I think Gato is on to something here :

http://www.gust.ax/gallery/f12/2/

See the galleries of

- A new cat
- The start of a new cat
- The beam landing
- Cats everywhere
- I'm sailing
- Sailing faster

The simple foam strip construction he uses appears viable for nice compounded curved hull shapes and seems reasonably simple to contruct by amateurs.

Have you measured the weight of the completed hulls Gato ? And how much is each ?

How many hours were involved in making up a single hull excluding building the jib ?

Wouter

It is definitely a good method to be used by armature home builders. Don’t know if you have been checking the sshhh thread there is a little bit more on the building there.
My hulls are a little overweight as I used a heavier cloth than needed, because I had it laying around in my workshop. If I remember right I ended up at something between 13-13,5 kg, it should be possible to make them around 12 kg.
When the jig is setup you can rip the strips, lay them, glass the inside, install transom and frames make the beambox and the fittings for forestay and shrouds in one day about 6-8 hours for one hull half.
The two halves made its not a big deal to join them and glass. In total I made Had the Tabby on the water in five weekends guess 50 hours (not painted).

Thanks for the quick reply Gato.

I appreciate that.

I have read up on the sshhh thread and have gotten some more info I was interested in. Part of it I has already guessed from the pics in your galleries.

A note. In the F16 class they use seperate decks that are glued on later to properly tape in the keel line from the inside. Some are quite adament that this is needed when the craft sees hard use. Tp prevent the hull from splitting open. Apparently only taping from the outside is not enough in the long run. Just something I wanted you to know.

I'm very interested in your Tabby cat and how its construction holds up. Mostly because I personally have a double edged problem. I don't have access to a dedicated workshop and typically I do all the boat and landyacht building out in the carpark in front of the flat I live in. Individual stages must be finishable in a single day. Additionally, I can't occupied the space for more then a week or so before I get complaints. The second problem is the area I sail. I have strong doubts about the freeboard on some of the F12 designs so far. The north sea is one of the reasons why all the F18 designs have increased freeboard significantly over the last years. It is also what makes the AHPC Viper F16 such a good boat. Greg Goodall of AHPC specifically commented that they learned over time that freeboard is more important in dive resistance and recovery then bow volume. The Aussie Blade F16 is following this trent together with the Viper F16 and the new F18 designs.

I feel that the foam stip plank method you tried is viable for me personally and allows me to get a platform more suitable to true beach cat sailing where there is a surf to traverse.

And you are an inspiration to us all Gato, I'm certainly no exception to that rule.

many thanks and I'll be keeping an eye on your blog page

Wouter

Thanks for the kind words. As for the joining of the two hull halves ncik has a good flanged setup in his drawings. As my intention was to build fast I made some compromises.
For the freeboard I understand your concern, but this is a cat for kids and with the quite choppy sea condition we have here there is no real problem in the conditions you send out your kids on the water.
As for adult sailing for fun I think a 14 feet version with a moderate sailarea and a spar not exuding what you can cartop would be the solution, and there I think that such a cat would benefit from a higher freeboard.
I’m thinking of building one for myself, it would perfectly meet up to my needs.

Gato,

As far as I'm concerned you deserve every praise that is coming to you. A great deal of designing is just giving something a try and see how it comes out. You are almost singlehandedly doing that portion for the F12 class.

Ohh, I forget to ask last time. What is your body mass and length.

I ask as it appears the Tabby lifts just fine with you on board. Now I don't expect you to be of my stature but nevertheless ...





Now, what I'm personally lacking in the "just build it and see" department I make up for in analysis. That is what I did in the F16 class and what I also did in the F12 class.

I actually believe that the F12 can work well for adults. Meaning 85% of the adult women and about 50% of adult males (when keeping the 2.00 mtr width). You may well fall in the last category.

The 7.00 sq. mtr sail area on a 6.00 mtr stick is not really limited to youths. Afterall the laser dinghy has the same size rig with a very oudated sail design and is only 60% slower then a fully charged F18 racing catamaran. This Laser dinghy is actually sailed best by a 80 kg skipper and can be very fast downwind (where it is much less limited by righting moment of the crew).

Additionally, the loading of the F12 hulls and rig is on a par with a 135 kg crew on a F16 when you are around 60 kg - 75 kg. They specificantion that may need to be adjusted is the overall width of the F12. For skippers over 70 kg it is best to make the craft only 1.80 or 1.75 mtr wide instead of 2.00 mtr (and just keep the same rig).

The following combo's of boat weight x mast height x sail area x crew weight x width are very entlightening :

The named ratio is the righting moment of the crew on the luff hull devided by the heeling force of the rig when sheeted tight. A smaller ratio indicates a more overpowered boat.

50 x 6 x 7.0 x 60.0 x 2.00 => ratio 4.05
50 x 6 x 7.0 x 65.0 x 2.00 => ratio 4.28
50 x 6 x 7.0 x 70.0 x 2.00 => ratio 4.52
50 x 6 x 7.0 x 75.0 x 2.00 => ratio 4.76

50 x 6 x 7.0 x 70.0 x 1.75 => ratio 3.96
50 x 6 x 7.0 x 75.0 x 1.75 => ratio 4.17
50 x 6 x 7.0 x 77.5 x 1.75 => ratio 4.27
50 x 6 x 7.0 x 80.0 x 1.75 => ratio 4.38
50 x 6 x 7.0 x 85.0 x 1.75 => ratio 4.58

50 x 6 x 7.0 x 70.0 x 1.80 => ratio 4.07
50 x 6 x 7.0 x 75.0 x 1.80 => ratio 4.29
50 x 6 x 7.0 x 80.0 x 1.80 => ratio 4.50
50 x 6 x 7.0 x 85.0 x 1.80 => ratio 4.71


Other boats in the cat scene have :

109 x 6.78 x 11.12 x 2.35 => ratio 4.04 (Hobie 14 when not trapping; ratio is even higher when trapping ; 5.03)
104 x 6.40 x 8.64 x 2.15 => ratio 4.92 (Hobie Dragoon, 3.91 mtr length)
100 x 6.50 x 9.30 x 2.13 => ratio 4.40 (Paper Tiger, 14 footer no trapeze allowed by class)
118 x 6.10 x 9.20 x 2.13 => ratio 5.08 (Hobie wave, 3.98 mtr length no trapeze allowed by class)

An F16 sloop sailed 2-up and double trapped at 135 kg crew weight has a ratio of 4.13
An F18 sloop sailed 2-up and double trapped at 150 kg crew weight has a ratio of 4.33

Most other modern performance boats are in the range of 4.00 to 4.75 with respect to these ratio's, that is excluding the specialized singlehanders like the A-cats (2.65) and the single handed F16 (3.13) when either is sailed by a 75 kg crew. Note that both the A-cat and F16 1-up are beyond any doubt overpowered boats requiring skills to control. A 40 kg kid (average 12 year old) singlehanding on a F12 will have a ratio of 3.09 ! And he will share the same power-to-drag ratio of a 95 kg singlehanding skipper on a F16. Do we really want to see these toodlers doing 15+ knots while being all on their own and on the edge of control ?

The basic conclusion is that the heeling power (and power-to-drag ratio) of the F12 rig (when placed on a 50 kg platform) is pretty high compared to other designs. That is when sailed by an light to medium sized adult. And sailors seem perfectly happy to sail the Hobie 14, the Hobie wave, Hobie Dragoon or the Paper Tiger. In fact the dragoon is the true youth class < 14 years at the moment. I've sailed both the Hobie 14 and Dragoons as an adult and these are undoubtably fun boats. In fact, the loading per meter waterline length of the F12 with an adult on it is still south of the same ratio's for the other boats.

In fact, the Paper Tiger has the lowest value for this ratio of the alternatives and you'd have to load up the F12 to 156 kg to achieve parity. Achieving a total of 117.5 kg on the F12 (50 + 67.5 crew) achieves drag-to-sail power equality to the Paper Tiger when that boat is sailed by a 75 kg skipper.

The Texel rating system predicts very similar performance for either boat; both Hobie 14 and paper tiger are at rating 135 and the F12 with an adult is at 136. That is under 1 % speed difference around a race course.

In all honesty, I have never understood the large focus on kids when it comes down to the F12. It is far more suited to the crew weight range of 55 kg - 75 kg then for kids of 12 years of age (or younger) who have their mean at 40 kg and of which 85% is in the range 30 kg - 55 kg. Below 10.5 years of age and 95% is below 55 kg (their mean at 35 kg). Although, this also means that two kids crewing together on a F12 will be right back at the ideal weight range.

I hope I don't hurt anybodies feelings but there seems to be a persistant myth that hull length has a direct relation to the age of the crew. As for example that a F12 is for 12 year olds or younger, F14 and F16 for teenagers and F18 for adults. While in reality, the F12 (as it stands) is for best suited for teenagers, females and light males, F14 and F16 are for light to medium mixed crews or medium to heavy 1-ups and the F18 are for medium to heavy doublehanded crews including all male teams.

In fact, Phill Brander was right with his Blade F12, fitted with a 5.5 sq. mtr sail, as intended for 12 years old kids etc. This setup has a ratio of about 4.0 (for a 40 kg skipper and 6.0 mtr mast) and that is what I would put these kids through at maximum if they are to be solo sailing the craft.

To summarize a long explanation. I think the F12 could be a perfect adult (light to medium weigth) solo craft as long as the hulls are designed for the associated weight range and have sufficient freeboard for chop. The rig dimensions are fine as it stands and by making the rig light enough the diving of the platform shouldn't be a problem either. Of course, a rating of 136 (or only 20 minutes slower then a F18 or A-cat (rated at 101) that both completed a windward-leeward race in one an hour is really nothing to be ashamed off either. You will still be doing 11+ knots and beat the laser dinghy in the race by 15 minutes. The current 14 foot alternatives aren't going much faster at all. Ergo, The F12 power-to-drag ratio under an adult skipper is fine too.

Wouter

An interesting detail is that beyond 10 km you can't see the overturned F12 anymore even when standing straight up and the water surface is flat with a cristal clear sky. That is due to the round shape of the earth. The overturned craft will then be hidden by the horizon.

So any boat that can get away from you by that distance in a short time (15 knots => 21 minutes) is dangerous.

Wouter

Wouter

I hope I didn't scare everybody off with the long post.

I just wanted to elaborate that reconsidering the F12 as an adult boat might well be worth while. At least it appears that some redesigning of the hulls may lead to a very enjoyable craft for this target group. And that I suspect Gato is right in the middle of the weight band for that group.

Not saying that 14 footers are worse or anything.

Wouter

Wouter,

If the current F12 does not result in a proper startup boat for kids, the "kids cat" market niche will remain open for designs like Phil's while still F12 compliant. The development of the F12 class will give us the answer. It is perfectly possible that we see two trends develop within the class: one for performance (teens and adults) and one for simplicity (kids). The door should be opened for both ones.

I’m not scared away, and the figures fit and if I had children at the right age I agree completely, an adult can have a lot of fun with a F12 cat. The thing is, if you don’t have kids it is in my opinion better to extend the cat 2 feet to get a little bit bigger displacement to not be at the limit of what the boat can take (on the pics of the Tabby I’m at 75 kg, displacement of the Tabby 120kg, the highest of the three).
The DS12 has been sailing for one season, and it has not showed any signs of being dangerous even with crews with no experience from catsailing.
To make use of the potentials of this craft it takes quite a lot of skill. For a beginner its jus fun because its faster than the opti, but there is no chance you get close to the max without knowing what you are doing, and by then you also knows the risks.
To my experience the kids don’t like to go out alone as long as they don’t feel safe, and this cat looks more impressive than it is in the reality.

Adults can also fit into and sail optis and sabots, but that doesn't make it a good idea.

When the tornado was dropped from the Olympics one of the major discussion topics was development of a pathway into performance catamaran sailing starting with the kids. While there are a number of small cat classes around (arrows, arafuras, paper tigers), few were deemed suitable for kids only as a development class; too heavy, too much sail area, too complicated, too many adults already sailing them, too ugly.

The F12 can fit this niche very well, if the market desires.

Ahhh, come on !

That is a nice sound bite, but not really applicable to our situation is it ?

A F12 is a far cry from either an opti or sabot. The F12 is on a level with the Laser dinghy; same boat length, same mast height, same sail area and comparable or better performance. The F12's simply dwarf the opti and sabot in all these specs. Point in case, the F12 has over twice the sail area of the opti and almost three times the mast height. Not to forget its rig is light years head of the opti sprit sail. With respect to the hull/platform, well, the opti is halve the width and is also missing 5 feet of hull length.

Why would anybody compare the F12 to an optimist or a sabot ?

Hell, the non-foiling moths are significantly closer to the F12's in specs, so why not turn your sound bite around ?





Honestly, no personal disrespect intended to you Ncik, but your statement is a bit unhinged.

Wouter

I like this: a platform that is fast in skilled hands but slow (thus safe) in inexperienced ones. It spreads racing times according to skill, not luck, thus providing immediate response to learned skills.

Your spot on ncik
The F12 gathered so much momentum because it filled a gap in good promoted childrens catamaran. There are no end of small cats out there an adult can carry and rig. This is one of the very few that a 10 year old can rig and manoeuver to the water. If an adult came to my club looking for a relatively light, easy, safe cat to learn on I would recommend a Mozzie, F14 or an Arrow depending on their weight.
regards

Hey Jeff, If you'd ever seen me sail I doubt you'd be counting a Mozzie as easy and safe

Cheers

It was a good sound bite. hehe

But you haven't commented on the major point of my argument, that is filling a niche for a kids cat.

I thought I had but I'll just do it again.

I understand there is a desire to have a true youth catamaran. And in this case I seperate youth ( < 12 years) from the teenagers ( > 12 years). I actually agree with that part of the claim.

I'm not too sure, however, if the F12 is best suited to that role or whether it is simply pushed into that role because it is the best alternative available.

I do believe there is a significant push from a certain geographical area towards the latter part.

And I'm convinced the demographic data and ratios of the F12 design favor usage by the 55-75 kg crews alot more; especially when the F12 is a hiking boat rather then a singlehanded trapeze craft. This weight band is typically associated to 12-18 years olds and adult females c.q. bottom 60% of adult males.

I am really happy to hear from Gato that the expereinces so far have been promising, but I would love to know exactly the ages, weights and length of the people who have sailed her so far and see what percentage is truly a youth (kid). Not too mention the wind and water conditions. The age alone is not enough as some 10% of the worlds 12 year olds are above 55 kg and we all known Scandinavian people are the tallest in the world.


Now having said all this. I don't really care whether the F12 is used and promoted for youths (< 12 years) or not. Anything to keep them of the Laser dinghy and grow the ranks of cat sailors is a good thing.

I do however object strongly to promoting the F12 as exclusively youth oriented. I think Gato's experience that the parents were also after him for a F12 for themselvees as indicative. A F12 is a rather big toy and we all know how feeble the attention span of a youth can be. It is the parent that must justify the expenses and hassle of owning a F12. Being marketing savy means that it is alot smarter to include the parents in the F12 concept. Also for the youths as what youngster doesn't want to play being a grown up ?

I think the biggest mistake ever is to make a design exclusively for kids. It spells "training wheels" to them like nothing else. I remember that back in the day I was overjoyed when I got my first adult sized bicycle. It is a little too big for me but I soone grew into that. Which is another point with respect to F12's. Kids don't stay small for very long. If a design is optimized for < 12 years of age then most of them will outgrow the design in 2 to 4 years. For I really don't see many 8 year olds justify the purchase of a 3000 bucks F12. Note how 95% of the 8 year old kids (or younger) are shorter then 1 mtr and weight less then 35 kg. How would they right the craft ? How would they handle the rig even when on the trapeze they would match the power-to-weight and heeling-to-weight ratio of the 1-up F16 ?

I think it to be alot smarter to design the F12's in such a way that they are truly accessible to youths (if you lean that way) but don't spit them out as soon as they hit their teenage years because the hulls are under volumed.

The succes stories in both the Laser and splash/flash dinghy classes is that the youths get pulled into them at a young age but can stay there till way in their teens (possibly by exchanging the rigs for a smaller one). And Mom or Dad can take out the same boats for a ride using the some rig or the normal sized rig. This goes a long way in convincing Mom and Pop to lay down the money in purchasing the craft.

In short, "filling a niche" does not necessarily imply "being marketable" even when the reverse is true. Design for a niche that is too small or doesn't yet have their own purse is a design flaw. I think the Hobie product range for youths has proven that. Go anf take a look at their product range and see it you know any of these designs. http://www.hobie-cat.net/site_gb/?produits,produits It is the line-up on the lefts in red lettering. The only exception is the Hobie Wave but that boat is mostly sailed/raced by adults. Which give further weight to my proposal to at least ALSO cater for adults.

I also think there is another issue in the F12 class. If indeed we wanted a catamaran truly for youths then why are we fiddling about with single piece carbon rotating wing masts with spreaders, diamond wires, downhaul systems etc ? And not fully focussed on simple sleeved sails using glassfibre tubing for a mast and have only a kicking strap and mainsheet. The latter is heaps less expensive and 10 times more easy to ship. Right now the F12 is going the way of becoming the "A-cat for kids" ? An oxymoron if their ever is one.

I mean it the F12 is to be complete focussed on youths then marketability demands that it is dirt cheap to produce and even easier to transport. Right now the 6 mtr long mast that can not be broken down in smaller pieces is a serious road law infriction when it is car topped. At least in 80% of the developped world where there is enough money to buy a F12. How do I know ? Because I'm avoiding the police at all times when I car-top my non-collapsible 4.70 mtr tall landyachting / windsurfing masts. Most cars are only 3.50 mtr long overall. Having the mast stick out 1.25 mtr at the back and 1.25 mtr at the front will attract police attention for sure.

The "A-cat for kids" promises neither to be dirt cheap or easy (legally) transportable. Of course, if it is the same boat that Dad is using then the justification for getting the additional car trailer will be less of an obstacle. We all know that the difference between men and boys is the price of their toys.


Now summarizing the comments above. I say, lets get away from our focus of making the F12 "kids-only". It is neither a reasonable goal design wise nor smart market wise. Of course, doing a double "humm maybe" on these two points is a serious impediment to growing the F12's into a succesful class.

Lets expand the F12 concept to include all teenagers and small to medium adults. Seperate the class in a racing fleet below 12 years and above 12 year olds if we have too. Market the class to both fleets hard. If we are not getting the youths then at least we are attracting new adults to the cat racing scene and visa versa. Lets expand our market base that way and achieve larger turn-overs. The latter will reduce cost and grow fleets quicker which in turn means the F12 become progressively more attractive to new customers. INCLUDING YOUTHS.

Also there seems to be an adult based niche for these boats, many in this forum have said so themselves and also look at the Hobie wave class. These people y will provide " F12 beach heads" in various nations and regions from which the F12 class may grow internationally. Getting off the ground is the hardest part in any class. Being chavalier on that aspect is more then being "unwise". It may proof to be killing in the long run (ask Hobie corp with their youth boats) if we don't do that.

So get the marketabilty right for the F12 and then adjust the design so it does fill the desired niche for <12 year olds as well. The difference right now is just putting enough volume in the hulls. What is the penality in that ? From the F18 and F16 classes we already known that you can't really over do it with respect to hull volume. Too much volume is nowhere near as bad as too little hull volume. Now the < 12 kids won't notice some 3 % performance loss due to designing the hulls to max 150 kg displacement. They got more then enough power in that 7.00 sq. mtr. by 6 mtr rig to overcome it.

Wouter

150 kg displacement! At 120 kg it starts already to look a little bit poofy.

The difference is just 12% more width and 12% more height in the hulls below the water line.

And the Tabby isn't very poofy if you have seen the newest F18's like the Infusion and Hobie Wildcat.

Poofy is the new fashion !

Wouter


WOW ! I made a post under 4 phrases, did you see that !

Can't...read...whole...post, however I did skim over it.

My definition of a kid is under 16, so we have an overlap in our opinions there. Under 12's I would suggest sail the F12 2-up, it is too big a rig for a 40kg skipper on their own.

An interesting read...
http://www.optiworld.org/ioda-faq.html

Spot on again Ncik
Your right about the regional use's for the F12 Wouter and I would encourage you to keep promoting to the adults. For me the F12 is perfect for our club to get kids into cat sailing.
My 8yo can and doe’s sail an 11ft cat no worries when there’s not much wind, no waves and he’s closely supervised by adults at all times. He doesn’t go far but has a great time. My F12 is for my experienced 12yo girl to sail 1 or 2 up so will have the added benefit of a jib and traps. My 13yo already sails the Arrow 1 up with the jib. Don’t underestimate the ability of the normal kids out there sailing nor they’re apparent average weight (by definition there are hardly any on the average). Most of the youth attracted to this cat will have been sailing dinghy’s for a while and will feel quite safe to see how hard they can push it.
You can make a bigger and puffier with higher buoyancy version for the adults and I would encourage you to do it but you shouldn’t plan to tinker with the minimum class weight’s exc to make your version more viable to adults at the expense of the younger users. There is no better youth friendly cat available in the world at the moment because its super light, has the safety of a short light boom with high aspect rig, minimum controls, easy to make and repair, modern looking and can be adapted to suit different regions.
Well done to the designers that have put these kid cats together
I’ve started to assemble the DS12 with the kids and I think you can say its child play