There are so many topics when it comes to equipping a boat that the storm jib is often overlooked. Selection and purchase are not taken serious. Surprisingly, the standard literature provides nothing here. Even the 32nd edition of the German Seamanship, the Handbook for Yachting from 2019 only mentions this important sail. Adlard Coles’ reference book Heavy Weather Sailing offers no recommendations in its 450 pages. Further, the standard work by long-time American sailmaker Tom Whidden on The Sail contains nothing at all about the storm jib.
Common storm-sails recommended via internet are offered in surprisingly light fabric. Further, the storm jib is supposed to be pulled up over the rolled-up headsail with a kind of stocking. How is that going to work when it is blowing at 50 km/h or more? Apparently, for the sake of good order, the storm jib is stored in the locker, and the engine is relied upon for cruising.
In high winds and corresponding sea conditions, a flat profile made of robust fabric is required. The sail geometry and the sheet guided through the corridor of lower and upper shrouds are important. The sail should be hoisted quickly. A pro forma solution does not help here. In strong winds, you cannot motor against heavy seas with the Swede 55. The boat, with its slender bow, dives deep at the front and pitches badly. This immediately makes everyone on board feel sick. Besides, sailing is safer.
A glance at the Beaufort scale shows what this means: four Beaufort are 20–28 kilometres per hour, six are 39–49 kilometres per hour, and nine are 75–88 kilometres per hour. This range represents a threefold increase in wind speed. From brisk cycling to cruising speed in a car driving on a motorway. Try holding your hand out of an open window. Only wind forces of 9–11, i.e. wind speeds of 89 to 117 kilometres per hour, are considered as storm.
Determining the size of the headsail using the LP measurement
The internet offers the following rule of thumb for calculating the size of a storm jib. It is based on the length of the forestay. The rigging and sail making nomenclature refers to this as the so-called T measurement. Regardless of which headsail is involved, whether Genoa or storm jib, the headsail area is always determined using the so-called LP measurement. The abbreviation stands for the English term luff perpendicular and refers to the distance from the clew to the luff. As the English term suggests, it is measured at a right angle from the head stay/the luff.
Recommended storm jib sizes based on this formula
head stay length T
T2
Storm jib Race boat 5 % of T2
Storm jib cruising boat 3-3.5 % of T2
13.70 m
187.7
≈ 9 m²
≈ 6–7 m²
These storm jib areas are ensuring that the boat remains controllable in a storm on the open sea and is not too fast. However, this means that when tacking into the shelter of a lee coast in sailable winds, it does not make much headway. In my experience, this boat performs quite well with a 16 m² strong wind jib in reasonable seas. When it comes to getting to calmer waters or the nearest harbour quickly in coastal waters such as the Baltic Sea or the Mediterranean, height and speed are the deciding factors in getting out of trouble.
Downwind ride or up wind performance?
Swede 55 is a slim, light and slender boat. Accordingly, reefing is done early, and the jib is replaced by the next smaller sail. From occasional tests, I remember that the boat still tacks well and quickly at around eight wind forces with 15.5 m² storm jib and a triple-reefed 18 m² mainsail. When the sea washed over the coaming, we continued with the storm jib alone, having removed the mainsail. As the centre of effort of the sail was then unfavourably far forward, the rudder had to be be kept turning the boat slightly windward, otherwise the storm jib pushes the bow out of the wind. If the bow folds away when sailing too deep by mistake, the sheet is eased, a run is taken and the sheet is pulled tight again and luffed.
Experience with the 15.5 instead of 18 m² heavy duty jib
According to the 1975 sail plan, naval architect Knud Reimers had specified a storm jib with a 10.60 m luff, 8.50 m leech, 4.30 m foot and an LP measurement of 3.40 m resulting in 18 m². My father and I thought this was too big at the time. So, different from Reimers’ recommendation, Gamle Swede sailed for decades with the aforementioned 15.5 m² storm jib. It was hoisted on an aluminium head foil by the American sailmaker Hood, type Gemini (offered by Reckmann at the time named Zwilling).
This sail, made of heavy 450-gram cloth, was affectionately called the fear rag aboard. On many windy days, I threaded it into the head foil, preparing it with a certain trepidation. At some point, the sail became bulgy and the worn clew looked like corrugated iron. It served well for 3 1/2 decades. That’s how long a conventional Dacron sail without a furling system lasts.
Gamle Swede ready to depart in Grömitz/Baltic Sea with the storm jib prepared – Photo Swedesail
The first 8.3% heavy-duty jib of Gamle Swede
head stay length T
T2
heavy-duty jib 8.3 % of T2
Knud Reimers’ recommendation 9.6 % of T2
13.70 m
187.7
≈ 15.6 m²
≈ 18 m²
The original heavy-duty jib with wavy clew at Hood Gemini head foil – Photo Michael Amme/Swedesail
Together with a conventional reefing system for the mainsail, the boat is sailed safely and smoothly with the first, second or, occasionally, third reef. This reefing system was perfected in the 1970s with the reefing line running through the boom and guided aft to the cockpit for quick reefing. It works well with today’s Dyneema ropes. The hardware is well documented by the spar maker and spare parts (pulleys and bolts) are quickly available by Seldén.
The former 15.5 m² storm jib and the previous mainsail reefed 2 x down to 26.5 m² in 7 Beaufort – Photo Michael Amme/Swedesail
This limits heeling and allows it to tack even in strong winds and heavy seas. Another benefit of this sail with its high clew is the forward visibility. Thanks to the clear view, you can safely tack up the narrow Trave river with all its ferries and shipping traffic in Travemünde.
Gamle Swede with previous 42 m2 mainsail and handy 15.5 m2 jib upwind in Travemünde – Photo Uli Eichler/Swedesail
With a storm jib slightly smaller than that recommended by Reimers, and based on experience with the previous boat, a slightly shorter Lotus-type touring cruiser that was pretty slender, Gamle Swede set sail from Västervik in eastern Sweden in June 1980.
Measurements: Luff 10 m, leech 8.33 m, foot 4.14 m, LP 3,13 m, 15.56 m², 8.3 % of T²
When the wind dropped to five Beaufort, this headsail was no longer sufficient, requiring a quick switch to the jib. As became apparent over the years, the decision at the time to opt for the smaller storm jib, which deviated from the Swede 55 specification, was wrong.
Sailing on River Trave with full main and good visibility thank to the high clew headsail – Photo Uli Eichler/Swedesail
New 19 m² heavy-duty jib
When Lübeck sailmaker Arnd Deutsch and I planned this new storm jib, the aim was to create a versatile heavy-duty jib driving the boat already at 3 Beaufort.
A wear-prone furling system with poor sail shape was no choice for Gamle Swede, where sailing pleasure and delighting up wind courses matter. On the other hand, the days when my sailing friends and I crawled around on the foredeck several times a day to hoist a suiting headsail are gone. Further sheet routing between the lower and upper shrouds was not easy. The solution was a carefully planned jib geometry and a robust sail made of heavy 450 g polyester cloth instead of the previously recommended 350 g cloth.
Experience with the 10% heavy-duty jib
So Deutsch tailored the jib with a proven high clew. The new jib is an interesting compromise. It works well in common wind strengths close-hauled. The sail has three battens. In the evening, it is rolled up parallel to the battens and stored in a waterproof and UV-resistant tube on the cabin roof and will probably last a long time.
Together with the new 44 m² mainsail, whose area can be quickly reduced with a total of three reefing rows in just a few simple steps, the boat is now versatile to sail. Thanks to 3 m² more at the headstay and even slightly overlapping geometry. The heavy-duty jib and the first reef now provide 54 m² instead of 49 m² previously. The new jib and second reef turn out with 47 m² instead of 42 m² previously.
Details of the new heavy-duty jib
Sail dimensions: Luff 10.70 m, leech 8,75 m, foot 4.55 m, LP-measurement 3.52 m, area 19 m2
Size due to headstay formula: 10 %
Percentage of regular 30 m2 jib: 63 %
Cloth: Dacron with yellow Vectran in weft-yarn direction by Dimension-Polyant, type Vectron, named VEC 100
Cloth weight: 10.5 ounces = 450 g/m2 (instead of 350 g, as specified for Swede 55)
Cut: seven horizontal lanes
Commissioned: three battens with long top batten. Large reinforcements at top, base, and tack
Clew: sheet saving thick thimble instead of the thin ring commonly used today.
Extras: special luff strip suiting the Hood Gemini/Reckmann Zwilling head foil
Stowed in tube: Weathermax 80, full-length ≈ 4 metre zip fastener
Sailmaker: Arnd Deutsch, Teerhofinsel, Bad Schwartau near Lübeck/Germany
Safe sailing with reliable and lasting cloth matching to the wind – Photo Michael Amme/Swedesail
Thanks to today’s weather apps, the wind is predicted reasonably certain several days in advance and pretty reliable in the morning before departing. Cruising on common distances is no longer a journey into the unknown. So this sail is a compromise for safe sailing on the Baltic Sea in normal conditions up to wind force 8. It will not be suitable for the Adriatic Sea in Bora, the Gulf of Lyon in Mistral or for crossing Cape Horn. In these cases, a real fear rag in the size as mentioned above is required. Bernard Moitessier completed his legendary voyages in the 1960s with his 16-tonne long-keel yacht Joshua with a double-reefed 6 m² jib and a true 5 m² storm jib.
Photo on top by Swedesail: Drying the heavy-duth jib in Passathafen of Travemünde aboard Gamle Swede. Published December 4, 2025, updated December 4, 25. Subscribe to the free newsletter and you won’t miss new articles.
