2 min read · Updated 19 May 2026
A trysail is a small, strong storm sail set on the mast in place of the mainsail in severe weather — a sail built for control and survival rather than speed, and the heavy-weather partner to the storm jib. With these two storm sails a yacht can keep a balanced, manageable rig when conditions turn dangerous, and together they complete a properly seaworthy sail wardrobe.
What the trysail does
There comes a point in heavy weather where reefing the mainsail is no longer enough, or where the main or its boom is damaged. The trysail is the answer. It is a small triangle of heavy, strongly reinforced cloth set on the mast, and crucially it is loose-footed — not attached to the boom — so it can be set and trimmed with its own sheets, clear of a boom that may be thrashing or lashed down.
Set in place of the mainsail, the trysail keeps just enough drive aft to balance the rig and let the boat steer and make way. It is the sail that, with a storm jib forward, turns a yacht's normal sail plan into a tiny, robust, balanced pair for survival sailing.
When and why it is carried
The trysail belongs to the same severe-weather toolkit as the storm jib, and the two are designed to be used together. In a gale, a boat working under storm jib and trysail has a low, strong, balanced rig that keeps it under control — able to hold a course, heave to, or claw off a hazard — when its ordinary sails would be unmanageable.
For offshore and category racing, carrying a trysail (or an equivalent means of heavily reducing mainsail area) is commonly required, along with the ability to set it, under the same safety regulations that mandate the storm jib. The requirements are defined by each race's safety category and notice of race, as touched on in our offshore regatta guides. An inshore one-design racing buoys in protected water will not carry one, but any yacht heading offshore must. For the complete inventory and how the sails are built, see the sails pillar and the boat page.
Frequently asked questions
- What is a trysail?
- A trysail is a small, heavily built storm sail set on the mast in place of the mainsail in severe weather. It is loose-footed — not attached to the boom — so it can be set safely and trimmed clear of a thrashing boom, and it keeps a yacht balanced and under control when the mainsail, even deeply reefed, would be too much.
- When do you use a trysail?
- A trysail is set in genuinely severe conditions, when reefing the mainsail no longer reduces sail enough or when the main or boom is damaged. Combined with a storm jib, it gives a yacht a small, strong, balanced rig for survival sailing — keeping steerage and the ability to work to windward in a gale.
- What is the difference between a trysail and a storm jib?
- They are the two storm sails and they work together. A storm jib is the small heavy headsail set forward; a trysail is the small heavy sail set on the mast in place of the mainsail. Used together they replace the boat's normal upwind sails with a tiny, strong, balanced pair for severe weather.
- Is a trysail compulsory for offshore racing?
- For many offshore and category races, yes. Offshore safety regulations commonly require a trysail (or an equivalent means of heavy-weather mainsail reduction) alongside a storm jib, and require that the crew can set it. The exact requirements depend on the race's safety category and notice of race.