round bilge #2

round bilge #3

round bilge #4

the last one
round bilge #5

Flatlander,
Sorry, haven't seen the "Youth Recreation Trend" thread, but I'll go look at it now.
I'm sure that boards are a pain as far as maintenance goes but you can engineer in some healthy safety margins also. If thats not acceptable I have done a couple of skegged boats in the past that had sort of adequate performance.
As for group building....thats great, but I still doubt you'll do one in a weekend....cuts into the beer drinking too much <grin>
Cheers
RG

I can't say that I understand the underlying logic here. I do know however that there isn't a single weld in my design. Also several fittings have been further simplified from the ones given in Gareths CAD drawing. As such I don't really understand why you feel that one "has to welding something".

No disrespect intended.

Wouter

Wouter,
send me a drawing so I can see what your talking about... just can't see how you can have a rivet bubble end inside a tube that needs something to slip into it, be it the mast/mast step tube, or the brace clamp.
RG

The main point I made was about the flexing of the mast that is the result of it being unstayed. That point still stands and it is hardly irrelevant. You loose sail area that way and alot of people were inmediately turned off by the bend mast in my (Gareth) CAD drawing. But at least that one was realistic if not conservative be showing the maximum mast bending.





Well I'm not getting into a pissing match with you here. Let me suffice by asking all the readers here about who will be seriously thinking about homebuilding this boat if it takes 500 hours or even more ?

Without homebuilding, how do we kick-start the class ?





You seem intent on misunderstanding my comments.

Let me suffice in saying here that there are many boardless catamaran designs out there that don't perform badly at all. As a matter of fact, the much heralded 49-er high performance skiff (with a large daggerboard) is rated the same around a race course as that boardless Hobie 16 or Prindle 16, both of which have less upwind sailarea then the 49-er and don't even have a spinnaker.

Now you may explain to all of us here what causes this remarkable result !

I'll give everybody a hint, it isn't the result of well rounded keel lines.

Additionally, if the idea is to outperform the laser dinghy and other dinghies, who are all much more narrow and also WAAAAAY slower then 49-er, then the Hobie 16 and Prindle 16 daggerboardless character may well hint that the F12 may do very well in comparison without a daggerboard as well.

Wouter

If I understand your reasoning right then your "plugs" are intended to be slid in and out when rigging or derigging the part/boat. First of all, this assumes that the connections can only had when such a fitting it used, this is not the case. There are non-plug-sliding alternatives. I'm using one of those. My setup uses at this time only eye/bolt and eye-bolt/fork connections. The latter being rigged/derigged by clevis pins.

But to answer your question directly. Bajonet fittings come very close to what you are describing. You can always route a groove in the plug with a straight angle in it. The bulb of the rivet then runs through this track and by rotating the plug you secure it axially. Securing the rotation of the plug is not needed in all instances but when it is then there are quite a few alternatives as well.

I'm still waiting for the Hawaian clamp description. But it it is what I think it is then that is also a way to secure the brace to the mast, this time without any clevis pins or bolts what so ever.

Of course one can always use clevis pins to secure part that slid into a tube and need to be taken out often. As the rods in the F12 design are most heavily loaded by compression the clevis pins don't have to take the real loadings as a simple rim on the end of the plugs resting on the tube endings will take care of that. Again, that is what my design is now using. That is another reason why the push rod setup is advantagious. Basically the way things are now the plug is most pushed deeper into the rod. Securing this has endless alternative. An additional brace running from the sides of the push rods and around the front of the mast will then be there to prevent the mast from being pushed out to the front on downwind legs. This brace can even be a simple lashing. I say "can" here as I personally prefer a stiffer method of fixation, but the point made is simple enough. You can actually use rimmed plugs that just slide into the push rods and have a single brace (=lashing) fixate the whole setup in one go. Easy, quick and inexpensive to make if we repeat setups like this often enough then we may well get very close to the stated design goals, the 100 hour building setup included.

I'm sorry I can't provide you with drawings of these setups as that will take to much of the spare time I can spend on the F12 project. However, I think these verbal describtions will suffice.

Wouter

Here are a couple of observations.

1) Too much emphases is being put on “home building”.
It has become the major force driving the design
Is the main purpose to get kids out on the water? Or is it to turn dad/mom into a boat builder? There is a difference between having the “option” to home build (a good thing) and having the whole class concept pivoting around every design being home build able in plywood ( a bad thing). If one takes off the “plywood glasses” the design options open up considerably.

Out of the thousands of Cat sailor forum users how many have actually built a boat from scratch? You can probably count them all on two hands. Realistically very few people have the expertise, time, tools, and work space (it takes all these things) to build even a simple F-12. How many of these “clubs’ exist that are going to crank out an assembly line of F-12’s?
What Club is going to want to take on the liability of inexperienced Kids and/or their Parents being injured with power tools at a Club sponsored build?


2) It is called an F-12…if it really is, than their will be multiple designs to choose from, even ones designed by the parent or child themselves, yet there is already questions being raised about a rounded bilge design making the hard chinned design outdated. If this is truly going to be a Formula class (which is one of the positive features of the proposed class) then this has to be accepted as the nature of the beast. Just as there are Blades, Tiapans, Vipers, Stealths etc in the F-16 class, their will be multiple designs for the F-12 as well…why is that a problem? I find it encouraging that at least three individuals are working on independent F-12 designs.

Best Regards,
Bob

Well said Bob, RG seems to be working on a boat that may lure kids to cats, Wouter and Chris seems to be working on a cheaper boat to lure kids to cats theres plenty of room for both. Keep posting your ideas guys whats wrong with building quick boats for the club and lovingly building a boat for 500hrs with your kid if your that way inclined.
regards

Plans are not started yet as I'm not sure if I have yet delivered what works for most people?
At the point we get to that place it should take about a week to knock out a set of detailed CAD building plans.
RG

RG, For your boat to work for me, optimize it for a 75kg crew! <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> I want one to sail myself! Oops, this is the Kid's F12 thread.

The field is narrowed to a few committed to build. Like you and Bob and Jeff have stated, why worry now? If Jeff's and his boy's are happy they can start building.

I propose the question may be not does this work for most people, but is it within the parameters of the Formula 12 and are those parameters fully defined or agreed upon? If not, this design may end up a one design. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />

Don't need to rush the plans for me our sailing season is only 4 weeks in so I can't build for 6 mths. If the F12 parameters don't encompass every type of 12 ft cat currently sailing its surely doomed because the ones out there are doing it already. As I am running our junior sailing my yardstick plans are a simple weight of crew and sail area.
regards

except for the luff length its within whats listed here as the parameters. To push the hulls out to 75kg is no big deal, but it won't fit the majority of the kids then, if you want a larger displacement version, I'll just customize it for you but it probably won't make Wouter happy <grin>.

As far as I'm concerned its already a success because my wife who is "NOT" a sailor wants one <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> see attached pics, she's already picked the colors to paint it <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />....not my choice but hell, its her boat. I'm sure Aerynt and his boys will build 2 starting in the next few weeks and a couple of local clubs just approached me about a joint build of 16-18 of them.

So long as the rules don't get changed I don't see much to stop anyone starting.

RG

Another of her paint job

Why is having a hull design that would be competitive with up to 75 Kg a problem?
The class would have a much larger appeal. Instead of dumbing down the platform, why not make the hull design with as high a performance level as possible. Reduce the size and simplify the rig for those with small children or those desiring lower performance. There could be as many as three different size rigs…one small simple rig for the 7-10year old children, a slightly more sophisticated mid size rig for larger children of 11-14 years of age, and a fully optimized rig for older teens and adults. I think parents would be more inclined to buy into a class that their son or daughter could make use of from grade school to high school and beyond with just a rig upgrade.

What novice sailor could not use the extra stability a slightly larger volume hull could offer? After all it is only twelve feet long regardless, and the weight penalty would be negligible. RG if you have the time it would be very enlightening if you could do a rendering of your current F-12 design side by side with your interpretation of an F-12 expanded to carry a crew weight of 75KG. With a visual of how small the difference would be maybe there would be less resistance to a 75Kg crew weight target.

Best Regards,
Bob

A thought came to mind while looking at RG's renderings. Have any of the people considering free standing rigs considered the option of using the dolphin as a socket. ie use an oversize striker tube and then run a X pattern of straps rather than the traditional St. Steel strip. It would then allow you to get rid of the struts.

I've also considered this, but instead of an X frame, a dolphin striker strap plus a strut running aft to the rear beam or a mid-tramp beam. Simpler because there are easier landings than for an X frame. One problem (sorry, "opportunity") is that you will require a main beam wide enough to take a hole for a mast to go through.

The only reason I can see for a stayless rig is for easy rigging. How about a compromise, lower struts for standing the rig, then stays for stiffening up the top of the mast...like a 420 with its mast gate. Very easy to rig.

Dare I say the talk here is tending towards a cat version of a laser...three freestanding rigs for a single platform...I like the concept.

btw, those moth photos are not of Rohan or his boat. It is a UK developed moth, home built actually! I think by one of the top UK moth sailors, he may've won the previous world championships between Rohan's wins.

I thought we had already seen the picture of your wife and was worried about opening that attatchment <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />. I noticed she doesn't want sidestays.
regards