The IRC rating formula makes provision for something called a heavy weather jib which is distinct from a storm jib.
A yacht with a furling foresail is given a rating credit but this credit is reduced if a heavy weather job is carried. By my calculations an IRC heavy weather jib is about 2.5 times the size of a storm jib.
A sail maker told me these jibs plug the gap between 25knots and use of a storm sail but I question the scenarios in which it will be pragmatic to switch over to such a sail.
Typically a cruising yacht will not knowingly venture out into a force 6+ and on those occasions when the wind pipes up worse than expected I think most cruising crews will tough it out with a couple of extra rolls rather than unfurl a 135% genoa in a 28knots wind in order to switch to a heavy weather blade jib.
The only use-case I can think of is that I am sitting in a Poole marina on a Sunday and must get back to Gosport that day against a steady 25knot wind. In such a case I could switch sails on the furler in dock.
I have a number 3 jib that satisfies the requirements as an IRC heavy weather jib and I find it a very useful sail.
Once the boat begins to get overpowered with the full number 2 genoa on the wind (about 25 kts AWS) it is much more efficient to change down to the smaller sail than to try to make to windward with a part-furled genoa.
If I anticipate going up wind in a 5 or above I would use that sail, and can happily carry it with progressively less main up to F8. It also has the benefit that it is high-clewed and very flat cut, meaning that it can be part-furled without significant loss of efficiency so even though I (sometimes) carry a storm jib I can't imagine when I would use it
However I sail a fairly heavy/seaworthy boat and I'm quite happy to set off in F7
Mine hoists on the furler, so does require the bigger Genoa to be dropped.
As I usually sail short or even single handed I am not a great fan of changing to a smaller Genoa underway so I normally try to chose the right size genoa at the start of the trip and stick to it (unless racing...).
The reason the heavy weather jib is so practical is that upwind it is as fast or faster than the number 2 down to wind speeds as low as F4, and can be carried (maybe partly rolled) in winds of F9 and above (not that I've tried the "above" bit).
Of course much depends on the boat - mine loves stronger winds and sailing in F7 is more fun than F3. A more modern design will have different handling characteristics.
Like Bedders I also carry a heavy weather foresail as well as a storm jib, but for cruising in my case. The storm jib is really no more than a steadying sail, downwind or hove to in extreme conditions. Going out for a brisk thrash in Poole Harbour in an F7-8 (or any other stretch of well sheltered water) the heavy weather foresail and triple-reefed main is a good combination. Has stopped many a weekend from being entirely wasted.
It might also serve if I ever do have to claw off the proverbial lee shore, but that's never happened yet, and never likely to.
Location: Summer bases Lamlash and Kip; winter Kip
Posts: 318
Re: IRC Heavy weather jib
I think your hunch may be right. As a "heavy weather" jib, 27 sq metres is a big sail.
You can do a fairly accurate, slightly conservative, guide to the sail area you need for any wind strength (and I'm assuming it's upwind you're considering here) if you can answer the following. What's your maximum apparent windspeed with everything up? And what sail area is "everything up"? The heeling force is what you're trying to place a limit on. This is proportional to apparent wind speed squared, multiplied by sail area, and for a given boat, the heeling force acceptable for one combination of speed and area is, near enough, acceptable for all other combinations.
In the case of my own boat, we're fully powered up at about 18 knots and 590 square feet, but right on the edge of out of control at 24 knots. So, for example, we can say its upper limit is 590 x 24^2 = 339840. Using that value, 339840, and putting in 30 knots as the wind speed, the maximum sail area would now be 378 sq ft. In fact, we'd have the full main (old-fashioned MH rig - only 210 sq ft) and No 3 blade up at 30 knots and that comes to 400 sq ft, but, from experience, it proves to be very close to the controllable limit of that combination. I've found it useful to plot the constant heeling force curve (i.e., Ax V^2 = 339840) for a graph of wind speed v. sail area and then patch in all my sail and reefing area combinations; removes much of the guesswork. You can do this for the lower limit of performance too to make sure you don't end up over-reefed and under-powered. The balance between headsail reduction and reefing the main is specific to the design of the boat and a matter of experience.
Of course, more properly, heeling moment is what we're trying to control, but that involves knowing the height of the centre of effort for every sail combination. The square on the velocity is what dominates when you're up to 25, 30, 35+ knots and gusting, making the height correction a bit academic.
"The only use-case I can think of is that I am sitting in a Poole marina on a Sunday and must get back to Gosport that day against a steady 25knot wind. In such a case I could switch sails on the furler in dock."
Yes, setting out with smaller than possible sails is rarely wrong, easier to shake out reefs that put them in, but:-
Hobbyhorse
Sailing never could, cannot now, and never will be able to be completed to a schedule.
I use a yankee jib of 65% foresail triangle on my furling jib which has, in fact, replaced the storm jib of 30% mainly because it can be rolled down smaller than the storm jib.
However, if I'm knowingly going to windward in much above a F4 I always move to the solent which doesn't roll and is good for up to about 30 knots apparent.
In all this a reliable forecast and changing down in plenty of time is key, so having to change down in 28 knots is the just reward for ignorance and improvidence.
I can confirm the challenge of changing headsails in heavy weather having had the #2 genoa halyard part in 23-28 knots off Cap Sicié October 23 of last year, wearing the solent. Recovering 19m2 of wet sail on a submersible deck with pressurised seawater pumping out around my ears cost me about 7 miles downwind, 2 broken fingernails and lots of lost bits of skin. I ended up beating, beaten and wet, into the shelter of St Mandrier, on the hook, to dry self and boat out and nurse my abrasions.
In explanation I sail single-handed and the eye-lashing parted due to UV degradation.
So in answer to your point - a heavy weather jib, on a roller reefer is probably a lot more practical than a storm jib.
We fitted a removable inner forestay this season. The boat is masthead rigged, and the new stay goes to within a foot of the forestay at the top. At deck level, we fitted a deck plate with a chain plate going onto the aft bulkead of the anchor locker. When not in use, the inner is stowed next to a cap shroud. This allows us to set it without runners.
Both storm jib (100 sq ft) and No 3 (~250 sq ft) were fitted with hanks. The 150% furling genoa is around 500 sq ft. There's no way we would attempt to drop the genoa in rising winds, so now we can just furl it away. If we're expecting any more than F4 to windward we set the inner stay and the No3. Have carried this up to 40knots AWS and she is a delight to handle with the main reefed down (have 3 reefs). We sail as fast as we would with a furled genoa, but point better with less weather helm.
I had adopted this arrangement for just occasional use, being no fan of partially furled genoas, but am surprised just how often we've used it this year. The boat is so well balanced that it makes her very sure-footed in bigger seas. Now thinking of fitting a second set of cars to make changeovers easier.
In rising winds I can set up the stay and hank on the sail ready to go, then only have to go to the mast to hoist and can then furl the genoa from the cockpit. Provided it is readied in good time, this saves the foredeck dance and I think it's the best compromise for us.
I have a removable inner forestay which goes to a U Bolt just aft of the forestay (huge ss plate behind so almost impossible to pull out)
the bottom of the inner forestay is in wire with wire block which clips onto the ubolt and then the very small storm jib hoists on itself and the spinnaker halyard is clipped on the head and it is sweated up.
Also have a 2nd set of blocks for the permanently attached storm gib sheets. Do not have to remove furling genny. pretty simple, fast and easy to set.
Only used very occaisonally when the **** really hits the fan. When it all gets too much for this I just pack it in and heave to.
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IRC Heavy weather jib
Hybrid Mode
