Most of you are skeptical about F18HT cats.
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<br>Someone wrote on the Old Forum: " A cat only 8' wide with no jib and a 204 sqft main seems a little underpowered and too narrow".
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<br>I understand this opinion.
<br>We all are accostomed to the heavy and overpowered boats produced so far by the biggest boatyards, so that we consider a non-sense a 18' cat with less than 21 sqm of sail upwind (AND NO JIB!!!).
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<br>Anyway yr "UNDERPOWERED" F18HT is faster than any other 20 footer both upwind and downwind up to Force 3-4. In Force 5 + perhaps only 10' wide cats (like the Tornado) have a slight edge. The INTER 20, HOBIE FOX, NACRA 6.0 etc. are slower in all conditions than F18HT cats.
<br>The reason:
<br>LESS WEIGHT (110-130 lbs), LESS POWER (204 sqft against 225-245 sqft), MORE EFFICIENCY (UNIRIG vs SLOOP - higher aspect sailplan/32' vs 29.5' tall mast)
<br>Maurizio <br><br>

Maurizio,



I agree with alot but please, we shouldn't over do it. Or make it into more than it really is.



>>Anyway yr "UNDERPOWERED" F18HT is faster than any other 20 footer both upwind and downwind up to Force 3-4.



I would like to distance myself (and the F16HP class with it) from claims like this. A US I-20 has nearly the same mainsail as the F18 HT and is equally high and together with the slot effect the I-20 rig will produce more power than is proportional than it's increased draq. Ergo it has a better power to drag ratio.



Now I might accept downwind but not upwind. Simply because in a few examples the numbers just don't add up.



>>>The INTER 20, HOBIE FOX, NACRA 6.0 etc. are slower in all conditions than F18HT cats.



This is a tough claim. And I don't think that the situation is that clear cut. But time will tell.



>>The reason:

LESS WEIGHT (110-130 lbs), LESS POWER (204 sqft against 225-245 sqft), MORE EFFICIENCY (UNIRIG vs SLOOP - higher aspect sailplan/32' vs 29.5' tall mast)



More efficient ? This is very simple to say but equaly hard to proof scientifically. I can assure you that efficiency in this respect is very dependend on conditions. A sloop in higher winds of equal or little less overall sail area can well produce more thrust than a high masted uni rig that is depowered under the same conditions.



These numbers and remarkable meteological phenomenons favour the F18HT heavily in winds up to 5 kns as well as any other high masted rig. But right from 6 kns and up the advantage has been cut down to just a few % ; this is without depowering, when the rigs get depowered the sloop will close the cap even more and even overtake the uni rig in total produced power.



These numbers do explain the F18 to iF20 experiences in the medd to high winds so why shouldn't they cover the F18 HT.



Now saying that the F18 HT is much faster than all others can do us far more damage than we want inflict on this new lightweight classes. So please, do not overstate the performance.



Once again, F16 HP class does not support these claims and my models who have been used to develop this clear don't do so either.



Wouter

Wouter,

I do not want to follow you in yr math models.

On the contrary if you like i can provide you with many regatta's results, DEMONSTRATING what I stated, that is the F18HT cats won on elapsed time many open events both round the buoys and long distance, both on the sea and internal waters, beating all 20' cats including Tornados. Perhaps they did not win olny Texel.

Maurizio

Please do maurizio ! And I want the conditions listed too and I'm going to look them up on the net.



Nobody is benefitted by claims that can not be substantiated so I think you should do this.



I'm very amused by this sudden discovery of the all time greatest catamaran but till now I can only say that it had a all together negative effect.



And it will kill us off when these claims are debunked.



Now I can show some results that a 16 footer beat 20 footers this 2001 season but notice that I DON"T claim that this cat can do so on a regular basis.



Wouter

A Nacra 6.0 NA carries around 265 ft^2 sail upwind and a 350-500 ft spinnakers of the wind. The boat weighs around 430 lbs with spinnaker equipment is 8.5 ft wide and has a 31.5 ft tall mast.

With a min weight crew you have 755 lbs total weight

At present, we don't have any 18ht boats to compare it to in the US, however in my experiance a nacra 6.0 and an A-cat are about the same speed around the buoy's (both non spinnaker)



Having sailed against a very well sailed model, the Marstrom M 20 is much faster then a Nacra 6.0 under all the conditions I have seen.

The CFR 20 is faster upwind/downwind, but not reaching.



Why don't you compare and contrast the sail area to displacement sail carying power to displacement and the wetted surface (estimate) to sail area. Of these two boats. Acording to Bethweite SP? these are the more relavent indicators of a boats speed potential.



Eric

Wouter

I found some results on the web, but only the most recent. As you know after a while every web pages fell down. Some others thanks to the International F 18HT class Association. However none of them are complete as you want: they do not state wind conditions, elapsed times etc. So they are not probationary from yr point of view. Typically they provide only the general classement.

Maurizio

I would like the data anyway M. I can also use data as input to fine tune the models.



Wouter