F12 design and development

Has anyone mentioned A-class? The boats are extremely equal in performance, but it's a formula class if ever there was one.

Did you get a quote on that ?

But considering that the rudders both act as rudders and centreboards on these F12's an investment if proper gear will be well worth it from a performance point of view.

That is for a class 5 landyacht sail from a very respected sailmaker like R&J sails (supplier of champions in the landyacht business).

You are not paying so much for the materials or even the labour but for this company's expertise and ability to build winning sails.

Building these sails yourself should really be won of the more simple tasks if the panel layout of decent sail would be known.

In the coming weeks I may look very closely to my own R&J class 5 sails and see how it is build up. If it is simple enough then we may be able to adjust it to suit the F12 boat (more draft in sail)

Personally I wouldn't hesitate making my own sail if I knew that I had the panels dimensions of a decent sail. Dacron cloth is not that expensive and the building method is just basic sewing.

Wouter

Currently alot of money is taken out of the design but not using any specilized gear like traveller rails, cleats, blocks, shackles, etc. Surprisingly enough this does safe a bundle.

But in order to make it really cheap you have to accept doing alot of building yourself.

Expecting somebody else to build the stuff at some reasonable quality and then only pay

ice-cream

money is simply unrealistic. The guy doing the labour is doing so to pay the morgage, childrens education fund and his own retirement. Like that it will never be dirt cheap.

I'll show you more of the design shortly

Wouter

I wonder if that is the variance allowance that was put in the original rules when the requirement was that the catamaran for the Olympics would have to be able to be home-built. Obviously, it would be more difficult to build a boat in your garage to the same tolerances as in Marstrom's factory. So maybe they allowed a little slack in the rules for the people who could not get their plywood bent quite to the right shape?

That may be, but part of the reason truly was to allow differences in hull shape. Ie, Yankee Laminates Tornados had a finer bow entry and was pushed to the maximum tolerances at the deck line. This gave the hulls at the bow more volume with the thought being that it would create greater bouyancy. So you basically had four different designs, even though minor between Marstom, Sailcraft of Canada, Reg White and Yankee Laminates. It is too bad that the home built loophole has been closed for the Tornado Association. I think that I built one of the last allowed home-built Tornados.

No. Based on pricing

comments

from a Dotan retrofit post found via google (don't know how old) and roostersailing

OK, I'm trying to help gree identify where this $3K number is coming from.

This setup in indeed the Dotan setup I was looking at.

£236.00 = 350 euro or 457 US$

So 700 Euro c.q. 914 USD for a pair.

That is quite an attractive pricing.

And the rudders will be the most expensive part on the boat after maybe the hulls. For that price I would consider buying these rudders that is if they are up to specs and stiff. As I wrote earlier the rudders will replace the daggerboard to a significant extent so a proper rudder design will go a long way in improving upwind performance.

I've noted this info down in the design paper thanks for looking it up.

Ohh, sorry, but only coined the 3000 USD mark because that is what I'm trying to get to. The onderlaying thought is that Vanguard sells the optimist dinghy for 2500 US$ and I want to stay close to that. Therefor I personally consider anything under 3000 USD a succes for the F12. It is not based on real costs yet. It is just a design goal at this time.

Still it is looking good on this aspect.

Does anybody know what sheets of 4 or 3 mm ply cost in US$ and Euro, highest quality ?

Wouter

Wouter,

If I remember the price correcty the BS1088 was 14 euros / m², so one sheet was ~42 euros. This propably has some sort of Finland tax included, so I assume that it should be lot cheaper in some other country.

--
Valtteri

Two words - Arafura Cadet -!!!
Little brother to the Arrow, home made ply hulls from plans available from the Arrow association, 11' long, (I think from memory 6’ wide), sloop rigged, goes like the clappers, takes an unbelievable hiding and just lasts and last forever, has been a successful class for over 40 years (they have had

national titles

every year in conjunction with the Arrows) and has just recently started to grow in numbers again, is commonly roof racked and stored tied up under the roof of a garage or shed. Seems to me that you are trying to reinvent the wheel? Sailed one up by an adult or by two juniors, and CHEAP.

I googled the Cadet and the first link was to Phill's website. He even talks about building it there.
Cadet

Phill is one of the ones wanting to do this, so I assume he knows why.

The Cadet certainly proves this approach works (at least in AU). The choices of home build boats there is astounding.

What I see in comparison to the Cadet
the F12 has;
no trapeze, no side stays, no fore stay,
no separate downhaul, no mast track and halyard,
no jib and halyard

...a very simple, and short, setup time. Hopefully that is an appealing goal to US homebuilders. A boat that can be on the water in a flash.

I wonder what does the Cadet weigh?

BS1088 4mm x 4' x 8' sheet = $55 USD
BS6566 3mm x 4' x 8' sheet = $45 USD

Oakum ply in stock in New York
will not ship <img src=

alt=

/>

Those Afura hulls look close enough to

good looking

to warrant considering them for the F12.

All the other stuff however will be changed. Reasons :

F12 is still cheaper
F12 is still simpler
F12 is still one or two steps easier to build and rig.

I've got the rig pretty much finished now and it is a really nice concept.

We just need to find easy to build hulls that do look nice at the same time. How easy is it to build the afura cat hulls ? Also 100 hours as the Paper Tigers hulls ?

Currently no shackles have been used in the design, actually one needs to get only the following from the chandlery :

-1- 1 ratchet block (no cleat)
-2- 3 simple 30 mm sheeve blocks
-3- 1 simple 30 mm sheeve blocks with becket
-4- 10 saddles (eyestraps)
-5- about 6 mtr 6 mm or 8 mm sheetline (swiftcord)
-6- about 4 mtr 4 mm racing dyneema
-7- 3 universal joints

All the rest is just lashings and knots.

This my friend equates to CHEAP, cheaper then the afura cat that does have quite a lot of chandlery shop.

Additionally, everything is home made EXCEPT the Dotan rudders and rudder boxed, but the rudder setup could be can be homemade as well.

Wouter

Looking at the Cadet photos on Phil's site made me come to a realization. A kids boat needs to look like a toy in order to be attractive to a kid. An Opti certainly fits the bill as does this Cadet.

Is there a particular stumbling block to building this concept you proposed on the Youth Recreation Trend Page 12 last week?

The F12 simple hull? (I could not transfer the .gif) Now that is definitely a modern look.

Easy to build? In 1979 I built a complete set of hulls over three weekends, and the hardware, mast, sails etc, are also

small

and as cheap as you can get. They cerainly aren't

rocket science

, but a great fun little machine that gives great satisfaction to sail (and race) and they are light enough that one person can

roof rack

them by themselves (without getting a hernia). We bought two of them a few years ago for an association as a

trainer

for members of that associations kids and we picked up both of them for A$500.00 (A$250.00 ea) second hand. Rigging and derigging takes about 15 minutes (if you don't rush it)

Hi All

Firstly, the money that would be spent on the Dotans, would easily bridge the gap when comparing the fittings on the proposed F12 and the Arafura Cadet.

Don't get me wrong but the fittings list posted earlier seems to be pushing the cheap side of the deal, for example, the telescopic battle stick.

I can't find any info on the Impara Cadet anywhere, except for a past yardstick listed with the Victorian Yachting Council, I will try and get to the club and take some photos, it really does look like a 12ft Mosquito, great little boat.

Regards

Hi all,

The Arafura Cadet national championships were sailed here in Adelaide last week & while only 7 boats contested, the quality of boats is high.

The platform only weighs about 36kgs ( class minimum) & is only 11 foot long - so a little short for F12.??

I learnt to sail on one of these fun boats as an 11 year old 25 years ago & they are the only real training boat for young kids in this country.

Darrly is correct that if you drove around the suburbs here you might spot one stung up in the garage unused.

I currently have a set of new hulls, beams & mast in the roof of my shed ready for when my 9 year old is ready to try sailing by himself.

I have a PDF copy of the class rules if any body is interested & i'm pretty sure the class association sells the plans for about $40 au EACH.

Marcus

Sounds like a perfect lake boat. While I'm going to be heavy for it, I'm going to use this opportunity to learn the basics of boat building AND have something that I can just throw on the roof rack and go sailing in less than an hour from garage to launch. Perfect for those late afternoon hookey sessions.

Only thing I'm gonna want to do is throw an MX RAY spinnaker on it <img src=

alt=

/>

Yes, me wanting to allow these hulls to be build under 50 hours of work. This on the advice of phill. If you guys are really building a few of these then you better be able to pop a few out over the winter. Methods like tortured ply take to long.

I think I have a few solutions now. I'm down to only 3

filler and tape joints

. If a series is build then the prototype will be

filler and tape joints

taking a little time to build but after that the original hull can be used to make joints using shaped rods and that should really cut down on building time, allowing a group to pop out hulls rather quickly.

Also I'm now back at normal life responsibilities and so can only work on this design maybe 4 t 5 hours a week instead of 30 to 40 hours a week.

Here a more profiled look at the hulls (called 5 panel chined wave-piercer) that I think we can use.

Wouter

There are two luxuries on the F12 as given now.

A single ratchet block in the mainsheet system to make holding the sheet more comfortable and a telescope battle stick tiller extension. However both can be replaced by respectively a normal block and a plain alu or glass tube covers with some grip material. Afterall this boat has no stays or a trapeze so a one-piece tiller extension won't stick out very far or hang up on the stays/trapeze lines. Like this the cost is maybe only 40 bucks.

I did a quick run of costs and it is way lower then I expected it too be. I need to be a more detailed calculation of cost but currently I'm just below the cost for a new US optimist dinghy by vanguard and that includes the dotan rudders and ratchet block. The rudder setup is now about 35 % of the total cost, with the professionally build R&J sleeved sail at 30 %. Those are the two most expensive items but can both be homebuild significantly cheaper.

Wouter

Wout,

is the hull design finished? If so could you publish your drawings so I can get them to a plotter? <img src=

alt=

/>

Also, would a simple H14 rudder setup work on this?

The F12 looks like fun class, I might be interested in building one if you allow more

Bladish

hull design in the rules. I have built my Blade following the plans and after this experience it should be fun to try on my own design or experiment more on some other design (if wave piercing design is available).

Wife has to agree to take F12 catamaran instead of kayak that I promised to build her next winter though <img src=

alt=

/>

--
Valtteri

Regarding the rudders, I had the same scenario in mind, in the interest of getting on the water quickly. (However, I'm a big advocate of NOT canabilizing old boats, especially an existing H14, even if not in

race

condition, that a kid could enjoy).

I haven't had a chance to compare the dimensions of the Hobie rudder to the Dotan 20. dotan 20
If the area is close to the same, the 11 year old girl, who currently crews with Grandpa in 16A, can probably handle the Hobie system. The other two children (a 6 y.o. girl and 8 y.o. boy) that I'd like to have sail this boat, currently sail Prams and I think they'd struggle with the Hobie rudders.

Phill eluded to a homebuild ply box and rudder here somewhere?

Trey has more rudder systems laying around collecting dust that are orphansed from their boats, and I'm not building this for a 11 year old girl, I'm building it so I can putz around the lake when I'm bored at work and need to get out <img src=

alt=

/>

It is finished in concept. I'm now working out the dimensions of the panels and the curves on the seams. But I must caution everybody that a large extend of hull design is where to place the volume and how to curve the keel-line. Those are things that need to be optimized by prototyping a boat, sail it and then adjusting the hull shape. Probably after the 3rd iteration the hull will be as we want it to be. This will take about 12 to 18 months if we work at it hard.

I don't have the resources to prototype the boat myself at this time so other people will have to do that. Also I think I've done my investment already in working out the design. I'm happy to see someone else do the prototyping and then I can adjust the design based on the feedback.

One alternative would be to buy the arafura cadet catamaran plans and build those hulls. Then you are assured that the hullshape is close to what you want and that the hull construction is dependable.

But if you are a little bit more adventurous then the new 5-chine wave-piercer hull is your candy.

I will be a few more weeks till I have figured out the right keel curve and bulkhead frames. I'm lofting the 5-chine hull in simulation software. But the design is coming, you can be assured of that.

I don't see why not ?

If the rudderboard area is large enough then by all means use any catmaran rudder system that is available to you.

The only other requirement of the rudders is that you should be able to balance them, afterall we are using the rudders as daggerbaord replacements and so unbalanced rudders will have very heavy weather helm feel.

Wouter

Certainly in the initial phase I shall not limit any hullshapes. Lets see what we all together come up with over the timespan of the next 2 years. After that we may settle on a signle hullshape if that is required.

I'm convinced wave-piercer shapes are possible.

Wouter

Trey,

What is your body weight and length.

I'm not garanteeing anything bit maybe I can just design your hulls to carry a little more weight.

Wouter

I'll do it, as I'm more interested in the building process than the actual performance.

Sounds good. I'll shutup until then.

EXCELLENT !

That is just what we need for the prototype.

Till then.

Wouter

If anyone's interested, I've worked Wouter's idea into this:

(Image deleted. See attachment.)