Hi Guys,
sorry for the absence but Ive been busy and I moved to another town.

Recently met a guy who is interested in producing the round bilge version of the F12 by rotomolding. At this time we are looking to see if there is any interest in a finished boat that at best guess will be within 1-2kg of the minimum weight and will sell for approximately $4000 USD (thats landed in the USA (Longbeach, LA ?) but not including taxes. Sails will be made in NZ, boards, rudders and rudderhead will all be carbon, mast will be aluminum wing section (rotating) and SS rigging. If we can get tentative orders for 25 to start with, then the project will proceed.

Your comments and/or interest will be appreciated.

Cheers RG

It's just great, Im checking around a little bit here in Finland to see if there is an interest big enough

RG where are you sourcing mast extrusions from? I might be willing to kick in to the order to minimise the upfront cost. I assume you've been told you have a minimum no of kg to order (usually about 200kg)

Scarecrow...we'll have our own dies and will get batches extruded locally....would welcome you taking a few off our hands when the time comes :-)
Cheers
RG

Count me as one boat.

Depending on total cost (freight to Asunción could be expensive) it will be one or two boats.

Will talk to other people who could be interested during the weekend.

I bet you could lower the price and weight by choosing the self standing mast version.

Luiz

Weight = no, price = yes.

Full unstayed rig will weight at least 10 kg and at max 15 kg. This includes the (collapsable) mast, boom, sail and battens. The difference in weight depends a little on the tube diameters you're using.

Currently I'm using a 45 mm ounter diameter lower section on my class 5 landyacht and it works very well. It is better then my older 50 mm outer diameter mast. The sail pumps very nicely with the gusts and the car is feels very fast and direct with it. Even in the lower windrange it pulls quite well. However, lower wind ranges for landyachting means a force 4 wind. 10-15 knots. The total sailarea is however only 5.3 sq. mtr. A larger 6.0 sq. mtr. sail is available off-the-shelve for this mast as well. That one should give you some more power in the lower wind ranges.

This mast (complete) costed me 127 Euro's excl. taxes and shipping was (relatively) inexpensive as well because the large mast section was only 2.70 mtr. The whole mast is 5.5 mtr tall and comes in three sections. I'm using a 1:5 mainsheet purchase system on my class 5 and the mast handles these loads perfectly. Without going into details, this shows that the thinner mast could mostl likely be be used on the a F12 as well. The main advantage is of course the fact that the rig can be fully collapsed and that makes it alot less fragile in shipping and cheaper as well.

The "heeling moment" of either mast layed horizontal is about the same (stayed, unstayed) unless the stayed mast is tapered. However, I greatly suspect it isn't as the proces making these stayed masts is extrusion and that allows only constant crosssection tubes. The unstayed mast is off-course tapered by definition.

If I had a platform I would simple put that rig on it for initial testing purposes.


For what that was worth !

Wouter

Simplicity and ease of rigging = yes.

Doesn´t the self standing support alleviate hull an beam stresses enough to require less reinforcement, resulting in less weight and cost?

Also, doesn´t the more flexible self standing mast make the boat easier to handle, even if a bit slower?

Anyway, whatever the setup I'll buy at least one.

Yes. Especially the bows can be build lighter although some of that advantage can also be had by installing double forestays.

The main benefit appears to be that the hard points halveway between the beams is a lot better position to lead the loads to then some bow bridle hard point. Especially when the daggerboard bulkheads are in the same neighbourhood. This allows a designer to use the same reinforcement for more then 1 purpose. And because the trampoline is TENSIONED the strut forces trying the push the hulls apart are significantly reduced. That is one of the beauties of the depicted unstayed mast design. The other is the almost complete negation of mast step loads on the mainbeam, voiding the need for any dolphinstriker. In fact the mast step pulls the beam UP slightly instead of pressing it down.

I haven't done a full comparison of both proposals so I don't really know the net result in the way of overall weight etc. But you'll be surprised at how elegant the depicted unstayed rig is in the way of construction and loads.

Personally, I really like to overall simplicity and clean look. Two of the things I also like about the Laser dinghy.





Only when designed right. That is one thing I learned with my 4 individual class 5 rigs (4 sails and 3 masts). The newest mast and sail that I bought together as a set are noticeably better in feel and speed. They are just a joy to sail. But the same can be said for any mast and sail combo, also of stayed rigs.

I don't really know if the unstayed rig will be slower. For one thing it may turn out that going dead downwind is faster on the F12 then gybing downwind. Just as with the H16. The unstayed rig can be boomed out completely; not possible to the same extent with the stayed rigs. It is hard to predict which will be the faster mode. But I can be said that the unstayed rig may well be faster and more attractive then many are giving it at first glance.

I always remind myself of the Class 5 landyacht example (unstayed rig) when compared to the Class 3 (stayed rotating wingmast rig with more sail area). Over the last 20 years the class 5's have become so fast that it is scaring away to lesser pilots and it is not at all far off the pace from the King class that is the class 3. The class 5's already have left the One-Design Standart class (unstayed but more area and camber inducers) in their wakes for quite a while. Such was the development of that very simple sock sail principle without camber inducers on a discretely tapered unstayed mast made up from plain alu tubing.

For my own use, I'm very willing to accept any performance loss (if any exists) because of the other advantages. I trailer about 3 to 4 landyachts each time I go and the class 5 is by far the most practical craft. So easy and quick to rig and such an impressive performance that I feel absolutely no desire for a more performant rig. And that was the experience of a large group of class 5 sailors and they started the simplified Promo class using cheaper and commonly available components. This reduced the overall speed somewhat, but that was also the intent. Screaming over a rough beach at 60+ mph (100+ kph) is darn scary at times. Much more then doing it at 50+ mph (85 kph). Mind you the rigs were left unaltered ! All the speed loss comes from the much smaller wheels and thicker tires. Actually these also allow you to drive over less compact sand and entlarge your course.




Best of enjoyment !

Wouter

Hi Luiz,
I'll count you in for 1, the other we can talk about later if required. We are now up to 8 of the 25 we need to go ahead with this.
Right now the rig will be a conventional stayed rotating mast with boom as this is what the majority want, but if that changes then we'll cater to the need.

Cheers
RG

Luiz and others,

The 45 mm unstayed mast has a total length of 5.50 mtr and weight of 6.7 kg. The sail with battens is 3.0 kg. The centroid of this mast alone is located at 2.2 mtr from the base and that is 0.55 mtr less then the centroid location of any prismatic (extruded) mast (of same length = 5.5 mtr). Meaning that if both masts weight the same then the unstayed mast requires less righting moment. About 3.65 kg less for a person of 1.65 mtr length.

So basically unstayed mast + sail is 10 kg, with a better weight distribution.

Actually, I believe that is about the same weight that a stayed mast made from extruded aluminium would be as well. Of course their will not be any weight difference between the sails, only a shape difference. The same for boom and sheet systems.

I do suspect however that it is alot easier to produce a carbon version of the unstayed mast then for the stayed rotating wingmast. Afterall, the unstayed mast is nothing more then a set prismatic round tubes that are slid into eachother and I believe such carbon tubes can be ordered from a number of sources. The longest tube is only 2.5 mtr long.

Wouter

Wouter,

The main difference for me is storing with the other cats in the mast-up area outside, or storing with the Lasers and Optis under roof. Ease of rigging and transportation make a difference too.

Still, whatever the configuration I'll buy at least one.

Grob said he would try different rigs on his rotomoulded F12 so we will maybe get an opibnion from him once he has been out sailing.

Hows the rotamoulded F12 coming ?

after a long wait, the company that will produce the rotomoulded F12's finally has all its money in place and will start shortly. To date all the hull moulds have been milled, still have to do the centerboards and rudders, the carbon mast moulds are done also. Their goal is to have the first 20 boats done by Xmas and have their first regatta in NZ around the same time. No info on prices yet but will post that when I find out what its is. Based on Murphy's law I wouldn't expect them to make the Xmas deadline, but you can always hope.

On our recent trip to the Lake Eyre regatta at Lake Killamperpunna Enya T boned another nearly new cat and damaged both the bows on her timber Arrow. When she told me what had happened she said lucky the other boat was a plastic boat and she just bounced off it with no damage to the other cat. Its a good add for roto moulded.

Thanks very much, sounds awesome .Hope Murphy is wrong this time!

If you're willing to sell parts separately, I may well be interested in a mast + a set of foils. My current plan for a mast is an MG14/NS14 section, but they are not what I would describe as appropriately priced (and I don't really want an ally main section with a carbon tip).

I was going to make my own foils, but if there is a design with an off-the shelf solution I'd rather use those, especially as it means I'm more likely to be able to swap for someone else's if required.

Sounds great RG, I think this is a very good thing and in one way the only way to bring the F12 forward.

As usual things go much slower than you want, but here are a couple of pics (not good ones unfortunately) of the finished plugs...I'm thinking they'll be hard pressed to be in the water by Christmas but it will happen eventually :-)

They look great! Keep us informed.
Are you involved in the project or construction of wings for the new AC cats in NZ?

Love what you are doing for the beam attachment...I am planning to do something very similar for my F14 Project...nice to see it put into practice. Wonder why it is not a more common solution to the beam to hull attachment issue...seems like the most logical method to get a really stiff connection.

As news or progress happens I'll post stuff. Not involved in the AC Cats but I do have a 3 boat C-Class project in the works, so far we are still playing with hull shapes and doing a little CFD work, haven't touched the wing design yet.

While it can be stiff, it is not the reason I had for doing it. The beam tubes need a lot of plastic around the Aluminium inserts inside the tubes and this shape nicely funnels the powders down there as the mold rotates so both sides of the inserted tube are covered. After molding we bore out the inner plastic a bit to get a perfect fit for the beam tubes, 1 bolt at the ends mounted horizontally holds the tubes in the seats.

Given the constraints of the current draft rule for the AC cats, the C Class project seems to be a lot more interesting, even if less visible.

I guess the Vudu will be even more important, but only time will tell.

I was under the impression that Rotomolding used metal molds...how do these plugs factor into the process? Wouldn't this project have been a perfect candidate for direct milling of a metal mold from CNC? Or are these plugs going to be used to create some type of casting? from which the final mold will be constructed?

Much as the common wisdom says that you need aluminium/or metal molds, they aren't the panacea that many believe them to be....they can pit just like any other mold and then you have to silicon fill the pits to maintain surface finish.
We will be using composite molds with a resin system that has a heat distortion temp that's very close to the molding temp and experience has taught us that those molds should be good for about 600 hulls....if we ever get to that many F12's....I'll be both surprised and delighted :-)

Interesting...What type of resin has a heat distortion temp that high? Or does your particular rotomolding technique use a type of thermo set plastic that works at lower temp? It is very cool that you can side step the expense of Metal molds...Would it be safe to say that the viability of the rotomolding project pivioted on the cost savings of the composite molds VS Metal molds? Hull plug looks awesome....

Seeker, there are epoxy resins specifically designed for high temp use. Typically they require a long hot post cure to temperatures beyond where they will operate.

Just out of curiosity, what kind of working temps does the mold have to funtion at for this type of rotomolding?

Seeker,

it depends on the selected plastic but they can vary anywhere between 150 and 300 degrees C (302 and 572 degrees F) IIRC the Tooling resins I've used for high temp carbon moulds go up to about 220 degrees C (we were cooking to 180 degrees C and 7 atmospheres of pressure).

Example

I found this boat while surfing around the internet. It is rotomolded and looks very similar to f12, except for having more metal than a Honda Civic, lol. You'll see what I mean when you see it. Has very similar sail plan and there may be bits and pieces that translate to f12 boats. Available in France and UK. Built in France where catamaran building is govmnt subsidized to create exports.

http://www.windkart.fr/index.php?lang=en