Kids F12

Like ncik, I too was worried about the loss of section moment in the main beam if you put the mast through it, plus 4 attachments for the x-brace makes for a hassle if you ever have to tear the boat apart. Also, means 4 more attachment reinforcements to the hull.....just seems like a lot of fiddly stuff.

Personally, I'm not leaning in any direction, just find it fun trying to deliver something everyone wants, quite a nice brain teaser if there ever was one.

Did the 75kg crew hull, gunwhale is the same, profile the same, just changed the chine, was a nice surprise that the drag coefficient for the hull went down, but not as much as the wetted area went up, so nett gain is to drag (0.7%) but it does produce more lift (sideways) and the overall hull L/D is up by 1.3%, so point will be higher as will VMG

Jeff, my wife is 61, so its a safe bet she'll go for whatever is easiest....more amazed that after all this time she actually wants something I designed <img src=

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Pics of 2 hull comparison attached

Cheers
RG

2 hull comparison #2

2 hull comparison #3

Gero,
That is the system I'm using. It was one of the key points of my design back in 2003.
Since then I realised you don't need to make a hole in the main beam.

I have also considered non essential stays that could be used only when required to stabilise the mast for heavier crews.

I always intended a modern cat version of the Laser.
In more ways than you mentioned.

BTW:-
We have one of those cats with the struts above the deck at a local sailing club when I was there a few months back.
It was offered to me for $350, not that I was asking.
So anyone not wanting to build a boat and happy with the struts I know where there may still be able to get a boat.

Regards,
Phill

Good

(using that term loosely) thing about a laser is that you don't need to lift the rig too high to get it in. Bad thing about lifting the rig is that it is pretty heavy.

How about a system like the existing cats where you lock the mast step into position and walk it up, but instead of having stays, have a gate at chest level that you can lock around the mast? It would be extremely easy to rig with very little chance of dropping it.

Might have to put my designing cap on for a couple of nights next week. Getting a bit bored of work related engineering.

I have an easy system to stand the rig which also doubles as means of helping the crew get back on the boat.

Currently the limits for the F12 are as I defined them a while ago. I had my reasons to settle on these specs but I'm not sure that this means that they are fixed and agreed upon.

I decided on the following specs.

Overall length 3.750 mtr
Overall width 2.000 mtr
Max mast length 6.000 mtr.
Max luff length 5.300 mtr
Max sail area 7.000 sq. mtr.
Min weight 60 kg

Optimal crew weight range 40-65 kg

For long while now I was steering toward an OD class setup much like the Tornado is now. Where the hulls are narrowly defined to a single shape. The same for some important elements like forcing the unstayed rig and the collapsable mast. Other things like sail design, rudders, stocks, trampoline design and the way the unstayed rig is supported were intended to be left open.

This is the only way I can see this design remaining easy to build and inexpensive to build while allowing enough freedom of design. I strongly believe that when the hulls are allowed to differ, as well as items like the mast, that then the class will only need a very short time to become prohibitively expensive. Or scare away the parents as they will believe, not without reason, that a rounded keel hull with daggerboards is more competitive then a hardchined boardless design.

Of course the more important design goals explicitely advice against such a situation :

-1- (home) buildable for 3000 Euro or less
-2- (home) buildable for 100 hours or less
-3- (de)riggable in 5 min or less
-4- fully (diss)assemable in 10 min or less

These design goals may appear arbitrary, but they were derived from the wish list as provided by the interested parties and the start-up planning for the F12 class.

I haven't seen any convincing arguments yet to let go of these limits/design goals. The argument giving mostly is increased performance or that an adult wants to sail/race this boat. I feel that other designs like the Hobie 16, F16, F18, A-cat and Tornado are the right classes for sailors with such considerations, not the F12 for youths and as a simple recreational craft for light adults. Otherwise the F14 sounds a lot more promising for these guys.

Wouter

I know everybody thinks I'm the reincarnations of the Devil, but I really don't care whether some person widens his F12 for himself. I actually adviced John (flatlander) to do the same last Januari.

It is just that I do believe that the F12 is for kids, it is an entry level cat, and I don't see how you can make it work equally well for 40-65 kg youths and 70-80 kg adults. It will be mediocre in both aspects or very poor in one of these roles. I personally choose to stick to the orginal F12 idea and go for a craft that is well suited to the 40-65 kg target group and refer the 70-80 kg sailors to the Hobie 16's, F14 or F16's.

For some reason people believe this conviction is some irrational opinion on my part. Weird. And then when I turn around there is another guy accusing me of wanting to make an F12 for myself and my own weight (90 kg). How can I be blamed of both at the same time ?!

It is an absurd experience.

Apparently it doesn't really matter what is said as long as everybody can blame dear old Wouter of something. Then everything is alright.

This basically means that you are splitting of the main F12 project here. Which is something you can do but would you mind changing the name of your design at the same time. I think the F12 project has to run on this forum a little longer before we have a concensus we can act upon. As this project predates your involvement, it is only fair to reserve the F12 name for this project only.

Wouter

Yes, Phills design is far more along those lines. I think he is also used in pod in which you can just drop the mast.

I eventually decided against this as the unstayed rig will need to be supported both along the centreline and perpendicular to the centreline. In effect you'll need to dolphin strikers then with one running along the centreline to the rear beam or something. I my opinion this comes close to have the famous kneeknocker bar of the old Nacra 5.2's. Also I feel this contruction is both more complex and more expensive then the push rod setup.

The push rod setup have other advantages as like much lover stresses in the involved components. But I won't go into detail here. The pushrod setup is also simpler and quicker to homebuild as it can be made up of plain parts like round alu tubing and standard marine hardware like eyebolts, threaded forks, plain bolts and clevis pins. There is no bending of straps or tubes involved.

Two added advantages of the push rods that I was after are the ease of sliding the F12 on its beams on the supports (plain plancks or beams) of a trailer or roof rack and the ability to grap this structure by the sailor when getting back on board or handling the craft.

Wouter

Yes, that is a possibility. In my opinion something like 3 mm dyneema line will be up to the job. The attachment points of the push rods to the hulls will provide a strong enough point to take these.

Limiting the sideways bend of the mast is one of the more promising performance enhancers.

The stay going to the front is a different matter but just as we do with spinnaker pole support wires we can easily drill small holes in the very tips of the bow and secure a twin forestay to those.

The more difficult item to solve is how to do the hound fitting on the mast with a sleeved mainsail on it.

In my opinion it is yet again one more thing. It is very easy to add parts to a design, but I'm not sure that is the best way to satisfy the stated design goals. I think that I strongly feel that the F12 is a

less is more

kind of concept.

Everything that is not stricktly necessary is better left out. This is one reason why I'm trying to get rid of the camber inducers as well. Afterall, each items adds both cost, building time and rigging time. These things do add up.

Wouter

This may be a good moment to familiarize yourself with the F12 design as it stands now.

With the pushrods, you secure the bottom of the mast to the mainbeam by sliding a bolt through the mast section and two eyebolts that are secured to the mainbeam. The mast is laying horizontal and parrallel to the hulls. The other mast sections are now inserted and possible the sleeved sail is slid over the mast. The whole rig can now be walked up and it will fall into the brace that the two pushrod together form. Slide another bolt throught the mast and the eyes and your are done. An alternative here could be a brace that rotates in front of the mast to lock it. I haven't decided here yet.

An alternative way of rigging would be to fit the mast and walk it up without the sail slid on it. Then the boat can be layed on its side and the sail can be slid over the mast that way after which the boat is righted again.

I have to move the rig into the pods on my landyachts and yes it can be done but I found that at my posture of 6 foot 2 and 90 kg that it can still be a muscle job. That is why I spend time on working out the above setup.

Wouter

That is it for me today, I'm off to work.

Wouter

Naughty, naughty Wouter, you changed the specs and didn't consult anyone that I'm aware of....you little Hitler

decided you need to consult people, but thats a tad hard to enforce, so I did something practical.

The following is free to anyone who wants to take it on with the sole exception of Wouter....Rick and Mary come to mind if they can stand the aggrevation as they appear to be the ones to started the forum to get this going.

Tonight I got the international trademarks, copyrights and web domains for the following:
Formula12 .net .org .us. .us.com .eu .eu.com
F12 .us.com .eu.com
F12cats .com .net .org .us .us.com .eu .eu.com

and further I have bids in and will probably have by tomorrow
F12 .net .org

Wouter....time to play nice nice and listen to those folks here and not tell them what to think

Everyone else....its party time, now lets do something useful with F12 that benefits the kids and the sport in general.

Suggestions for people to oversee this/run this are welcome cause I don't need another career.

Cheers
RG

Again with due respect, have you read all the previous links? I for one see nothing new in the information regurgitated by Wouter to you here, it is all previously documented.

Yes MAJOR thanks to Rick and Mary for starting this forum...as a direct result of the Youth Recreation Trend thread.

Maybe consider another thread

Alternate F12 design Mk II

? Woah, I've become a Wouter apologist <img src=

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Thanks RG for doing the comparison of the Original to the 75kg hull design…from what I can tell from the renderings it has confirmed my assumption…

The depth of the hull, width on deck and general design shape appear to be very near the same (at least at the cross section you provide) with just the width of the hull at the water line increased by about 1”…if this is the case, it is very hard to argue that increasing the F-12 design parameters to a crew weight of 75 kg would spoil anything in the way of safety, ease of use (weight), handling or performance for a younger child. It appears as if there is a mind set that sees all these little optimist sized cats flooding the sailing scene when in fact a boat capable of handling a greater crew weight would serve a greater variety of size kids, have a wider appeal to parents as their child will not “outgrow” the boat so quickly and as such, be more economical to own.

regards,
Bob

Bob,

Pretty much all F12 designs presented so far could carry more weight, but that doesn't mean that the competitive weight range is expanded to 75 kg.

Compare it to a F18 carrying over 200 kg (over 420 lbs). It can do it without any problems but you still won't be competitive with crews weight 145-155kg.

It is the same with the F12. The design was always intended to be able to carry more weight recreationally as it was agreed upon early on in the project that a parent with kid should be able to sail it (when the child first learns to sail it).

When we talk about a (competitive) weight range running from 40-65 kg than we are refering to youth RACING and not recreational sailing. Of course, adult can race this F12 as well but then to make things fair we need a minimum crew weight rules and split the racing in to groups.

the youths : 40-65 kg
the adults : over 65 kg

The adult will go around the course slower then the youth but as all adults will go slower by equal amounts the racing inside a group will be fair again.

And that is the end of my coffee break.

Wouter

Hey RG, I really like what you are doing with the F12 design. Many thanks for participating...<img src=

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Here is a video of the Open Bic that is being promoted by West Marine...They have totally beat the catamaran world to the punch with this concept and presentation. Set up in two minutes, easy to rig sleeve sail with freestanding rig, under 100lbs, near indestructible roto-molded, $2,700. US I know this boat has been talked about before on this forum, but I thought that a look at how they are marketing it would be of great value.

http://images.westmarine.com/video/OpenBicVideo1.html

Regards,
Bob

After watching that movie, I think I want to have kids so they can sail one of those!

Okay, so maybe not that much, but still it seems to be well marketed and alot cooler than the optimist, so now our cat has to beat that thing around the course.

gree2056... not only does it meet just about every criteria that has been set for the F12, other than being a catamaran...it is being manufactured and MARKETED by an established name in water sports with a huge world wide dealer network already supplying kayaks, surf boards, Sailboards, and now sailboats. This will definitely dilute the market share for the F12 catamaran. Those seeking a small high performance boat for their children now have a viable option to the Optimist.The F12 will have to take it up a notch in performance to stay ahead of the curve.

While watching the video it is apparent that they know how to market their product. The optimist was an easy target to shoot down... this Open Bic is going to be a lot stiffer competition.

Picture this, you take your 12 year old down to the sailing site...there is a home made, flat paneled, boxy looking F12 made of plywood...it has a

brushed on

paint job... with a rig that resembles some of the land sailor rigs posted...beside it is one of these sharp looking Open Bic's...He is a kid with no bias for or against catamarans, if you tell me he would not choose to sail the Bic over such an F12 you are lying to yourself.

The F12 better bring it's A-game, it will need to totally dominate on the water in order to overcome the media budget and maufacturing effeciency of scale that Bic has in play, in addition to overcoming the long established history of the Optimist..

Regards,
Bob

JeffS and his kids all took a spin on the Open last March. I've had my neighbors say they'd like to have one to, as advertised, be the next step past the Opti. Tough to justify the $1,300 hull only price when you think

how long will this 8 footer keep Johnny happy?

When will he be wanting for a Laser? Tough for just one of the bunch to justify buying Open hull only if the others don't make the move as well. They've got solid opti (OD) sailing and numbers, so why upset the apple cart? This is where the F12 will shine, I think it will satisfy a broader age span.

Agreed the Open looks sharp, some of these F12 designs look good too. <img src=

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/> The F12 must look fast to survive.

Mark II CTMD F12, sorry I'm not as good on rhino as RG. Jeff, yes you could use rotating centre boards, however I will show daggers as standard.

Chris, since you've stuck with a stayed mast and dolphin striker, are you considering the possibility of a trapeze?

And target crew weight is still 45-50kg, yes?

Mark,

target crew weight is still 45-50kg (I've left some extra freeboard in to cater for heavier crews or two people).

The concern with trapping is the extra compression load applied to the rig. The rig I'm looking at is designed for a two person, one on trap dinghy (MG14). With a 60kg person hiking on the cat the mast will experiance similar loads to what it would see with one person trapping on the less stable mono. I've gone with this mast at this stage because its similar in shape to most modern cat wing masts and because fully rigged it will be less than 6kg (a weight that will enable kids to rig their own boats). If you wanted to be able to trapeze its only a matter of talking to whoever you buy the extrusion off and discussing what section they would recommend (you'll propably end up a couple of kgs (4lbs) heavier at the most). The beams and dolphin striker as specified would be fine.

Ok thanks Chris. Presumably no expectation that trapezing is required from a righting moment point of view.

BTW, a question that I also asked of Phill a while back - what do you see as the next step for kids moving out of your F12, either in terms of existing boats or design parameters for a new boat?

Mark,

a 45kg kid sailing this boat would be approximately equivalent to a 70kg Paper Tiger sailor in terms of the ratio of righting moment to heeling moment. While obviously not required I'd also encourage people to build a reef into the main sail so that the boat could be calmed down when required.

Where to next is a difficult question. I competed in my first adult Hobie nationals as a 45kg crew at 12 years of age on a Hobie 18. The obvious answer is a 14' boot (F14) but for most of these you'd want be at least 65kg so depending on the kid and the location you would either keep them on the 12 until they become big enough for the 14 or put them on a 14 and be willing to lock them in the car on windy days.

In the southern states of Australia I can see a very beneficial development being...

F12 --> Paper Tiger --> Mossie --> A cat/ F16

Thanks Scarecrow great looking boat, I was really for traps as you know. We had a light day a couple of weeks ago and I let the kids captain the A, with me not recommending anything just sitting and getting them on & off the beach. They didn't want harnesses or to hike out they were happy with the speed sitting in. They wanted lots of turns, capsises and fun which they had, regarding the dagger boards that I was concerned about, they stopped the boat well of the beach to pull them and release the rudders, my plan is to have a few different length sets of daggerboards to suit experience and kick up rudders. Just from observation I think it was me that wanted them on traps <img src=

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/>. The kids would happily sail your boat. As for me the Olypics decision has brought me forward and am currently getting quotes on bulk gear for a build starting early in the new year
regards

Just a stupid question. There is a lot of talk about crew weight, rightning moment and so on. Are you basing these on solid hydrostatic calculations or are you just preforming advanced guesswork?

Good question Gato <img src=

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a composite set of hydrostatics for a couple of winning Uni-Rig boats would look something like this:

LCB 46.7% (fwd of transom)
LCF 45.5% (fwd of transom)
Cb 0.511
Cm 0.809
Cv 0.946
Cp 0.632
Cwp 0.754

My design which is geared more towards the heavier weights performance wise (to keep the heavier (50 kg+) kids from getting bored) looks like this right now:

LCB 47.3% (fwd of transom)
LCF 45.3% (fwd of transom)
Cb 0.393
Cm 0.619
Cv 1.432
Cp 0.635
Cwp 0.797

Would be interesting to see Grob's, Scarecrow's and Phill's numbers also if they have them. I don't think we need to hide these parameters as everyone will eventually see them anyways when we publish the plans and anyone can back calculate them. I would have included something similar to my design, but I don't have any lines handy from which to build a model to compare with, if anyone has a CAD model of something even close, please post it it and I'll throw a hydro's model together for everyone to look at.

Cheers
RG