Bill,

Is this good looking enough ?





Indeed the sail just slides on.

Thanks for answering that question for me, Bob

Saves me time.



Wouter

Wouter - Yes it does.

While probably not important from a performance perspective, the material does lend itself well to hot graphics - just the stuff kids are looking for!!! <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

Thanks for the picture,
Bill

Bill

wouter

Nice!!!

This is where I thought (hoped) you were going with the design of the rig. Modern looks and easy to install.

Thanks for the visual.

You might want to check out these sails. This particular site will show the progression of Ezzy Windsurfing sails from 1994 to 2007...the newer sails have a much "cooler look" as well as superior performance. http://www.ezzy.com/2006/sails/rig_guides.cfm

Regards,
Bob

Well what is F12 refering to then? One could only assume that F12 meant 12ft, F14 meant 14ft, F16 meant 16ft and f18 meant 18ft.

So maybe I should wait then til we work out what the 12 means, 12ft, 12 years or older, only sailed after 12.

I apologise then, I'll wait til you tell us how long the F12 is going to be.

Regards

Matt,


The F18 is longer then 18 feet. (by almost 2 inches)

The F16 is longer then 16 feet. (by 5 inches)

Hell, even the F20 was longer then 20 feet. (by an inch)

We'll have to ask Darryl Barret about how long the F14 TRULY is.

Agreed the proposed F12 is longer then 12 feet by 10 inches and thus relatively more then the others but still it won't be the odd one out.




Again, what are you exactly trying to say here.


Wouter

Matt,

I know the original intent was to build a class of boats 12 feet long for kids. However, it seems that there are some benefits in making it slightly larger which seems to make sense.

The only downside to making it slightly longer is definitional (Is it an F12 or F13?). If a strict definition were used in naming the class, what are the stakes or issues in calling the class an F12 or an F13?

Thanks!
Bill

Bill & Matt,

I agree the name is purely semantics, or has evolved to that point. I think tying this boat to the most current (developmental) and popular Formula catamaran classes, through it's name, (and class structure) is an opportunity to lend stabilty and flow of sailors to the larger boats. Not to say that any other boat (PT, arufa) can't do the same thing.

The H20 is 19.5 and H16 is 16.58, we're splitting hairs here. Issues? Can't think of any real issues.

F13 is not a good choice for name, IMO.

I won't consider the name F13 for as long as whole societies refuse to have a 13th floor in high rise buildings.

Wouter

and Wouter asked to make a choice, and reasoning behind our choice, of 3.66, 3.90 or 4.00

Will the water line length of the F12 be equal to its length overall? Waterline length is commonly used by some power boats to define length…On the huge SKA circuit (Southern Kingfishing Association) they have a 23’ and under class…but it goes by waterline length, not length overall…so some of the hulls end up being well over 26’ even though they are called the 23’ and under class.

If the bow of the F12 were a bit more sloped back aka “wave piercing” and had a transom that slopes forward, maybe you could steal a few inches of increased length where it counts, underwater. If somehow the "loaded" (that is including the defined designed crew weight)static waterline length could fall into the 12’-6” range (3.65 mtr) would that be enough to satisfy the group that is concerned about it not technically being 12 feet? That is, could they then be comfortable in defending the F12 as being rounded down to the next nearest foot?... which is 12 feet?

What we are really talking about is playing with words…Wouter has made a strong case for increasing the length to 3.90mtr, the numbers don’t lie. This is one of those times were it only costs a dime more to go first class (actually it's free)…why ride in the back of the bus? You can always “dumb the boat down” with a smaller less efficient rig.

By going to more performance oriented hull, the boat will allow a wider spectrum of users as Wouter has been saying from the get go. Simply by changing out the mast and sail…just like we do for windsurfing…each sailor could pick the right size and style sail for their weight, strength, and sailing experience. No one could gripe that they were being treated unfairly because everyone could choose exactly what works best for them.

To recap…a waterline length of 12’-5-19/32” (3.80), an overall length on the bottom of 12’-9-17/32” (3.9 mtr) the difference between the waterline length and over all length would only be 3-15/16” (.1 mtr) Surely a creative designer could tweak this design to get 4 more inches of length below the water line. We could have our cake and eat it too.

Regards,
Bob

Re using waterline length: For powerboats and bigger sailboats, it is an advantage to use the shortest possible length in their boat names, because they pay dockage fees and sometimes ferry fees based upon boat length. (I can picture a great cartoon for this -- like a DoubleX 23 that has a 23-foot waterline but is 50 feet from bow to stern. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Good point. We co-owned a S-21 Sea Ray Sorrento power boat. 21 feet, right? Wrong, 19.5 feet tip to transom but was taxed at 21 feet despite argument with State authorities. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />

I translate this roughly into :

Average singlehanded crew weight Boys and girls 10 - 19 years of age = 50.5 kg's

As it is better to sail underweight then overweight the F12 should be optimised for 55 kg.

My 3.90 mtr design is now down to 65 kg when build light but stirdy (55 kg was/is planned) and has an optimal weight of 53 kg with a competitive range of 38 kg to 62 kg.

Of course it will carry ALOT more weight in a recreational sense.

I think the initial choice to develop a 3.90 parallel to the 3.66 is turning out to be a smart one.

Making the hulls out of unglassed 3 mm ply will make the platform around 58 kg ready to sail and make it have about 70 kg as max crew weight limit.

I seem to remember A-cats used to be made out of 3 mm unglassed ply so a shorter F12 should hold up if they did. Of course these would require more care when handling on the beach and trailer.

Currently I'm also below the laser-1 as cost price (that does include several bought items like rudders, sails, blocks etc).

I'm trying to get close to the optimist cost price. I won't be able to get down to the lowest cost price that is of the Topper dinghy as that is 2000 US$ and that is darn cheap but it is also as slow as a snail. So that is alright.

I've looked at little a rotomoulded materials and found some very interesting info from a knowledgeable source.

If these F12's are ever mass produced then I starting to prefer Twinex and corematt material over rotomolded. Stiffer and is more durable over hard use. With core matt I mean two layers of glass on either side of a layer of sprayed on resin with 50 % microballs. Should be the same weight as ply I think. Please correct me if I'm wrong here anybody !

As the middle layer is resin itself (no foam) the hulls should both be impact resistant and stiff. The latter because of the glass fibre cloth on both sides.

Spraying should really cut down on labour costs.

Wouter

Reading the 58kg is your target weight for prototypes, shall we go ahead and make orders today for 3mm ply?
Allowing a few weeks for delivery? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

I have not been able to figure out what weights of the kids have to do with anything. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />

Well,

I think I've got it all done now. Last items seemed to have come down pretty quickly. Of course building the prototype is alot of work but the basic design is pretty much done. I even got some tricks that could allow making the hulls lighter, just in case. I also was pretty conservative with the weight calcs so you can drop some extra resin here and there.

I even got the costs sorted out to a large extend. If you really want to save cost then you have to build your own sail. Paying a sailmaker to do it for you at 610 Euro's is quite alot when the basic boat without a sail is only 2250 Euro's. And this last quote still includes the dotan rudders a 712 Euro's. If you are going to build this yourself then the ready to sail boat could be as inexpensive as around 1500 Euro's (1950 US$).

When you got more stuff laying around like blocks and shackles the price drop a little further.

I guess that soon the next stage will be to prototype the hull in cardboard at a 1:4 scale, trying to find the right panel layout and then prototype it in real life size.

I think the panels can be twisted quite alot, this should improve hull shape without having to go to compound curves or steaming the ply. It will allow a more pronounced V on the keel at the bow and have it run much flatter near the sterns. But also the sides can twisted a little bit to give hull a raked back bow and a modern wavepiercer bow section. And ofcourse the sterns can be twisted in a little bit as well if that improves looks. The deck is just curved in one plane, should be easier to close the hull off that way.

Yeah I think that with a trick here and there a pretty nice multichine hull can be made. Still I propose a square box shape like the arrows and arrafura's to test the rig and mast setup. These need to be prototyped first to see if the design works as intended. There will be no need to start right away on the more complex (and better looking) hull.

And then spend some time working out the right sail cut.


Wouter

Made a mistake here. The Topper is sold at 3294 USD in the US.

The cheapest dinghy in the US is the optimist from vanguard at 2450 US$

The Byte dinghy is the second cheapest in the USA at 4000 US$

The come the laser dinghies and the more modern boats like the 29-er. I haven't found any US specific quotes on that.

Also, does anybody know what a new Hobie Wave or Hobie 14 costs in the USA ?

Wouter

2006 pricing - Bravo $2,800, Wave $4,400
The 14 went out of production in the US quite some time ago.