Asymmetric spinnakers, cruising chutes and gennekers are basically one and the same.
They are similar to symmetrical spinnakers in that they are light,colourful sails generally flown when the wind is on or aft of the beam,but that is where the similarity ends. The sail shape resembles a baggyloose luffed genoa and has a permanent luff, tack and clew. If a pole isrequired it is usually a small one in the form of a bowsprit.
The sail flies outside of the boat and so all lines should be rigged and led outside the shrouds, forestay and stanchions. Thespinnaker bag is attached to the leeward guardrail behind the genoa.Lead the tack line from the cockpit through a block on the bow, orthrough the bowsprit, and attach it to the tack.
Lead the sheets fromthe clew, outside everything, to a block on each quarter, then to awinch. Ensure the windward sheet is led outside of the forestay. Lead the halyard to leeward of the genoa and attach to the head of the spinnaker.
Head onto a broad reach so the main and headsail shelter the sail asit is hoisted. Adjust the tack-line until the tack is about 1m from thestem head block or bowsprit. Secure the tack line.
Put a couple of turns around the winch of the leeward sheet, leavingplenty of slack. Quickly hoist the halyard to the top of the mast, pullin on the sheet as the sail starts to fill, then furlthe genoa away.
Using the tack line, the luff can be tightened when close to the windand eased when off the wind. Ease the sheet until the luff starts tocurl, then tighten until it stops curling. If the spinnaker is overtrimmed the boat sails slower and weather helm will increase. Check byeasing the sheet.
To sail on a reach pull in the tack-line to straighten the luff and sheet in.
To sail further off from the wind, ease the tack-line and sheetallowing the sail to move in front of the boat providing more forwarddrive and less heel.
Asymmetrics get shielded by the mainsail when running downwind so thepreferred tactic is to broad reach and sail downwind in a series ofgybes. Whilst the course is longer, the speed is higher and bothmainsail and asymmetric work efficiently.
Simon Jinks - RYA Instructor and Examiner
Illustrations taken from the RYA Sail Trim Handbook by Rob Gibson