Ok, I'm talking about mainly light to very light air in North American summer sailing. Some impressive boats like theM20 (Goran says you don't need a jib, but he doesn't sail here) and F18ht don't have jibs. Logic seems to indicate that with a high aspect main and spin you really don't need a jib. Of course the jib helps turn the boat quickly, but that can be overcome with improved technique. And it has been proven repeatedly by A-cats and others that the jib doesn't get you upwind any faster in most conditions. I say MOST conditions. My observation is that in light to very light wind the jib not only helps read the wind (see other post) but makes a big difference in speed. Much more than its area would suggest. I read that the I-20 substantially outperformed the f 18ht in light air (less than 5kt?) and I don't think it is just because of more sail area. They have a LOT more weight, which usually kills light air performance. I hate to pose such a subjective question, but I would like some indication that either my sailing technique needs a quantum leap in improvement, or that a jib is more than a crutch, at least in light air.

If you only sail windward/leward courses, a high aspect main and a spin are all you need. Throw in a reaching mark and, in my experience, the boats with large jibs do a lot better.

In the places where I sail, light winds are also very shifty. In those conditions I can't see how you could use a spinnaker. First of all, there's often not enough air to fill the spin, and secondly they're too hard to control when your point of sail can go from upwind to downwind several times on the way to a mark. A hooter or screacher would do a lot better in those conditions.

If you can't use the spinnaker effectively, an Inter 20 should be a good bit faster than an F-18 based on sail area to weight ratio. Just counting main and jib, the Nacra F-18 has 220 ft^2 of sail area and is 385 lbs. The I-20 has 246 ft^2 of sail area and is 390 lbs.

I disagree with you that area in the jib is better than area in the main in very light air. Among the group I sail with, the dominant boats in very light air are an A-cat, and my own. I've got a 5.8 with a heavy dacron square-top with lots of shape. That sail will pull me forward even when the jib is limp and lifeless.

Yes, it is me again. (joke)

for some reason I've been very interested in the jib sail for some time now as its behavious determined its future in a specific class in which I'm involved. Some will call the following remarks spin others propaganda, some will read them and take the info that they are interested in. I hope you are the last kind.

But first a jab under the belt to Goran.

>>Some impressive boats like theM20 (Goran says you don't need a jib, but he doesn't sail here)

Well that M20 still has a whole lot of problems finishing ahead of Gorans own tornado designs which, as we all know, is a sloop rigged catamaran of 50 kg more weight. And I'm talking elapsed time results. And don't get me started on that other design now that the Tybee 500 has proven to be so insightful.


>>Ok, I'm talking about mainly light to very light air in North American summer sailing.

Roger that. Ehh, lets not forget that in these condition waterline length is NOT important anymore (better measure would be prismatic ratio but we'll just forget about that). Only thing that is important here from A-cat to nacra 6.0 is wetted surface area and its related friction drag. It is absolutely possible that a heavier shorter hulled boat has less wetted area than a lighter longer one like the M20 for example. So when the rigs are comparable than a shorter heavier boat can been seen to be in front against "common sense".

>>Logic seems to indicate that with a high aspect main and spin you really don't need a jib.

Well that is true to some extend. Is is always more difficult to trim a boat well without a jib as some are finding out now. Also the spinnaker can not be flown always as another poster has indicated. If it doesn't fill than the spi is only an item that introduces extra drag. But in most conditions the spi will make it easier to sail well downwind as she will replace the jib trimming function. Even the A-catters will tell you that downwind sailing with only a FULLY battened main is the most difficult part. In light air the battens make the sail riggid and it hardly reacts to chanhes in trim. On say laser 1 you can tell sail by looking at the luff of the mainsail curving in but the battens on teh cat sails prevent this.


>>Of course the jib helps turn the boat quickly, but that can be overcome with improved technique.

Indeed, besides using the jib to turn is like putting the breaks on to make the corner, it slows you down. With proper technic the jib is not needed and the speed of your tacks improof to such an extend that you just the jib over and nothing more. Rolltacking is an important technic to learn here; especially in light winds. ALSO you must move gently and only when you have to.Sitting still on the boat and wait makes each boat go faster and faster with each passing second.


>>And it has been proven repeatedly by A-cats and others that the jib doesn't get you upwind any faster in most conditions.

Not this is simply not true. The people who say these thigns are comparing A-cats to some other completely uncomparable design and concluding that it must the absense of the jib that causes the difference. This is just BS.

What any zealot of the "Jibs don;t make you faster" theme should do is pick a sloop rigged boat; arrange for two of them on the water and race them against one-another where one boat has no jib. WITH FULL COMPLEMENT OF CREW of course.

Example : get two I-20's or two H20's and get two equal crews, remove the jib on one of the boats and correct the mast rake accordingly. I can tell you that that boat with the jib beats the jibless one EVEN on upwind legs.

Of course now starts the screaming. "But you've got more sail area !" Yes of course, that is the charactertic of sloop rigs; they allow more area to be carried than when without a jib. And I think that you ,Steve, don't two mains of different size (You are sailing the FX right?). One for its sloop rig and one for its uni-rig setup. So in Steves case, the A-cat setup does not entlighten us to HIS choice between "just the main" or "the same main with a jib". I figure that you are not cutting down on you main when you fit the jib, are you ?

So in this case (and that of other sloop rigged boats that can be sailed singlehandedly in both the sloop and cat rigged setup) the fact that the jib increases the overall area of the rig significantly can make the sloop rig faster upwind than the same rig but without the jib.



>>>I say MOST conditions. My observation is that in light to very light wind the jib not only helps read the wind (see other post) but makes a big difference in speed.

Bigger overall area and that fact that you can get the sloop rig to be dailed in for much longer periods than the cat rig make the sloop rig feel more powerful and more forgiving. This is my experience in this design too as well as on other designs. Maybe the catrigged setup that is achieved by leaving of he jib of an otherwise sloop rigged design may be slower and feel slower as a result of these points rather than you sailing skill.


>>Much more than its area would suggest.

Well, Bethwaite had indeed some insightfull things to say about how the jib acts together with the main. One the more striking things was that he and others liek Arvil Gentry found that it is not the jib which makes the main more powerful but rather that it is the main that make the jib more powerfull. The ventury effect has been put to rest and a new theory with much the same overall result (more power in the rig than you would expect) is coined. But Personally I think that its usefulness in setting and maintaining the optimal trim plays a very large part in the light winds we are talking about here.


>>>I read that the I-20 substantially outperformed the f 18ht in light air (less than 5kt?) and I don't think it is just because of more sail area. They have a LOT more weight, which usually kills light air performance. I hate to pose such a subjective question, but I would like some indication that either my sailing technique needs a quantum leap in improvement, or that a jib is more than a crutch, at least in light air.


Again, MY PERSONAL OPINION is that the jib makes the basically sloop rigged design feel more powerful and feel faster. It is also my opinion that they are faster too in light airs unless the catrigged sailors is really skilled in achieving and maintaining optimal sailtrim of this rig. The last thing takes alot of experience and is mostly done by the feel of the boat. It is my opinion that it is very easy to sail out of the optimal trim on a catrigged boat in light winds. On sloop rigged you see little warning signs when this happens like the luffing of the jib and thus can react much sooner and more adequately to the changing conditions/trim.

I have however no doubt that a uni or cat rigged boat is more efficient in light airs for a GIVEN TOTAL AREA and that it should be faster upwind as a result. However this efficiency only "works" in the period when the rig is optimally trimmed and this trim is maintained. See it like this a 25 % more efficient rig (say 100 %) that is only efficient in 50 % of the time WILL loose from a reference efficient rig (say 80 %) that is kept working for (only) 63 % of the time or more.

Notice how small the difference in "dailed in" time is ? And more strikingly this difference DECREASE when the cat with the efficient rig is less capable in keeping it efficient.

For novices to medium skilled sailors the time that the rig is set optimally in light airs is so small that sloop rigs easily can outperform cat rig setups by having better "engaged time ratios). Ratios of "50 % of the time properly dialed in" are pretty high in light air for normal sailors. OF course the top sailors achieve higher ratios and here the more efficient rigs will start to excel. When the total areas are the same of course. When the sloop rig has more sailarea as well than it dependents on the sailarea's wether the catrig will be faster or not.

Once again "there is no free lunch"

I personally liked the FX with a jib better in all conditions. I thought is was a better balanced boat like that and it felt more powerfull. Some of us in the class where I'm involved in are looking into "super-slooping" as their singlehanded setup. I think I will go along with that and fit a selftacker to make it easy on me. The past year I have competed in the clubchampionship with my "superslooped" Prindle 16 and the experiences there comformed all my believes.

Wouter

My Nacra 5.5 Uni was faster upwind than the Nacra 5.5 SL and sailed a higher angle - by far. That was with one person on each boat. We had four 5.5 SLs sail against two carbon unis. The unis tacked faster, got up to speed faster, sailed higher, and the same or faster upwind speed. Downwind the SLs were slightly faster.

Reaching is were the unis don't do as well as the sloops.

I wish I had more time to discuss. I have a Taipan 4.9 that I sail uni, sloop, and both with spinnaker that I can give info on later. Got to get to bed now.

I'm new at sailing cat rigged and always used the jib as a bit of a "crutch" to help trim and steer upwind. I have been trying to learn to sail cat rigged on my new Taipan. It points very well in light air, but I find I need to sheet a lot less than I think to get good airflow, keeping plenty of twist and camber in the main. Anyway, in light air I can make better VMG with the jib than without.

But here's my real comment. Sure, as Pete said the jib really helps reaching. Well, in light air, I've been sailing cat-rigged with the spinnaker. I reach with the spinnaker and this seems to be very fast. Spinnakers we use are, of course, really gennakers; ie they are very flat. If I sheet the spinnaker hard, I can reach fairly high in light winds. Your real question is about light air, right. As the breeze picks up I have to sail deeper with the spinnaker to keep from capsizing. Recently I found myself in 2-5mph wind conditions. I was amazed at how fast I could beam reach with the spinnaker, even flying a hull at times. I have not done two boat testing, but it is hard for me to imagine eecking nearly as much speed out of those conditions reaching with a jib.

Hi Steve, Fellows,

(In this post I'm talking: strictly upwind in non-overpowered conditions)

I have followed the previous thread and I think that Rob offered up a very good suggestion on technique, over at Rob's post on how to sail a unirig. And I would say that you might need to move your tell tales (add some) aft enough to avoid the turbulent area that you suggested is fouling the tell tales in that wing mast to canvas sail interface. (Well at least the lee side. Don't expect too much result on the windward side in such a deep chord) Also, I concour with the others that you do need to keep an eye on the leech tell tales.

But you seem reluctant to lose the jib in light air. And you seem to wonder why you are not able to do better without it. Could it be that the sail area to weight ratio is just at a better balance when you have both sails flying? I don't know the sail areas of the boats you metion, but just for instance; is your main sail area to all up weight ratio close to that of the F18HT with its super tall mast?

From my experience, the sloop rig is far more forgiving. This allows the sailor to stay in and quickly return to the "sweet spot" or "groove." If you are able to keep the sail trimmed to the apparant wind speed and apparant wind angle when faced with the challenges of true wind's changes of velocity and direction as well as the effects of water's chop, waves, and currents, then the unirig is great. But to repeatedly power through these challenges without seriously falling out of the groove requires some pretty quick handiwork compared to the wider slot that you have when sailing sloop rigged.

In light air I want my jib. I don't want to be without the extra sail area it provides, unless I am overpowered or moving so fast that the drag it produces is a harmful factor. But in medium air I can do it either way, with or without the jib.

Since I was more trained with the jib, and since the rig has a narrower sweet spot when in uni mode, sailing in sloop mode is far easier. Sailing in unirig configuration offers a narrower and faster groove. It requires more concentration and sometimes requires radical changes in trim or helm to react to such confrontations as waves and wakes. As I practice it more, it becomes less foreign when compared to sailing in the usual sloop riged configuration.

I consider the sloop rig to be one combination of sails which work in concert and whose net result is to behave as one large unit.

The jib does accelerate the flow on the low pressure side of the main. This allows the main to produce amplification of the jib's action. This allows the Main to do more work than what the main can do by itself. But the net result of both sails still can add up to one resultant that behaves like one larger sail and this is how I think of it:

Let's say you need to alter your foil (main sail on a unirig) to reduce drag and lift; you want to go faster and have the available (prevailing, or developed/apparant) wind speed to jsutify it. You flatten the draft and (and/or) lengten the chord. You have several methods to do some of it and if you use all of the methods in concert, you flatten even more so.

So you increase the outhaul to stretch the length of the chord as well as decreading the draft. You increase the down haul to lengthen the chord by moving the luff farther from the leech and, flatten the draft by spreading the same amount of sailcloth over a longer distance fore-aft. Sheet in, not only to produce twist and reduce the attack angle, but to also induce more mast bend and add to the same results as increasing the down haul. You might even decrease the mast rotation to extend the length of the cord and reduce the attack cross sectional area of the wing mast to match the now recuced chord of the sail. There, you've made the unit (one sail in this case) longer and flatter.

You've used four adjustments. The mast roation and main sheet were used to alter the attack angle. The main sheet was also used, in combination with the down haul to lenghten the chord and shoal the draft. The outhaul lengthened the draft and shallowed the draft too.

Now consider a sloop rig, as a lifting foil unit. Want to flatten and lengthen? With the jib luff tension you flatten the leading edge. With the jib sheet tension you flatten the forward portion of the foot. The main outhaul does the aft portion of the foot of the entire unit (jib and main in combination to make up one large foil)

The jib is sort of acting like the leading wing protrusions on an aircraft wing (ailerons?). The main sail's outhaul is relative to the trailing edges of an airplane's wing (slats or flaps?).

By the time the wind has passed all around the lee side of the entire unit, this can interpret into a very large draft..and a very large chord. It is a pretty drafty unit.

My terminology is week, but my point here is that the entire lifting surface that is the combined effort of two sails working as one unit has more control surfaces to adjust. This can be thought of as sailing in a lower gear.

When in a low gear on a machine or most any kind, you can more readily and subtley change the output with your input, even if you are slow to react to changes. But in a high gear you can make more drastic changes if and only if you can react and respond at the proper time. Or else, you will fall out of the groove (fall out of the torque band or horse power band before you are able to fully and adequately adjust to the changes).

I'm drifting and I know it is time to stop for now. I hope when I come back to proof read this that it will make sense.

Too bad that the editing feature on this forum does not allow you to change, tune, correct your posts if you wait more than a few minutes to review them.

But one more thing: As long as your CE is properly situated, tacking a unirig does not have to be too difficult. Your tack angle should be smaller than if you were sailing sloop. And your boat speed in the water (read that as lift on rudders) should be faster, while closer to the wind. So your tack should happen quicker and easier when you consider that you are not pushing that jib cloth through the eye of the wind and your main sail will be powered up and working sooner than if it was trimmed for sailing at a deeper angle.

GARY

Gary said it right,

The only issue with tacking a uni-rigged, even when applying the right technic, it that they have a little more tendency to wind back up into the wind when you pull on the mainsheet to soon. Once this happens you are pretty much lost; you'll be losing many places and alot of time by backing up and pushing the boat to one side. I found this tendencie especially menacing during mark roundings where dirty air of other boats makes tacking more unpredictable.

Of course it it better to make a less optimal tack than to blow a tack. Therefor I let my platform rotate a little further of the wind than is strictly required IN LIGHT AIR. Now I only slowly pull in the mainsheet and keep the angle of my rudders small. The boat slowly picks up speed and now you can pull in more tight as you have full action of your rudders. The 3 seconds or so you loose on this wide manouvre is often neglectable. Especially in light air crews all over the place are blowing tack. You also blow a tack when you accelerate out of one very very slow. This may feel like succesful tack but loses more than the 3 sec you will have lost.

In stronger winds, this is not an issue. Here I allow the boat to turn to its new angle or just past it and sheet out some when the boat has turned through the wind. This outsheet main will accelerate the boat initially without rounding it up a lot. Then when you have speed you sheet in and get the full acceleration.

Wouter