Depending on their intended use, gennakers differ in size, shape, and the materials from which they are made.
The sail is flown with a free‑flying luff ahead of the forestay. The tack is trimmed either with a tackle system or fixed with a strop to a dedicated bow fitting or an extendable bowsprit. The gennaker is hoisted using the spinnaker halyard. The sheets are attached to the clew: the leeward sheet runs aft to a block at the stern, while the windward sheet is led forward around the outside of the forestay and then aft for gybing.
Compared to spinnakers, gennakers are significantly easier to hoist, fly, trim, gybe, and douse. For this reason, they are often used on cruising yachts as an effective and user‑friendly sail for reaching and close‑reaching courses.
Modern racing yachts also carry gennakers as a standard part of their sail inventory.
A gennaker is not suitable for dead‑downwind sailing. In this position, the sail falls into the wind shadow of the mainsail, loses power, and collapses.
