Storm Jibs & Trysails.
Sized By The Numbers.
Built to World Sailing Offshore Special Regulations. Enter your rig measurements below and we will calculate the maximum compliant dimensions and point you to the right sail, no guessing, no under-building your heavy weather wardrobe.
Storm Jib Calculator
Foretriangle Height (I Measurement)Where to find your I measurement:
The vertical height of the foretriangle, measured from the deck at the base of the forestay to the forestay attachment point on the mast. It is on your class measurement certificate, your sail plan, or your one-design class rules.
Trysail Calculator
Where to find P and E:
P is your mainsail luff length (the black band to black band measurement on the mast). E is your mainsail foot length (the black band to black band measurement on the boom). Both are on your class certificate, rig plan, or your current mainsail's spec sheet.
What The Rules Require.
Storm Jibs — OSR 5
Area limit. Maximum area not greater than 5% of I², where I is the height of the foretriangle. Max Area = 0.05 × I²
Luff length. Luff length must not exceed 65% of the foretriangle height. Max Luff = 0.65 × I
Area calculation. Storm jib area is calculated using the official OSR formula: Area = 0.255 × Luff × (LP + 2 × HW), not simply base × height ÷ 2.
Luff attachment. Must have a permanently attached, independent method of attaching to the stay, not reliant on any luff groove or furling foil.
No battens. Storm jibs shall have no battens, so they can be set and furled quickly in extremis.
Trysails — OSR 4.26
Area limit. Area not greater than 17.5% of mainsail luff (P) × mainsail foot (E). Max Area = 0.175 × P × E
No headboard, no battens. Keeps the sail simple to set and drop under load.
Markings. Sail number and letters on both sides, as large as practicable.
In-mast furling. On boats with in-mast furling, the trysail must be capable of being set while the mainsail stays furled.
Luff attachment. Independent of the mainsail track or luff groove, same principle as a storm jib's independent stay attachment.
Materials. HMPE (Dyneema/Spectra) and similar high-modulus polyethylene fibres are permitted for luff reinforcement and construction. Aromatic polyamides (Kevlar, Twaron), carbon fibre, and similar exotic fibres are not permitted in storm jibs or trysails.
Materials. Same restriction as the storm jib: no aromatic polyamides or carbon. HMPE and similar high-modulus fibres are permitted.
Shop Storm Jibs & Trysails.
Storm Jib
OSR MoMu 0–2 compliant, cross-cut construction, high-vis cloth. Available in Warp Luff, Hanks, or Luff Tape attachment.
Shop Storm Jibs → Custom Cut To Your RigTrysail
Built to OSR 4.26 and sized to your mainsail's P and E. No fixed size chart, tell us your rig and we will quote it.
Shop Trysails →