Rick - I assumed all along that this would pull in the souped up Wave you've been sailing. You fit the box, so bring it on!

I want to get Blade or 4.3 T plans and build.

Going to use an A-class main, cut down to fit a 24' mast.
I'd like to get some pictures of the ARC boats, particularly the decks. And a LOOOONG pole w/chute.
8'6" beam to fit a trailer I've already got.

In response to Steve Kwicksilver
"Pick a PN number that is a little ambitious for a 14ft boat, but not so wild that you have to modify the hell out of a boat, or overdesign the rig to be competitive. Base it on the average of the 14ft designs that you have sailing currently with added spinnaker / hooter. Good idea to base it on that H14 that is on steroids."


It is a good idea except you can't calculate a Portsmouth # to that level of detail. A Portsmouth corrector can tell you the effect on a boats Portsmouth # of putting a spin on or widening the beam. There is no way of calculating what you have to do to a Mystere 4.3 to make it equal to Bob's H14, for example. I don't know of a way to independently calculate the Portsmouth # of a totally new boat.

The texel system claims to be able to do that. BUT, it has known problems with light boats and it doesn't rate a hooter equal to a spin. There are probably other problems that I don't know about.

IF EVERYBODY AGREES THAT:

1) all of us are sailing light boats so the problem will be EQUAL FOR ALL OF US

2) A hooter and a spin are equal on a sq foot basis (i,e, a 100 sq ft Spin is the equal of a 100 sq ft hooter)

3) Foils (dagger boards and rudders) are NOT taken into account

4) a maximum mast height and all masts are equal

5) Plus some other things I have not thought of


You could generate a CRUDE table that would give you max upwind and downwind sail area for a given length, width and beam.

For example, you would round your length and beam up to the nearest 3 in, round your boat weight up to the nearest 10 lbs, find these values in the table and read off your max upwind and downwind sail area.

You would probably find a Wave would be allowed to run a spin hanging from a helium balloon in addition to a hooter.and still be below max sail area

Any better ideas and who wants to generate the table? I will help but right now I am real busy.

This class sounds great. I have too many boats already but it will be fun to watch. Just a thought from an interested observer:

8'6" beam can be a pain on the road and in transit. A-class are 7'6" I believe. and I don't think you would miss the beam on a 14' boat.

IMHO

HuntS- Are you from Europe? Most of the sailors in this debate are in the US where we've got nice wide roads and all the 16'+ cats built in the last 15-20 years have been 8'6" wide.

As mentioned above- if we're having trouble with the boat being two wide, a chopsaw and a drill can fix it. Much more difficult to fix a boat that's too narrow.

The F-16 ht Class and web site did a very nice job of comparing different design variations within Formula classification by using Texel and ISAF rating -
They only take basics of L B W SA plus a few other factors in the design measurement rating to arrive at an average comparison of all types of cats ,--but that is very different from a detailed design annalysis in greater depth on similar designs in a similar classification .

It is ISAF that provides the basic definitions and standard methods of measurement that is the basic language used when defining these types of design measurement based formula classes .-
http://www.schrs.com/schrsdiagrams.asp?id=boat

A detailed design annalysis is not needed ,-no one would agree on its method or relative numeric value placed on numerous varied design features which would then vary in each wind and sea condition .

Think your correct that all must agree in principle that all boat types have a reasonable opportunity to modify their boat to potentially be the equal of any other .

check out the F-16 site ,-and its ISAF conparison
plus a really nice basic box rule diagram with basic specs of L B W sail area etc
http://www.geocities.com/F16HPclass/
when you have time

good luck with the F-14 building project
sounds really interesting .

best regards

Carl and others,

Over the years a new measurement based system was worked out. (Carl didn't so I did); It works in a similar way as ISAF and Texel but adresses the problem points of both these systems. Problem points like : light-heavy wind shift, sloop rig cat rigged after adding a spinnaker. Singlehanding versus doublehanding.

This system is currently code named "New Measurement Based Ratings"

The latter system may well function satisfactory in the role proposed by Carl if any of you want to go that way (which I think to be unlikely)

Never the less I wanted to make you aware of the new possibility.

This forum doesn't allow me to post the working excelsheet + tabled input and resulting ratings so any body interested just has to mail me and I will send it to you.

Wouter

Way to go Wout , it furthers efforts to understand design and helps establish F-type classes -sounds good .

Think the ISAF or Texel are just for quick comparison purposes ,--but not to base a F class on . They should just be used as a snapshot ,-much like a Pn # - and hopefully be within 2 points or so of each other in class when comparing different brand types once modified to max class specs. ,--If not then examine why , often its a clitch in the particular rating system that can only average out numerous vastly different design features --boards to non board types --hi aspect sail plans to low --very heavy to min ht types --etc .

In examining the same types of very similar theoretic designs in a class definition you could actually use existing design software than would examine and compare in great detail the numerous specifics of design and calc. theoretic speed potential in each windspeed then average those in a mid range ---but still an average that varies greatly in conditions ,--also greatly mainly with human ability and other intangables like specialized sailing techniques developed by racing sailors not considered by the programer or designer .--
example --on I 20s many teams will center the rotator on the CF mast w spin up going downwind ,--the rig flexes much more in gusts creating a pumping type action that accellerates faster . This is just one of many , also learning to tune a boat for varied conditions makes huge differences on the race course and in theoretic speed .
how can any equate that?
Any rating "system" is imperfect and an average to some extent .
That is why CLASS racing is the ideal ,-and Formula the best means of including all within a basic box class category .
Concluded that and thought it better to work within ISAF or Texel and just promote Formula type clases .-

A detailed design annalysis would include such comparisons as hull design and form drag with frictional area drag .
Calc the area of wetted surface both static and under various wind strengths and degrees of heel ,-and in seas .The prismatic coeficient ratio of various hull shapes . Volume calc , section comparison ,-stern design and form drag annalysis , then the foils -boards rudders -
hull finish. -weight distribution -moments etc -on to the mast sail plan etc etc etc . It is a very lengthy process full of condition variables compounded by an infinite number of combination design features and new innovation and design add.

It is a fun endeavor , and such a great sport , hope all enjoy the process and appreciate the people involved .

It is a little simpler than that Carl !

Wouter

An unlimited beam width for a catamaran is fine BUT, the wider the hulls are apart, (assuming the fore and aft position of the mast step position is kept the same), the more prone the cat is to pitch poling due to the increased sail dynamicly generated down ward pressures transfered to the bows. In fact, rather than achieving a more stable base by widening the distance between the hulls, the reverse is always the outcome when the ideal ratio between hull beam, hull waterline length, mast hieght, sail area, and aspect ratio of sails, is exceeded. A very rough "laymans" measurement for this is approx 14' length, 7' beam, upto 25'6" mast hieght, and an approximate sail area of 130 sq ft (depending on the aspect ratio, the lower the aspect ratio the larger the controlable -with advantage- sail area that can be carried. The use of a spinnaker falls outside these dimensions as all sorts of dynamic changes occur to the controlability of the boat with the kite, all of which are able to be comfortably incorporated on the same cat.

Who says the mast and hull positions are staying the same?