Mark I'm hoping that as long as the hulls look modern and can handle the unstayed rig, it wont be too hard to reinforce sidestay and forestay positions if neaded during the building process, to upgrade the rig anytime. Then I would have cats suitable from 7 up to learner adults. I have the tools, workshop and have committed myself to building at least one cat with traps next winter and would like to setup a production line for the club if possible. I already have Chris's option and would love to see RG's so go for it guys lets see your plans <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
regards

The tubular frame is also a good place to rig a spray and wind deflector if desired, at the cost of some aerodynamic drag.

Is there a way to make the frame somehow more atractive? Given enough time, the best engineering solution will become the standard of beauty, but in the short term style is a key marketing issue.

OK, here is my design, a bit modern for sure, but 11 kids have seen it now and all with no exceptions wanted one yesterday. Whether the rest of the planet is of the same mind, only time will tell.
I designed this so it will have 2 hull options, most of the pic's that follow are of the hard chined version because that is what I believed would spark the initial interest, the round bilge version (similar profile) is based around my new F16 design with the appropriate changes and is more geared to older kids, a conventional rig and traps, perhaps even a kite. I'll finish this version as time or interest permits.
To get the round bilge one out of the way, its the first pic, all the rest are of the hard chined version.
I should also note that everything is within Wouters posted guidelines except for the luff length which is just a bit longer.

Cheers
RG

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The luff length as given by my was determined by the stiffness of the mast and what I know will work from my class 5 landyacht sails. It is not a hard boundery. I'm already thinking to stiffen up the mast to have it bend less and allow the battens to pop more easily in light winds. This desire coincides with the desire to use the same section for the beams and the bottom part of the mast.

How much is your luff longer ?

Wouter

Thanks for sharing RG. What's your target crew weight? Also curious about the narrow transoms. What's the thinking behind that? I know your A cat hulls are also narrow at the stern, but also through the whole length I think, so this seems like an interesting departure.

Mark,
65 kg would be the max if you raced it but I put enough in it so its comfortable at 120 kg (kid & adult) also. Best range would be 40-50 kg.
Hull transoms and/or narrow hulls have nothing to do with narrow, its all about slightly lower drag and minimizing the pitching. The 2 hulls show are actually quite different but both do the same thing more or less. The round bilge hull has more than 8% less WSA, is more than 6% fatter and almost 10% more WPA and a fatter transom than the hard chined version, yet the pitch rates are almost identical (within 1%) so just looking at physical sizes has very little to do with the dynamics. The thing you might have missed is that the chine goes downwards for a long ways aft before it rises again, is quite good for keeping the transom out without having a big fat shape at the back that just drags water. The other thing to remember is that if you can keep the pitching under control, you don't need a lot of reserve buoyancy at the back to counter stuff thats not happening.
Wouter,
197mm longer
RG

I would have thought that the narrow transoms would help sit the back down when your aft in a blow and make keeping the bows out easier, no ?
Aerynt

That's really great! I want one too! There are hundreds of positive things I could say, but they wouldn't help as much as some constructive observations:

1) That gooseneck looks like it would "bite" the fingers. Would it make sense to use the Laser standard system - and perhaps the same boom as well? Maybe another boat's standard system that fits?

2) Each mast support tube is curved near the extremity to enter the deck perpendicularly, when a straight tube cut in the right angle would be easier and cheaper to manufacture. Is this for aesthetic reasons, to provide a better holding point when hiking/trapezing, or for yet another reason?

3) Why the rudders seem to have no Ackerman compensation? It would probably facilitate manouvers.

4) I'd like to know if what Wouter wrote about daggerboards stands true with this design. How much would be lost if one daggerboard was eliminated? And without daggerboards? Would it still beat a Laser? In my opinion, the boat just has to outsail the Laser. Faster than that might be too much.

5) Is there anything else that could be done to simplify or improve its maintenance, use and safety?
Built in beach wheels that double as fenders/bumpers when raised? Hard tramp? A **** for safety? Back rests? Single rudder? More grab points for beaching? Butterfly nuts in the bolts that attach beams to hulls for easy assembly? Standard righting pole? Reefing system? A shark's mouth painted in one bow and a big smile in the other? (just brainstorming).

Great job!

Very interesting...great start.

Comments and Questions:

1) Any reason for not putting more volume lower in the hull?

2) The profile looks hot but the head on view makes the hull cross section look quite dated… As if you have a very up to date profile, but a 20 + year old hull cross section.
Is picture # 123637 depicting the same hull as shown in picture # 123641? It may just be an optical illusion… but the picture shown with the rig on it looks like a “stretched out version of the non rigged hull. The picture of the hull ( #123637) looks stubby in comparison to the hull in picture (# 123641)

3) If you are going to have dagger boards why would you want such a deep V hull section? Small mono hulls are fun because they tack “on a dime” Would not a flatter bottom shape make the small cat tack much easier?

Best Regards,
Bob

Luiz,
yup, the gooseneck is a mess but the piece it's mounted on is tricky, first the tube there is a clamp (2 half shells that open so you can rotate the mast into place, this just leaves the aft half to attach the braces to and you can't rivet anything to it, so whatever is there will have to be welded, next the right angle at the outboard end of the braces goes into a molded recess so the whole brace just drops in vertically, this gives us more bearing area and holds the brace in position while you rotate the rig up to the clamp, seemed like a better way than trying to juggle to pieces that can move at the same time.
As for the rudder compensation, I just hadn't got around to doing it yet, rudders came off the F16 design which has canted hulls and so its not necessary.
As for boards, a quick look showed that the leeway angle was excessive without them, so they got put in.

Bob,
Lower volume is no problem, just use the round bilge version of the hulls, I had thought that the reason to do hard chine hulls was so that it would be easy to make these from playwood and keep it all cheap? The hulls are all the same in the pic's, its just the perspective. As for the deep V, due to entry limitations that are inherent in what you can twist play into, the waterline sections in a hardchine boat are quite draggy, you can offset that a bit by keeping it narrower but that gets you a deeper hull. I don't think there is a perfect answer to this one, it really just gets down to your choices and what you want.
Cheers
RG

RG those hulls are fantastic what sail area are you considering to be maximum and minimum
regards