gennakers

Gennakers are a type of downwind sail used on sailing yachts to improve performance when sailing at broad reaches or with the wind from behind. They are a hybrid between a genoa and a spinnaker, intended to combine the power of a large foresail with the ease of handling associated with downwind sails. Gennakers are typically designed to be flown from a bowsprit or a foredeck attachment point, and they are cut as a single canvas with a curved luff to maintain shape as the sail fills.

In practice, gennakers are sized between a genoa and a full spinnaker and are rigged with a dedicated halyard and sheets. Many crews deploy gennakers using a sock or snuffer to help shepherd the sail off the deck and a pole or whisker pole to keep the sail clear of the water and rigging. The sail is usually trimmed with relatively hollow shape to maximize lift on broad reaches, while remaining manageable in gusty conditions.

Use and performance: gennakers excel on broad reaches and moderate beam angles where wind pressure is high but stability is important. They can offer stronger speed and better upwind drive than a genoa while being easier to handle than a traditional symmetric spinnaker. Handling techniques vary by boat and sailmaker, but the general approach emphasizes smooth halyard and sheet management, with attention to preventing flutter or collapse in gusts.

Origin and terminology: the term gennaker blends genoa and spinnaker, and the sail design has been embraced by many sailmakers since the late 20th century. Today, gennakers are common on racing and cruising yachts as a versatile downwind option. See also spinnaker and genoa.