Sailing Downwind: Spinnakers and Pole Handling

Sailing downwind with a spinnaker is one of the most enjoyable and rewarding experiences in sailing, but it also demands careful preparation and crew coordination. A spinnaker is a large, lightweight sail flown ahead of the forestay when sailing with the wind behind or across the quarter, and it can add significant speed to a downwind leg. Understanding the differences between symmetrical and asymmetrical spinnakers, how to set and gybe them, and how to manage the spinnaker pole is essential for any sailor who wants to make efficient progress off the wind. This guide covers spinnaker types, pole handling, gybing procedures, and safety considerations.

Symmetrical vs asymmetrical spinnakers

The two main types of spinnaker are symmetrical and asymmetrical, and they differ in both shape and handling. A symmetrical spinnaker is shaped like a parachute, with two identical sides, and it requires a spinnaker pole to hold the windward clew out to windward. The sail is flown with the pole on the opposite side from the main boom, and it is gybed by moving the pole from one side to the other. Symmetrical spinnakers are traditional on racing boats and on cruising boats that sail deep downwind angles.

An asymmetrical spinnaker, often called an asymmetric or gennaker, has a distinct luff and leech, with one side longer than the other. It is flown without a spinnaker pole, using a bowsprit or a tack line attached to the bow. The sail is gybed by moving the clew from one side to the other in front of the forestay, similar to gybing a genoa. Asymmetrical spinnakers are simpler to handle than symmetrical ones, and they have become the standard on modern cruising boats and many racing designs. They are particularly effective on reaching angles but less efficient on dead downwind angles, where a symmetrical spinnaker or a wing-on-wing setup performs better.

Spinnaker pole setup and handling

For boats that fly a symmetrical spinnaker, the spinnaker pole is a critical piece of equipment. The pole is attached to the mast via a track and car system, allowing it to be raised and lowered to match the sail's height. The outboard end of the pole holds the spinnaker guy (the windward sheet), and the pole is controlled by two lines: the topping lift, which holds the pole up, and the foreguy (downhaul), which holds it down and forward. The afterguy (bracket) controls the pole's fore-and-aft position.

Setting the pole correctly is essential for proper spinnaker trim. The pole should be roughly perpendicular to the apparent wind, forming a square with the sail. The height should be adjusted so that the clews of the spinnaker are at roughly the same height, creating an even sail shape. If the pole is too low, the sail collapses at the top; if too high, the foot sags and the sail becomes unstable. The pole should never be allowed to rest on the forestay, as this can damage both the pole and the stay.

Setting the spinnaker

The procedure for setting a spinnaker varies depending on the boat and the type of sail, but the general approach for a symmetrical spinnaker is as follows:

1. Pack the spinnaker into its bag or launcher with the three corners — head, tack, and clew — accessible and labelled.
2. Attach the halyard to the head, the sheet to the clew, and the guy to the tack. Ensure all lines are clear and not twisted.
3. Attach the pole to the mast and rig the topping lift, foreguy, and afterguy. Pre-set the pole on the leeward side if doing a leeward set, or on the windward side for a windward set.
4. Bear away to a downwind angle to blanket the spinnaker behind the mainsail, reducing the force on the sail as it is hoisted.
5. Hoist the spinnaker quickly to the top of the mast. Once hoisted, pull the sheet and guy to trim the sail, and adjust the pole to the correct position.
6. Bear away or head up to the desired sailing angle and trim the sail for maximum speed. Check that the sail is full and that neither the sheet nor the guy is chafing.

For an asymmetrical spinnaker, the procedure is simpler: attach the tack to the bowsprit or bow, the sheet to the clew, and the halyard to the head, then hoist and trim. No pole is required, which reduces the number of lines and the complexity of the manoeuvre.

Gybing a spinnaker

Gybing a symmetrical spinnaker is one of the more complex manoeuvres in sailing, requiring coordination between the helm and the crew. The standard procedure is an end-for-end gybe, where the pole is disconnected from the mast, moved to the new windward side, and reconnected. The steps are:

1. Bear away onto a run, so the wind is directly behind and the spinnaker is blanketed by the mainsail.
2. Disconnect the inboard end of the pole from the mast, while simultaneously releasing the old guy and pulling the new guy through the pole end.
3. Swing the pole across the bow to the new windward side, and reconnect it to the mast.
4. Trim the new sheet and guy, and adjust the pole height and position for the new tack.
5. Gybe the mainsail, and head up to the new course.

Gybing an asymmetrical spinnaker is simpler: the sheet is released from the leeward side and pulled in on the new windward side, while the sail flies in front of the forestay. The key is to keep the sail full during the transition — easing the sheet too quickly causes the sail to collapse, while trimming too hard before the gybe is complete can backwind the sail against the forestay.

Snuffers and socks

A spinnaker snuffer, or sock, is a tubular fabric sleeve that slides over the spinnaker to collapse and stow it. The snuffer is hoisted with the sail and remains at the top; to douse the sail, a control line pulls the sock down over the sail, collapsing it gradually. Snuffers have made spinnaker handling accessible to short-handed crews and cruising boats, as they eliminate the need to gather a large flapping sail manually. For a cruising boat with a small crew, a snuffer is strongly recommended for both asymmetrical and symmetrical spinnakers.

Safety considerations

Downwind sailing with a spinnaker carries specific risks that require attention. The most common is a spinnaker broach, where the sail pulls the bow down and the boat rounds up uncontrollably, potentially laying the mast in the water. Broaches are caused by sailing too high an angle with too much sail area, and they are prevented by bearing away before the boat rounds up and by easing the sheet promptly if the sail begins to overpower the helm. A spinnaker should be doused early if wind strength increases — waiting too long can make the sail impossible to control and lead to a Chinese gybe or a knockdown.

All crew handling the spinnaker should wear life jackets and safety harnesses, and no one should stand in the bight of a spinnaker sheet or guy. The loads on spinnaker sheets can be substantial, and a snapping line can cause serious injury. For boats sailing shorthanded or in heavy conditions, the safety equipment checklist and the cold weather sailing guide provide additional safety guidance. For sailors developing their skills, the sailing certification guide covers the training that includes spinnaker handling. And for those looking for a boat equipped for downwind sailing, the sailboats for sale on Owning include cruising and performance designs with spinnaker gear.