I have photos of M20 being modified with new bulkheads in the bow to take the jib loads. Plus a new order we placed with Goran specified the extra bulkheads.

2007 Texel really showed how much faster the sloop M20 was. and every distance race in Holland this year also showed how much faster a sloop M20 is.

Thanks for the info Macca, I probably need to check my source harder.....(setback!)

The sloop vs uni debate has been running a long time, and it's hard to get good data. We can of course start that thread again but we lack data to be able to say when and where the diferent rigs will will be better or not.

The only data that I found from the last Texel that could be used to determine the speed of different boats was an upwind leg, and on that leg the M20 uni was the fastest. Texel is quite a tricky race with several checkpoints you need to pass, I've tried it once in the M18. The first checkpoint is to get out from the beach and the we have this massive start, currents and so on.

You refer to several unnamed races in Holland where the M20 sloop "ruled", but I think you need to do more research before you use it as a fact. Who was sailing the M20 uni and who was sailing the M20 sloop? (The top guys in Holland prefers the sloop version and that will of course make the sloop to look faster....).

/hakan

It also has been decided a long time ago.

Afterall, Orange 2, B&Q and IDEC 2 were all sloops (as were all other record breakers) and that is not because the uni-rigs are better. The only records held by uni-rigs at this time are the 500 meter straight line dash, meaning the windsurfers. The 1 nautical mile record is held by Hydropthere and that is a sloop again.





The standard defense of the uni-rig sailors. Last time I checked, reaching the finishline requires the completion of at least a single downwind leg as well.

There are no prizes given for reaching the A-mark first.





And the sloops are not held back by this because ......... ?





Only a foolish boxer would claim the world championship after winning his first contest in a series of 7 prior loses.

And why can't you use a race around an Island to measure the performance of a sailing vessel ? Racing sailboats is not like a track event where everything is tightly controlled. Why should the course be adjusted to suit the design and not the other way around. If the uni-rig is King, shouldn't it be King in a wide variaty of situations ?

If not, then of what exactly is the uni-rig King ?

Wouter

with unlimited sail go sloop.. for limited sail go cat..

If sloops ruled completely both the "A" and "C" class would have remained sloop..

Do you know what these boats have in common?
Crossbow II
Sailboard
Yellow Pages Endeavour
Hobie Trifoiler
Sailrocket
Monofoil
Parliers Mediatis (60 foot catamaran)
C-class
A-class
...
They are all unirigs with or without sail area restrictions. Some of them have two or more sails but they do not work together like a main and jib.
The first Crossbow (proa) had main and jib and reached 32 knots, the second one, Crossbow 2 (cat), had one main sail on each hull and they where positioned to get clear air. Crossbow two reached 36 knots.

How many high speed boats uses main and jib?

Here's a list of the world speed records.
Outright record
48.7 knots Board (unirig)

8 m2 class
Board (unirig)

10m2 class
Board (unirig)

A-class
Longshot (unirig x 2)

B-class
Yellow Pages Endeavour (unirig)

C-class
Yellow Pages Endeavour (unirig)

D-class
Techniques Avancees (unirig x 2)

No sloops!?
/hakan

And what exactly is limiting the M32 sail area ?

I rest my case ! (after the next posting <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />)

Wouter

Yes, none of them have won a regular sailboat races or regattas.

Neither is any of these holding any sailing records at this time EXCEPT the 500 meter one-way dash.

Now if the M32 is intended to wait years for perfect conditions and sail in the French trench in order to reach the 50 knot barrier before any windsurfer does then it will have a glorious future I'm sure.

If is designed as a regatta boat then I think it has some marketing if not preformance problems.

Wouter

I already can smell a race in the air: Dutch F16 team challenging Canada in the C-class! Their secret weapon of hope: a jib!

Hopes die last, in contrast to jibs...

;-)

Well, if an F16 were to beat the most modern C-class then the uni-rigs really do have a serious problem, won't they ?

Why not much up an F16 against IDEC 2 ? Is that dissimilar enough for you ?

Ohh, yeah I forgot, IDEC 2 is also a sloop.

Hey ?!!!

Lets race an C-class against IDEC 2 across the oceans. That'll show the superiority of the uni-rig, I'm sure !


We all know it and have known it for centuries. Sloops outperform uni-rigs around a race course in all situation except the single situation where the sail area is so severly limited in overall area that it implicetly rules out jibs by definition.

That is like saying that the best boxer is the guy with only one arm as he won his matches against all other boxers who tied (at least) one arm to their backs.

Still doesn't say a damn thing about what happens when "the other" boxer can use both arms if he has them.


Hey, look how stupid Ellen Mac, Francis Joyon and Franck Camma are. They could have bested the round the world record much better if they had used a uni-rig ! Hell, any A-cat sailors could have told them that uni-rigs are so much more efficient that it is actually slower to try to break the records using a jib or, God forbid, that oversized jib called a "code O" or "screacher".

And those spinnakers, HAH !

Ever seen a spinnaker on a C-class or used in an A-class race ?

Surely this proofs that they are just useless pieces of cloth hanging out in front.

What more evidence do we need to confirm the fact that F18's never beat A-cats in a straight up course race.

If a spinnaker was in any way effective then the true innovators of the catamaran sailing scene, the A-cat sailors, would have invented, developped and incorporated it long before any other mortal would. The fact that they didn't is sufficient proof to its ineffectiveness.

If only we all pray to the A-cat God ! And stop our races after reaching the A-mark.

Wouter


Dirk, are you sailing an A-cat ? Because it sure doesn't look that way with that big green spinnaker out in front. I guess you are slower that way when sailing downwind then when sailing with only a mainsail (uni-rig) right ? Right ? I mean no C-class design is using spinnakers right ?

Matt and Gina, on their Blade F16 with jib, already have beaten several A cats, I-20's F-18's, boat for boat, around the same Windward-leeward course in the Alter Cup Area D eliminations at GYC in November.

Uni is fast in lighter air, but when it starts blowing and you need to depower the top of the sail, the boat with a jib can stay powered up in higher wind, due to the lower center of effort of the jib vs. the taller masts of the Uni rigs.

If you have a fixed sail area, I think putting some of that area in a jib vs. at the top of the mast makes more sense but only if you are out in more than 10-15 knots of wind. Below 10, it's probably faster to keep the sail area up top on the mast.

I know,

Actually what most fail to understand is that direct comparisons between sloops and uni-rig can easily be made inside the F16 class and actually have been made often as a result.

Basically choose your crew make-up and have one team (or skipper) sail with a jib and the other without it. Everything else stays exactly the same and can therefor be taken out of the equation. No sail against eachother and switch boats and do it again. On average you will come to one conclusion. Sloop is faster.


If think we did exactly this when you were over Tim. I was uni-rig with Gill and you were sloop rigged with Geert (and an underpowered Ullman mainsail. You guys would eventually overtake us on the upwind legs, no matter how hard Gill and I tried to defend our position and give you guys bad air. You guys just had more speed and as soon as you had passed us you would walk away.

We were sailing in what ? 10-12 knots that day ?





There is limit to how much area you can put in a mainsail, but you can ALWAYS add a 25-35% jib to any given mainsail. In very light airs the boat sails mainly of the top of its mainsail. The jib is not not helping much here, but it also isn't holding you back much. So when both tops of the mainsails are the same then in the light stuff the performance of the sloop is not too different to the uni-rig. When the wind picks up then the sloop will become significantly faster.

An excellent setup for record breaking. Very limited drawbacks while having frequently encountered significant speed advantages.

Wouter

Back to the M32, that boat is Uni rigged on the upwind and sloop on the downwind. In that way you get the high efficiency and low drag of a single wing on the upwind (like all speed machines seems to choose) and then switch to the high lift mode with the sloop configuration on the downwind.

The big problem for all beachcats during a distance race compared to the bigger multihulls are the speed gaps you have where you can't use the spi and you are not sailing high enough for double trapeze reaching. The bigger multihulls have screachers and other stuff that the smaller boat lacks. Here the sloop has an small advantage compared to the uni since it has two high lift modes to use, spi or jib which covers the gap a bit better than the uni. On the A-class with spi this gap is from 30-40 deg from downwind to about 70 deg from downwind where I can start to trapeze with main only.

/hakan

Ever time this claim is made without any regard for the fact that this is entirely based on a very selective reading of the situation.

I would most definately call boats that for example hold the 24-hour distance records as speed machines. Not a single one is a uni-rig here, neither any multihull or monohull in this respect.

It is also very "uninformed" to refer to the 500 meter distance record holders (all-out speed record holders) as upwind machines. None of these records are achieved on any course that even resembles an upwind course. As good as all courses used for waterborn speed runs are downright beam reaches or shy broad reaches.

Throwing in the windsurfers as proof against sloops is also a bit disingenious. Afterall, how would a windsurfer be fitted with a jib that has a tight leech ? The technical problems in this respect are far more effective in exclude any jib then any performance oriented considerations.

The simple fact that the sloop rigged Hydropthere is the current 1 nm speed record holder and a very serious contender for breaking the 50 knot barrier first is simply and totally ignored. Why isn't a windsurfer or a winged uni-rig like Yellowpages/Macquarie innovation holding this record ?

All my points made point back to the following observation. There is a group in sailing that has determine on some grounds that uni-rig are superiors to sloops (given any situation) and they are selectively finding proof for that believe while ignoring commonly available data that invalidates this believe.

Now, I'm not denying the properties of a uni-rig; I'm just highly critical of the intepretation, extrapolation and believes that are derived from these. These simply don't hold up to basic scientific discourse that demands that a given statement must hold under all "allowed" situations.

The claim that uni-rigs are more performant (speed) is so generally worded that is allows all possible situations as counterproof, and many counterexamples can be found this way. Ergo, this claim and similar ones are scientifically disproven and have been for many decades if not centuries

Sorry.

Wouter

Wouter:
In your side by side sloop v unirig in F-16 post (top of pg.4) is not the jib added area to the unirig main, i.e., the 2 boats have the same mainsail?

Is not the jib a high lift high drag leading edge device and subject to this article: http://aerodyn.org/HighLift/multi.html

I'm just trying to understand, and I thought this article applied in principal. I remember Randy Smyth pulling to shore and removing his jib in a Worrell when it was blowing hard and it helped. He won that leg, but of course there was a lot more going on.

And it seems to me Hakan is talking about a unirig w/ genaker setup vs sloop w/ genaker.

Also it seems to me that most of the vessels you cite cannot reasonably be used to establish anything relative to beach cats or even this M32. Hydroptere is a large hydroplaning cat, at least some if not many of the others are monohulls

Steve,




Indeed, both sailboats have the same size sail area. Note that is not cheating by giving one boat more total sail area then the other, even when indeed one but has more then the other.

The point of contest here in the M32 thread is about what is best for a new design performance wise. As it is a new design altogether, one can set its max sail area limit at ANY level. Of course their will be levels where not all sail area can be put in the mainsail, either practically or efficiently. With the F16's the mainsails are pretty much at the max area you can get in there while maintaining an acceptable aspect ratio (efficiency) and control.

Back to out topic. A completely new M32 design. The experiment that can be had with the F16's that relates to the M32's is this. Given the M32 the largest mainsail it can have efficiently or practically. That will be our uni-rig. Now make a second identical boat (same mainsail etc) but a 30% jib is added to the setup. Afterall, you can ALWAYS add a 30% jib to any conventional catamaran setup. Any problems that are encountered can be adressed by bridle foils and other simple solutions.

So the choice or rigs is not limited to either a sloop or uni-rig of the same overall area, but rather between a uni-rig and a sloop with 30% more sail area while using the same size mainsail.

It is this comparison that can be easily tested using F16's. As both setups, F16 and M32, are very similar in overal design the result can be expected to hold for both classes. In the F16 class we found the jib makes the boat faster, even on upwind legs. You point lower but move sufficiently faster to arrive at a higher VMG; and that is what everything is about. Brute force (=speed) winning out over efficiency (=pointing).




High lift yes, high drag not necessarily.

The thing to note about the sloop rig versus the uni-rig or even a rig consisting only of the jib is this :"When the two sails are set right relative to eachother, they mutually influence eachother in a positive way".

Because of the close proximity of the mainsail the jib is "supercharged" and is producing a whole lot more drive then this jib sail would produce without a second sail directly to its rear. Interestingly enough the jib will also operate at much smaller angles of attack while producing this disproportionally high drive forces because of the interaction with the mainsail. The mainsail itself produces less drive with a jib in front then when it would by its own, but the loses are smaller then the gains made by adding the jib. Also the flow of the mainsail is smoothed out and it is far less suseptable to stalling (losing attached flow). Its drive had become alot more dependable and it is easier to have it ride the groove constantly. This is the positive effect of the jib on the mainsail.

The net result is that significantly more drive is produced by a sloop rig (using same size mainsail) then a uni-rig whithout losing too much pointing. Actually the loss in efficiency per sq. meter and loss in pointing angle are overcompensated by the increase in speed due to having more sail drive. Ergo, the boat points lower with less efficiency per sq. meter but it still attains a better VMG and reaches the A-mark sooner on upwind legs.

In this role it is not to similar to the article you provided. It is however on course with high angles of attack. These course are reaching legs and broad reaching legs without spinnakers. Here the jib acts in much the same way as the slats and flaps of an aeroplane. These devises are used on a plane when the planes travells very slowly (landing / tak-off) and flies with large angles of attack. Here it needs to provide alot of lift without risking the wing stalling. This is similar to what a sail boat encounters on reaching and broad reaching legs. On these legs rig drag is not a major consideration as only a smaller portion of the total is acting along the centreline and limiting boat speed. The other portion is acting prependicular to the centreline and only loads up the daggerboards. The deeper you go the less rig drag is holding you back. Actually on a pure downwind leg it is actually the rig drag that is propelling you forward. So somewhere halveway there is a point were all rig drag is acting perpendicular to the course travelled and rig drag become an totally unimportant factor.

Here the jib makes the boat significantly faster then a pure uni-rig (no spi) by being able to produce maximal saildrive (30% more due to having 30% more area) at significantly larger angles of attack (= sailing deeper) while also delaying the stalling of the rig. Where some of these factors worked against one another on the upwind leg, limiting performance gains there, they are all working together to maximize performance on the other legs (reaching and broadreaching). On the pure downwind leg sail area is all sail drive is drag related here. Goosewinging the jib increases the area by 30% and results in 15% speed increase for that fact alone. Goosewinging is setting the jib to the other side of the boat then the mainsail is.




It should actually work the other way around in these windy conditions. A jib adds alot of drive low in the rig. Meaning it can add 30% drive for only 10% increase in heeling moment.
Do this mind experiment, Say both a uni-rig and sloop rig are 20% overpowered when sheeted tight. The uni-rig needs to loose 20% of the saildrive to stay upright. The sloop rig (with same mainsail) can remove the jib and 20% of saildrive and effectively become the uni-rig. But it can also depower the mainsail to 70% saildrive (30% loss) and use the addition 10% loss to gain back 30% drive through the jib, coming out at a 120% of the saildrive of the uni-rig.

Which one of the two do you think will be faster ?

An added drawback of the un-rig is that it depowers mostly by twisting off the leech and this impacts strongly on its pointing ability. So it looses both power and pointing by having to depower the rig. The sloop was already sailing lower then the uni-rig and the drive produced by the jib is totally UNAFFECTED by any mainsail leech twist. Basically the sloop can keep pointing the same as it was before while the uni-rig has to come down.





He is, but even in the setup we have found that a sloop F16 is faster upwind then a uni-rig F16 when sailed by the same crew.

Interestingly enough we also found that we need to add another person to the sloop F16 is bring it down to the uni-rig performance; this is reflected by the 1-up F16 (uni-rig) being just as fast around the course as the 2-up F16 (sloop).

Surely, having one person extra on board is a performance hit. The jib is the element that adds enough drive to speed the boat back up again.

This goes directly against the commonly "accepted" A-cat wisdom where jibs are regarded as nothing but trouble. Some even believe that adding a jib will actually make a boat slower. Of course these persons overlook the fact that there is no physical requirement to take the jib area out of the mainsail. You can always just keep the mainsail area and just add a jib (+ is area) to it (the total).

And this is where the M32 design will fall flat with respect to its competition, just as the M20 design does.





Longshot and the hobie trifoiler, as suggested by Hakan, are actually full foiling craft as well. The windsurfers being fully planing craft and the C-class cats use a solid wing as a sail.

Why can he make such comparisons between widely different craft to argue his case and I can't ?

I just showed the uselessness of his examples by producing similar counterexamples.


Having said all this I invited everybody to do their own experiments. It is very simple.

Get two identical sloop rigged boats and find a crew that has a similar skill level as yoruself. Remove the jib on one boat and race against one another in different conditions while swapping boats and possibly the sails. Your findings will most probably be that the sloop is faster, even when going upwind.

Ergo ADDING a jib (not cutting it out of the mainsail) makes a sailboat faster. So if you make a totally new design where you can set all limits yourself, will you decide to make it a un-rig or a sloop ? And that is the M32 & 100.000 Euro question.

Wouter


P.S. anybody wanting to read more about mainsail and jib interaction or looking for scientific sound proof; read the articles written by Arvel Gentry. He was the first to make his proof scientifically sound when the rest was still acting on "believes" and gut feelings.

wouter,

in most cases, adding sailarea makes a boat faster.

if you put that extra sailarea you propose to put into a small jib mounted low to the platform, into the mainsail (e.x. higher mast), I doubt the sloop will be faster than the uni in light air. light air is interesting because a boat and sail can be sailed to it's full potential. A and C class both allow you to sail with a jib, still even 60 kg light A cat sailors who might start pulling cunningham at 2bft are not doing it. in contrast 'heavy weather' boats like the F18 seriously struggle in light winds. If class restrictions would allow them to put the sailarea of the jib into the main (with a longer mast) my guess (no science) is it would perform better than the one with a jib till the moment the heeling moment can no longer be compensated by the rightning moment. by the nature of the rule the uni will be earlier overpowered than the sloop as it will be earlier lacking power in light airs. the reason why so many (succesful) boats and classes have jibs is to make them suitable for a wider range of conditions by giving up light air performance same time. I assume the AM2 catamarans on the Swiss lakes are a good example... their top mast gennaker are cut so flat they seemed to be usable upwind. saying this, if you want a good alrounder, a sloop offers a wider range (something you need on a RTW) while if you design for a particular small windrange, a uni wing will probably perform better.

by the way I would be highly worried if by my next step on an airplane I would notice jibs in front of the wings ;-)

You are right there Dirk and I have said so many times.

When the total sail area of a boat is limited to a rather low level, then putting everything in one sail is best. When it is not then "slotting" the rig and placing more canvas low is better.

My reasoning is only that limiting the total sailarea to such a low level is nothing more then an arbitrary choice.

There is no physical or technical reason to limit the total sail area to such low totals. Ergo there is no performance oriented reason to favour an uni-rig over a sloop rig for new designs/classes. And that links directly to my amazement about the M32.

Everytime the discussion hangs up on the CHOICE to limit the total sail area to very low totals. And every time I say something like; increase the sail area limit of the A-class to 20 sq.mtr. and see what happens then. I can garantee you that you will not see any uni-rig anymore.




What are slats and flaps then ?

Wouter

Slats and flaps are high lift devices (that asume you have good knowledge of) that you use when you have a high angle of attack, normaly during take-off and landing. If you would have the slats and flaps out when you fly with low angle of attack, which is the case during normal fligh, you would add drag. The drag must be quite high since all planes remove them during normal flight.

Now back to sailing!
A sloop always sail with a bit of flaps and slats out on the upwind where you have low angle of attack, but the uni can remove them completly during the upwind by taking down the spi. On the downwind where you have high angle of attack both the sloop and uni pulls out the high lift devices (the spi)

/hakan

I think you have a speed issue with that logic Hakan. My understanding is that you need to go at a certain speed before removing the slats/flaps pay off. Just look at a very specialized plane like the Fieseler Fi 156 ( http://en.wikipedia.org/wiki/Fieseler_Fi_156 ).
Sailboats dont move that fast really, and our airfoils are pretty high lift anyway. In my opinion the drag reduction of removing the jib in an unrated sailarea class will probably not pay off. But now we are back to the uni vs. sloop discussion we had just a couple of months ago. Like I said then, we simply dont have good numbers on the question, so we will not be able to close this discussion no matter how much logic we apply.

There is no need for any logic, just do the experiment for yourself everybody. Get two identical boats and removed the jib on one of them and see for yourself whether an ADDED jib is making you faster or holding you back.

When encountering a uni-rig believer, just ask him to place to largest possible mainsail on his boat and then go out and put a jib on there as well while keeping the mainsail and do again some on the water testing. He will huff and puff about maximally allowed sailarea and abruptly forget about any efficiency claims he made earlier. Of course you comply with his objections by fixing the maximally allowed sailarea to the total of the max size mainsail and jib combined. He will then only huff and puff indelligiaby and know he has been beaten.

Afterall, why does anybody have to agree to a such a low total sail area limit that it almost explicitly rules out the use of a jib ?

Nough said !

Wouter