole is almost straight ahead (keep it a foot or so off the headstay) and is generally low (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 middle 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.
The foreguy (sometimes called the pole downhaul) is important for safe operation of the pole. The wind is trying to lift the spinnaker and in stronger winds will not only lift the sail but will raise the outer end of the pole as well. The mast fittings for the pole etc. are built for loads in the horizontal plane and could fail if the pole is allowed to load up substantially out of the horizontal plane. The foreguy is a line used to prevent the pole from raising and to keep it horizontal. It is attached either to the end of the pole or to a bridle on the bottom of the pole and runs through blocks back to the cockpit. After adjusting the pole (steps 1-5 above) secure the foreguy. Remember to release it when the pole needs adjusting again then retighten it.
As noted in “3” above you are trying to get both clews to be at the same height above the deck. When the pole and the clew are at this ideal height the sail should be stable. If the pole is too high or too low the sail becomes unstable and will collapse. The sail will also become unstable if the pole is adjusted too far aft. Having the pole too far forward usually provides a stable sail but you are not operating as efficiently as you could. Moving the pole forward in strong wind is sometimes done to keep boat and sail under control.
Pull the Chutescoop down to cover the sail. Jibe the boat and main sail. Switch the pole to the other clew and position the pole as in 1-5 above. Set the sail as described above. Using the Chutescoop separates the jibing operation into steps one or two people can handle and takes the load off the pole.