Gennaker

A gennaker is a type of downwind sail used on sailing yachts. The term, often spelled gennaker or genaker, denotes a sail that blends characteristics of a gennaker and a spinnaker (or of a genoa and a spinnaker). It is designed to improve performance on broad reaches and downwind courses while being easier to handle than a full symmetric spinnaker for many crews.

Design and construction: A gennaker is typically an asymmetrical sail with a curved luff, cut to balance power and stability at downwind angles. It is usually flown from a bowsprit or a dedicated sprit and flown using a halyard and two sheets (one on each side) for trimming, sometimes with an additional tack line. Materials are commonly lightweight nylon or laminated fabrics. The sail’s shape allows it to hold form without the heavy rigging required by a large symmetric spinnaker.

Usage and handling: Gennakers are popular on cruising and racing yachts for improving downwind speed and acceleration without the complexity of a large double‑sheeted spinnaker rig. They are deployed by hoisting the sail on its halyard, attaching the tack to the sprit or bowsprit, and trimming with the two sheets. They can be reefed or replaced with other downwind sails such as a code zero or a full spinnaker depending on wind strength and course.

Variants and context: The gennaker fills a niche between a genoa and a spinnaker, offering greater drive than a jib on broad reaches while remaining more manageable than a large spinnaker. It is one of several specialized downwind sails used to optimize performance at various wind angles.