Do you need a set of storm sails?


Do you need a set of storm sails?

by Calanach Finlayson Jun 22 08:00 UTC

Storm sails are an essential offshore safety feature when cruising or racing © Carlo Borlenghi / Rolex

A good set of Storm Sails can be a free get out of jail card if you get caught in heavy weather. A necessity for offshore passages cruising or racing and a prudent safety feature for most cruisers.

What are Storm Sails?

A typical set consists of two heavy-duty sails constructed from a durable woven fabric such as Dacron: a jib and a main sail. These are often brightly colored to aid visibility, which could be crucial in a search and rescue (SAR) situation.

storm jib

A storm jib is the smallest jib carried on board and is often separate from normal sail inventory, although some boats choose to have a number 4 jib that meets the requirements of a storm jib.

A storm jib should be hoisted on a suitable forestay, ideally aft of the main forestay. This brings the center of effort aft, towards the middle of the boat, which helps maintain balance at the helm.

Some storm jibs include structural luff rope or wire and therefore do not need to be attached to an existing forestay.

When an inner forestay is not possible, a storm jib can be hoisted on the primary forestay. The method of attachment should be independent of any head profile / luff groove used. For example, if normal jibs are hoisted in a TuffLuff or Harken foil, the jibs should have soft hanks wide enough to pass around the forestay with or without the foil.

Yachts with hank sails can simply use standard hanks to attach the storm jib in the same way as standard jibs/genoa.


For cruisers fitted with furling headsails, an option is available to hoist a storm jib on the furled genoa with an additional sleeve. A Dacron sleeve is passed around the furled sail with the storm jib attached to the back edge.


A storm jib is usually high-sheeted and can either be sheeted via the same wire as the genoa or by using an additional outside wire located at rail level.

Trysail Storm

A storm sail (or tri-sail) replaces the mainsail in extreme or heavy weather conditions where the fully reefed mainsail still has too much sail area. Some owners will opt for a mainsail with a deep third reef, which will make it easier to reduce/increase the sail area in changing conditions. However, even a heavily reefed mainsail cannot replace a test sail in the most extreme conditions.

A test sail is also hoisted to the mast but must be independent of the mainsail. For boats with slugs/cars on the main, one of the most popular options is to install a secondary mast track parallel to the primary track or groove so that the test sail can be hoisted without removing any of the main wagons/slugs. For main luff rope systems, the trysail can be hoisted in the same luff groove. Other methods exist, including simple Velcro straps to attach the tri-sail to the mast.

A storm trysail does not attach to the boom but folds directly onto an aft block.

Storm sail sizing

The World Sailing Offshore Special Regulations (OSR) govern the rules for boats taking part in recognized offshore races, including the storm sails they must carry. Although there is no such rule for cruise ships, the information provided in the OSR is based on best practice and is updated at least every two years to reflect the latest knowledge in safety at sea, including lessons learned from incidents at sea.

OSR 4.27 storm and heavy weather sail specifications include the requirement for “highly visible” colors and the ability to hoist a jib “independent of a luff groove”. Maximum sail areas are also stipulated as follows, which may be a useful guide for non-racers:

storm jib

Area of ​​13.5% of the height of the front triangle squared
For Cat 2 racing this reduces to an area of ​​5% of the foretriangle height squared with a maximum luff length of 65% of the foretriangle height

For example, a typical 35ft yacht with a fore-triangle height of 14m:
Max. storm boom area = (5 / 100) x 142 = 9.8 m2

storm tent

Area not exceeding 17.5% of mainsail winch (P) x mainsail foot length (E)
For sails manufactured after 2011: the storm sail area calculated as follows (0.5 x leech length x shortest distance from tack to leech)



Storm sails can be invaluable for surviving inclement weather and for the extra weight / minimal storage space required, they are easy to transport. The exact rig configuration should be carefully planned to be as simple and sturdy as possible. The OSR sets out the rules regarding storm sails for racers, but also provides helpful tips and best practices for cruisers.

Like all safety equipment, it is absolutely essential to familiarize yourself with the adjustment of your storm sails, before setting out on a longer crossing where they may be necessary.

If you would like to know more about storm sails or would like advice on the best storm sails for you, contact us at or click the link below to see our full range of storm sails.

Buy storm sails


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