Interesting question and even a very telling question at that.

If we were to do this then would the dominance of the uni-rig be proof of its superiority as a design concept or rather would it be proof of the class rules actively favouring this setup over the alternatives.

Or if the Moth class rules had forbidden the use of hydrofoils, would we then have seen proof of the superiority of the planing moths ?


I believe there are two situations that need to be kept well apart.

-1- The best design given a set of rules.
-2- The best design possible.

Wouter

I think this discussion is beside the point.

It doesn't really matter to the uni vs sloop debate what Goran intended to achieve with the M20.


I also think that olympic sports are mainly about one thing. To be the fastest, strongest or most agile sporter of them all. Using the best or best performaning gear is part of that line of thinking. I don't see many high jumpers reach back for timber poles because that will require more skill to achieve the same results. That is not something the spectators would understand or appreciate. I think it is the same with sailing. Part of the attraction is the fact that these sailors are sailing one the most performant designs available. That must be beyond question.

With respect to :



Basically the uni-rig is harder to sail well upwind, it is slower on a reach and on the spinnaker leg the difference is negligiable. When allowed to carry more sail area the sloop becomes faster upwind as well.

In the other aspects I don't see any significant difference.

I have to go to bad now.

Hi wouter
we have been here before ;-)



Without restrictions we would allwas end in a armsrace.
Look at the 12er skiffs. 3 Riggs and even more sails.

It depebends on conditions you are sailing.
If you have to stay with your chosen sailarea (gib and mainsail or mainsail only) through the whole season.
Then IMO the uni would be faster than the sloop in a broad range of conditions. I think i depends mostly on the seastate. In waves the taller rigg moves more and the airflow will detach. Otherwise IMO a proper trimmed uni will have less windage, will therefore be more efficient even when overpowerd.

Hello Andreas,

Here is my reply, All in good fun of course.




Well what would you call a 18500 Euro A-cat or a 35.000 euro M20 ?

Seems to me that the carbon uni-rigs are actually leading the arms race.

Also a full selftacking jib kit costs (ex. dealor profit) 1000 euro's, largely independent of its size. What I'm saying is; take any boat you want and then add a 1000 euro jib setup (possibly with a bridle foil setup) and get a faster and more alround boat. This can not be regarded as an arms race like making everything from carbon.


But sadly you make the same mistake again.



But what if this restricted total amount of sailarea is larger then what can realistically put into a single mainsail ? Will it then be faster to just get a smaller mainsail and simply forget about the remaining square meters ? Or will it be faster to used the excess cloth in a jib ?

Basically, my argument focusses not so much on having "no rules" or having "restricting rules" but rather on to what extend these rules activily favour one setup over another. Apparently, simply changing a single number can switch the favouring from one setup to another.


Lets take the 18HT class and raise its total allowed upwind sail area to 30 sq. meters. And of course we also take out the class rule that jibs are not allowed. Would we then still see uni-rigs in this class or would we see only sloop rigs ? Afterall, the game is about having the fastest boat, not about having the "most efficient" setup boat. While related, efficiency and "being fast" are not always the same. Sure the uni-rig 18HT with only a 20 - 23 sq. mtr. main will make the most efficient use of this (smaller) amount of area, but it will also be slower then the sloop 18HT that puts all of the allowed area to use.

So my thesis is : On what grounds are uni-rigs considered more efficient or, as sometimes claimed, superior ?

My conclusion is that they are when the class rules are written in such a way that they actively favour such a setup over the sloop rig.

The uni-rigs concept would only be superior in the large when it would still be faster then all other setup no matter what numbers are used in the class rules.

This situation is not academic. Think of landyachts. Here the uni-rig will always be faster because the very small angles of attack will prevent the EFFECTIVE use of jib no matter what the class rules say. Sailboats are still moving too slow and have angle of attacks of about 25 degrees when landyachts operate at about 10-15 degrees. This is the difference of doing 15 knots on a 45 degree upwind beat in 15 knots of wind or doing 25+ knots. The difference of 7-10 degrees is all that the jib needs to become effective. It is not certain beach cats will ever get up to the landyacht speeds and start favouring uni-rigs in the large.


So, you may not have thought this but while I absolutely favour sloop rigs on sailboats, I also favour uni-rigs on my landyachts.

Wouter

The arms race we are talking about is sail area NOT money.

The M20 platform can be sailed as sloop or uni. Lets compare the results from the different versions of M20 and see if Wouters formula works.

If we look at the times for the upwind leg at last Texel, the M20 without jib was faster than the sloop versions.

Round Texel 2006, the Uni rigged version of M20 came 1, 2. They smoked the Eagle cat on the upwind!

M20 participatet at Garda last weekend and was sailing upwind for 20 Nm in winds around 25 knots and they walked away from a top Tornado.

Do you see a trend Wouter??

LESS (sail area) IS MORE!!

/hakan

Håkan,

I dont have much to add to this discussion which have not been said already. But just out of curiosity, who sailed the M20 and who sailed the Tornado? Do you know how many M20s have been buildt? Do you know the cost of an M20 rig (just the rig)?

yes, and it includes Texel 2001, Texel 2002, Texel 2003, Texel 2004, Texel 2005, and what do you know Texel 2007 as well !

So you guys got lucky at Texel 2006. <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

O hell ! The results of all previous years must now be wrong !

Wouter

M20 was sailed by Marstrom and the Tornado was sailed by an Italian top team.

You can check the Marstrom web shop for prices for an M20 rig, the price was 3900 Euro ex VAT.

They have build around 20 boats, some of them are "Marstrom original" uni rigged with carbon rig, snail snuffer, internal spi halyard, cascading main sheet.

http://www.marstrom.com/

/hakan

Wouter we have the example you are looking for, add a jib and get a faster boat. But I can't see a real trend that the sloop version of M20 is "smoking" the Uni rigged, can you?

/hakan

So Wouter, what would you do ?

Uni at 100% mainsail or 75% main and 25% Jib ?????

Håkan,

Marstrøm gets about! The old man is really impressive.
The only time we have sailed tornados with him on the starting line he was a fair bit behind the olympic teams. Unless he has put in some more sailing time lately "walking away" from a top Tornado team would strongly indicate that the boat is quite a bit faster than the Tornado to windward.
Didn't know the italians had a top Tornado team going again after Athens. First italian team is in 17th position in the rankings followed by 25th and 60th. Not being ironic or "smart", just got curious and checked.

Thanks for the information about the M20. Sure will be interesting to follow the platform and the challengers in the years to come.

I talked to Goran today about the race and he called them a "top Tornado" team, and if they are among the 30 best Tornados in the world then they are good sailors. At the Tornado Eurpoeans in Sweden Goran wasn't even among the top 40, so the chances are big that the Tornado crew was "better" sailors than Marstrom.

/hakan

I think Wouter is reloading, time to put flame suit on and take cover.... <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

/hakan

That's funny.

Speaking of loaded; you'd have to be to afford one of these boats. Going a bit faster sure costs alot!

You are not listening Simon. I wrote my answer in the other posts already : "dependents on the total sail allowed"

I will sail a 13.85 sq. mtr A-cat as uni-rig and a 18.7 sq.mtr F16 as a sloop rig, BUT I would sail an A-cat with 18.7 sq. mtr as a sloop and a 13.85 sq. mtr F16 as a uni-rig.

I got a question for your as well.

Hobie 16, keeping the total sail area as it is, would you sail that as a uni-rig or a sloop rig ?

Wouter

No, you are not istening either.

I assume the reason you want to sail a 18.7 sqm A class is a sloop is because you feel that that size mainsail is too big on that platform.

So, you are saying that at the max size of mainsail that you feel is "right" you would always sail with the mainsail only option. But if forced to carry more sail than "right" then you would add it as jib.

Basically you are saying that as long as the "max sail size" is pitched at the "right" level, you feel that the Uni rig is more efficient

No, I'm saying that I favour the sloop rig unless the class rules are written such that they actively favour the uni-rig by limiting the total sailarea to a prohibitively small size (= wrong size).

A basic Prindle 16 has a larger mainsail then an A-cat and even as a sloop it is considered underpowered ! I sailed my P16 singlehanded as a sloop rig all the time, because it was indeed faster that way ! As every rating system confirms.

Argueing to move the jib area into the mainsail is mute as then I can always add a jib to that rig and be faster again. Basically, for any given platform a maxed out sloop rig will always be faster than a maxed out uni-rig; because it will always have 25 % more sail area. We have covered this before.

But knowing this, the more interesing question is indeed why the designer of a set of class rules would choose to enforce LESS sail area then can be had with a sloop rig ? The only reason for it would be that he actively tries to prevent the sloop rig from being used in this new class.

There may be valid reasons to do so, but gaining higher performance is not one of them.


Now we can play words games till we are blue in face but the neither the race data nor reality will be different as a result.

Wouter

Talking about race data :

Texel 2007

M20 GTI Pols (NL) / Veenstra (NL) 3:16:34
Volvo Extreme 20 Dercksen (NL) / Mcintosh (NZ) 3:22:25
Eagle 20 strabr large Straakenbroek (NL) / Vercouteren (NL) 3:23:51
M20 Flier (NL) / Deventer (NL) 3:25:45
eagle 20 XXL Bouscholte (NL) / Wieren (NL) 3:26:14
Tornado Samama (NL) / Leeuwen (NL) 3:26:54


And please note that these Eagle 20's are measured at 163 kg and 156 kg. Neither of them are the all carbon version. The Tornado is a 160 kg boat as well. So all the boats above have a significant weight disadvantage with respect to the M20 as well.

The Volvo Extreme 20 is basically a M20 platform with a sloop rig that is only 6% larger then the M20 rig. That is almost negligiable.

The M20 GTI has a 5 sq. mtr jib in addition to the original M20 mainsail and is therefor a pure 125% rig as discussed in the thread.

The "9 min/3 hour" difference between the M20 GTI and M20 is consistent with the 6 points rating difference due to adding a jib.

1 point is 36 seconds/hour. 3*6*36 = 648 secs = 10 min 48 sec (per 3 hours). And this is a horizon job; 3.5 km lead at 10 knots boatspeed.

We can all look up the weather conditions at this years Texel race, but with the lead boats taking 3.5 hours to complete there can not have been strong winds or a beam reach all the way.



Is this the "the example you are looking for" ?

Wouter

In this case.. The answer is what, roughtly 30 years old.
Given a set weight, sail area (but unlimited total scope), righting momentum, the boat would have a wing.
Miss Nylex showed the way..

When we discussed the last Texel we agreed on that it was ratcher messy race, most of them are, with restarts and so on. But we found one leg interesting, a pure upwind leg, and I checked the times there for the top boats and M20 had the best time, not by much. On the upwind "less is more"!

A fully powered up uni rigg WILL NOT GO FASTER if you add even more sail area with a jib ON THE UPWIND.

For a "normal" Texel race where you reach a lot the jib will make the boat faster. If the Texel rating is tuned against round texel then it makes sense that adding a jib makes it faster, but it may need some reworking for upwind/downwind racing in that case.

A uni rigg with spi is a pure upwind/downwind machine and has a lot of speed gaps when you are deviating for the pure upwind/downwind course. I have a lot of problems with that when I sail distance racing with the A-class with spin.

So are we talking about upwind/downwind performance or sailing around an island performance in this thread?

/hakan