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#134967 - 03/06/08 08:26 PM DS12 ***  

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Thats right folks my Formula 12 design finally has a name. from here on it will be the DS12.

[Linked Image]

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Last edited by Scarecrow; 03/06/08 10:19 PM.
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#134968 - 03/09/08 12:20 PM Re: DS12 [Re: ]  
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Pics of one under construction will come soon <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

#134969 - 03/10/08 01:11 AM Re: DS12 [Re: Gato]  
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So kids, get the materials and get ready, the first building lesson will come tomorrow. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

#134970 - 03/10/08 09:51 AM Re: DS12 [Re: Gato]  
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So the first lesson is up. It will propably be rather boring for most of you, but if we combine our ideas we will maybe end up with a good manual how to build a DS12.
http://www.gust.ax/gallery/2008-02-10/08-03-10/

#134971 - 03/11/08 07:11 AM Re: DS12 [Re: Gato]  
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What kind of rig are you going to put up there ?

If you are going to home make your mast anyway then the unstayed version is even more attractive because of the high stiffness of carbon cloth.

Wouter


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#134972 - 03/11/08 08:11 AM Re: DS12 [Re: Wouter]  
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It will be the stayed rig Scarecrow designed with the possibilities it gives for ex. to sail two up and even to use a spi (have not asked him for that yet <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />).
Got the first sail sponsored by North Finland <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

#134973 - 03/11/08 12:59 PM Re: DS12 [Re: Gato]  
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#134974 - 03/12/08 06:12 AM Re: DS12 [Re: Gato]  
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Wow, this is excellent! <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />


"House prices have risen by nearly 25 percent over the past two years. Although speculative activity has increased in some areas, at a national level these price increases largely reflect strong economic fundamentals." Ė Ben Bernanke Ė 2005
#134975 - 03/17/08 01:44 PM Re: DS12 [Re: Buccaneer]  
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#134976 - 03/17/08 03:41 PM Re: DS12 [Re: Gato]  

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Thanks Gato,

keep up the good work.

#134977 - 03/18/08 01:44 PM Re: DS12 [Re: ]  
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Number five is up... <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />
http://www.gust.ax/gallery/2008-02-10/08-03-18/

#134978 - 03/20/08 12:03 AM Re: DS12 [Re: Gato]  
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#134979 - 03/22/08 08:55 AM Re: DS12 [Re: Gato]  
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Good one, thanks for the effort! <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />


"House prices have risen by nearly 25 percent over the past two years. Although speculative activity has increased in some areas, at a national level these price increases largely reflect strong economic fundamentals." Ė Ben Bernanke Ė 2005
#134980 - 03/22/08 12:55 PM Re: DS12 [Re: Buccaneer]  
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Some more pics, sorry no text...
http://www.gust.ax/gallery/2008-02-10/08-03-24/

#134981 - 03/31/08 01:03 AM Re: DS12 [Re: ]  
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Quote
Thats right folks my Formula 12 design finally has a name. from here on it will be the DS12.


what is "DS" short for ?

#134982 - 03/31/08 01:33 AM Re: DS12 [Re: Questioner]  

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I was wondering when someone would ask that...

Free set of plans to the first person who guesses.

#134983 - 03/31/08 03:56 AM Re: DS12 [Re: ]  
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"dead simple"

Wouter


Wouter Hijink
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#134984 - 03/31/08 07:03 AM Re: DS12 [Re: Wouter]  
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"doing something" as opposed to talking about it <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

#134985 - 03/31/08 10:08 AM Re: DS12 [Re: ]  
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Quote
I was wondering when someone would ask that...

Free set of plans to the first person who guesses.
Dark Side


John H16, H14
#134986 - 03/31/08 12:05 PM Re: DS12 [Re: ]  
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dead set


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#134987 - 03/31/08 01:07 PM Re: DS12 [Re: Mark P]  
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#134988 - 03/31/08 04:36 PM Re: DS12 [Re: _flatlander_]  

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Quote
Quote
I was wondering when someone would ask that...

Free set of plans to the first person who guesses.
Dark Side


That wasn't so hard now was it. Where do you want me to send your plans? Of course now you own a set of plans you're obliged to build a boat.

For the record while the DS does stand for Dark Side (in my head anyway) it is a DS12 not a Dark Side 12.

When I get around to building a boat it will be called Ruby Gloom . Make sure you have your speakers turned on when you follow the link. I discovered this cartoon while babysitting my 3 year old niece last month. Some of the music is great.

#134989 - 03/31/08 04:46 PM Re: DS12 [Re: ]  
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I hope you didn't let the 3-year-old watch that! <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" /> It sure scared the heck out of me. I'm probably going to have nightmares.

And why would you name a boat for kids "Dark Side"?
Well, maybe you are not building this boat for kids.

#134990 - 03/31/08 05:00 PM Re: DS12 [Re: Mary]  

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Mary read in full, the boat is not called Dark Side 12 , its called DS12.

Next time you watch a feature length cartoon (Shrek etc) take note of the layers. Typically their are two levels of story, one which follows the basic fairy tale for the kids and another that is full of innuendo for the adults.

Unlike a lot of TV cartoons (from bugs bunny through to the crap that is produced these days) Ruby Gloom is very valuable viewing. The key theme behind the series is that no matter what people look like, they are all the same on the inside. Compare that to the Brothers Grimm and their lessons. "If you go walking in the forest you'll either get eaten by a witch or a bear" "No matter how nice your new step mother may appear she is actually evil and either wants you dead or to be her slave". I think I'll take Ruby over Disney.

#134991 - 03/31/08 05:26 PM Re: DS12 [Re: ]  
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Doesn't matter. You have already said DS is short for Dark Side, and I think that is bad juju for a sailboat, whether for kids or adults.

And I don't agree with you about that video. It's just plain creepy. Especially with that music. <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

#134992 - 03/31/08 05:37 PM Re: DS12 [Re: ]  
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It sounds like Star Wars.... <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />


Florin
#134993 - 03/31/08 05:44 PM Re: DS12 [Re: Mary]  
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I went to some of the links on the web site (at my own peril), and some of them are even creepier.

#134994 - 03/31/08 08:03 PM Re: DS12 [Re: ]  
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Quote
Quote
Quote
I was wondering when someone would ask that...

Free set of plans to the first person who guesses.
Dark Side


That wasn't so hard now was it. Where do you want me to send your plans? Of course now you own a set of plans you're obliged to build a boat.

For the record while the DS does stand for Dark Side (in my head anyway) it is a DS12 not a Dark Side 12.

When I get around to building a boat it will be called Ruby Gloom . Make sure you have your speakers turned on when you follow the link. I discovered this cartoon while babysitting my 3 year old niece last month. Some of the music is great.
No Chris, not hard at all. Very happy to have the plans AND USE THEM, I've been aspiring to build an "F12" of some sort for more than a year now! Thanks again <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" /> I've sent you a PM.

Mary,

From the Ruby Gloom site
Quote
Love is the main ingredient of friendship (a little sugar makes it even sweeter)
I like their "twist" <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />


John H16, H14
#134995 - 04/01/08 03:15 AM Re: DS12 [Re: _flatlander_]  
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Mary would probably prefer; DS = Demi-sec (medium sweet)


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#134996 - 04/01/08 05:08 PM Re: DS12 [Re: Mark P]  

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Double Sweet
Down Sugar

or course the real translation is










































Dumb Scarecrow, just don't tell anyone

#134997 - 04/03/08 07:48 AM Re: DS12 [Re: ]  
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So, the hulls are about ready to be painted (yes I know I'm behind on my blog), so any ideas for the colour for a cat for the kids (still I think it will be difficult to get daddy of this thing...)
Normally all my boats are deep green...

#134998 - 04/03/08 08:13 AM Re: DS12 [Re: Gato]  
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Gato, you need to lure in somebody from an art school there and give him freehand to put some colour and graphics on the boat.
These guys and gals are usually excited to do something like that. (I would be)

Just a wild thought.


Florin
#134999 - 04/03/08 09:29 AM Re: DS12 [Re: isvflorin]  
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Wild but not bad, see what I can find...

#135000 - 04/03/08 10:49 PM Re: DS12 [Re: Gato]  
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Lesson number nine is up. Will be sitting on a ferry all Monday and hopefully get some time were there is not a lot else to do so with a little bit luck there will be more after that.
http://www.gust.ax/gallery/2008-02-10/08-04-04/

#135001 - 04/07/08 10:52 AM Re: DS12 [Re: Gato]  
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Some more pics and a little text. There are more to come the blog is still dragging behind.
http://www.gust.ax/gallery/2008-02-10/08-04-08/

#135002 - 04/08/08 09:59 AM Re: DS12 [Re: Gato]  
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#135003 - 04/08/08 10:49 AM Re: DS12 [Re: Gato]  
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#135004 - 04/09/08 07:43 AM Re: DS12 [Re: ]  
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Greetings Gato,
I have a question, what type of glass are you using for attaching the chain plates.
http://www.gust.ax/gallery/2008-02-10/08-04-09/p3280013-640.jpg

Thanks,

Les


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#135005 - 04/09/08 09:27 AM Re: DS12 [Re: lesburn1]  
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On the DS12 I used 2x400g BX +/- 45 deg on hull and 1x400g BX +/- 45 on top. Stil this is a little bit overkill, the same layers of 200g plain would do the job.
Still the far best solution if you have vacuums equipment is to make everything in carbon.
I made that on my Mini 650 and I have been lifting the boat from them(800kgs).

Last edited by Gato; 04/09/08 09:28 AM.
#135006 - 04/09/08 12:41 PM Re: DS12 [Re: Gato]  
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If somebody is up for a little metal work: http://www.gust.ax/gallery/2008-02-10/08-04-12/

#135007 - 04/10/08 07:31 AM Re: DS12 [Re: Gato]  
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#135008 - 04/10/08 11:28 AM Re: DS12 [Re: Gato]  
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I thought about chain plates of carbon on beachcats, but I worry about wether the weight savings are worth it and if they can stand the shock loads?

Great work on the mastfoot and striker! I dont have any welding equipment and have never welded stainless either so I'll think about a way to do something similar without welding. Thanks for sharing!

#135009 - 04/10/08 10:23 PM Re: DS12 [Re: Rolf_Nilsen]  
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I decided to go for a ss tube because that is no problem to weld with ďnormal equipment, alu is an other story. Guess you got a drawing from Phill, the problem with that one is that you have to drill a big hole trough the bottom of the beam and itís there that you would need the material..
Guess it would work if you make the mast foot out of a M12 threaded rod going down all the way trough the strap, putting a spacer inside the beam and making the possibility to adjust the tension by one nut on each side of the strap. Itís not the most beautiful setup and a little bit heavy.
Had been expecting a lot more hints coming in on this thread. But guess it will come when people will see what the art school of Turku can do if they take on the painting job, then everybody can get emotional...
Can give no guarantees for the carbon chain plates, but if they resisted on Idec when Francis Joyon made his record run around the world why should they not resist on a beach cat?

#135010 - 04/11/08 03:38 AM Re: DS12 [Re: Gato]  
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Very nice metal work there Gato !

With respect to the hole on the bottom of the beam. Because of the dolphinstriker and upward pretension of the beam you don't really need the material there. The beam is mostly under direct compression and with the right upward prebend the beam bends down under sailing loads to almost hardly any bending stresses. This is why the "tube through bottom of mainbeam" as the dolphinstriker pin is such a common way of fitting. It is simple, does the job very well as it transmits the loads directly from the pin to the mast voet and it doesn't crack up or break even after years of usage. There is not much point in doing it any other way.

Wouter


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#135011 - 04/11/08 03:47 AM Re: DS12 [Re: Wouter]  
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Maybe this is a stupid question with a straightforward answer, but - why not use ss wire for tensioning the beam ? Or thin rod ? Round section material is best for tension loads, I assume the flat strip setup is used because it "cuts" the waves better than steel rod ?Or maybe adds rigidity in the horizontal plane ? But how large diam. should be enough for the tension there ? 5-7mm ?

I'm asking this because the flat ss strip looks too much extra material to me, for the tensioning purpose.

Last edited by isvflorin; 04/11/08 03:50 AM.

Florin
#135012 - 04/11/08 03:54 AM Re: DS12 [Re: isvflorin]  
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I think it is a good question, but also expect a good answer <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

#135013 - 04/11/08 05:57 AM Re: DS12 [Re: Rolf_Nilsen]  
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On The Pixie 14 the setup is with a wire. I'm maybe stupid like h.. but I hade tought that the dolphinstriker was there to take the downward forces (compression) that will occure in the mast, and then to my simple thinking the underside of the beam is taking more and you need less cross section in the strap if you don't drill a 25mm hole in it. It's also stupid in my opinion to drill a hole in the strap, because you have to use a bigger cross section, to compensate the loss of material or can that also be canceled?
I'm going with Florin, there is no need to add more weight than needed.

Last edited by Gato; 04/11/08 06:00 AM.
#135014 - 04/11/08 06:13 AM Re: DS12 [Re: isvflorin]  
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The answer is stiffness.

You want the mainbeam setup to be very stiff in the vertical plane. The more material in the dolphinstriker the stiffer the mainbeam setup. You can get alot more material (stiffness) in say 30x3 SS strip then a 7 mm ss rod. About 2.34 times as much. 7 mm SS wire is less stiff then a 7 mm rod, so you loose even more here.

Additionally there is hardly any difference in tension resistance between a round second and a flat rectangular one. Also it is alot easier to fit a flat strip to the underside of the mainbeam then a round rod; same for fitting the dolphinstriker pin to the strap. It is easier to bend a flat strip into a V-ed shape then a thick round rod and last but not least a frontal area of 3mm by 1500 mm is significantly less then 7 mm by 1500 mm when impacting with 1000 kg/m3 water. And and I forget that a flat strip keeps the pin in place in the horizontal plane were the rod and wires will do so muhc less. In fact the pin on my boat is not even secured in the beam. It was just slid in and there is no hole in the strap either, just a piece of metal welded horizontally to the end of the pin adjustement threading. This T-ending actually secures the pin to the strap and when under tension it can not move at all. Best part is that this setup can be taken apart in mere seconds and I have done so. Just turn the screw to detension the pin, move the T-ending up and turn it through 90 degress, angle the pin and slide the whole thing out of the beam.

In fact there is no good scientific reason to use round rods; only guts feelings to that extent.

Wouter

Last edited by Wouter; 04/11/08 06:17 AM.

Wouter Hijink
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#135015 - 04/11/08 06:32 AM Re: DS12 [Re: Gato]  
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Quote

I'm maybe stupid like h.. but I hade tought



No, you are not stupid, you've just made a modelling error. In fact you overlooked part of the system.

When the rig is loaded the mast presses down on the mast foot which in turn pressed down on the beam AND the dolphinstriker pin. In turn the pin presses down on the dolphinstriker strap. The strap is ALOT more resistant to being pressed downward then the beam is. In fact the strap takes care of the vast majority of the mast foot loading; in the order of 75-90 % if the beam is not prebended upward initially. The strap comes under tension to resist the downward loading of the mast (compression in pin) and this results in almost equal compression forces in the mainbeam. The latter are transmitted from the strap to the mainbeam via the bolts securing the strap to the mainbeam near the hull.

This is commonly accepted stuff so far.

Now if the beam was perfectly flat before the mast being stepped then the beam will bend downwards when the rig is loaded up just like the D-striker and thus experience bending stresses. These bending stresses are highest on the top and bottom of the beam and typically an engineer want material in these places to limit these stresses.

That is your reasoning.

My reasoning and one that is commonly applied on cats is as follows.

If the d-striker strap is pretensioned upward before the mast is stepped then the mainbeam will straighten out first before being bend downward under a loaded up rig. Of course a straight beam can not experience bending stresses, only a curved beam can. So in effect if we give the beam the right amount of upward prebend we can lower the bending stress significantly under a fully loaded up rig. If the prebend upward is the same as the downward displacement of the V-tip on the D-striker under max sailing load then the bending stresses in the mainbeam are perfectly zero and the beam will ONLY be under compression loading. This latter situation is not always used in reality as it is advantagious to leave some bending of the beam but that is another topic. But I can give you some insight into the reasoning. The D-striker puts the beam under compression stresses and a slightly downward bending beam will see tension stresses on the underside of the beam. By careful selection of the upward mainbeam prebend you can have these two cancel one another out completely. In that situation it won't matter one bit how large the whole on the bottom as that part of the beam won't experience hardly any stresses at all ! The trick is to find the optimal average setting for a range of sailing conditions (rig loading)

And that answers the question

Wouter

Last edited by Wouter; 04/11/08 06:36 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#135016 - 04/11/08 06:59 AM Re: DS12 [Re: Wouter]  
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Thanks for the answer Wouter,
Actually your answer makes me think more into it (trying not to..)
If you say flat strip is used for rigidity in the VERTICAL plane- well I don't understand why flat strip is more rigid than rod, I understand why flat strip is more rigid than rod in the HORIZONTAL plane, but why VERTICAL ?

To my understanding mainbeam rigidity is given by the stiffness of the Alu cross section and the aditional compression put into it by the straps @ tensioning pin. The longer the dolphin striker pin=more rigidity (considering the apropriate tensioning strap)

Considering that , the ultimate role of the straps is to handle tension loads, whatever it's cross section. Further more , a 1m long 7mm diam ss rod is much more rigid than a 30x3mm , same lenght ss strap - in the plane perpendicular to the 30mm side. Of course the opposite occurs in the other plane.

I understand it is easier to fix the strap to the Alu profile, but you can use an end fitting for the rod.

A 30x3mm ss strap has 90sq mm of cross section, while a 6mm diam rod has 28sq mm of cross section, hence lighter.

More to it: when the boat nosedives and the Dstriker enters the water it reacts pretty much as a wing, opposing resistance for the boat to resurface, while a rod has much less resistance for resurfacing.

Is this like a MythBuster case ?
6mm diam rod can take a lot of tension, we designed stair ramps hangin' from ceiling, supported by thin cables...
don't like the math of it but I assume even 5mm rod should do it. The tension in the rod should be higher or least equal to the compression and dynamic forces that the mast exerts on the beam.

Wouter can you clear this out for us, or at least explain where am I wrong, may be missing something.

by the time I wrote this you already wrote more to it.

Last edited by isvflorin; 04/11/08 07:04 AM.

Florin
#135017 - 04/11/08 08:27 AM Re: DS12 [Re: isvflorin]  
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Typed up a reply and then it turns out the time-out had passed and I lost everything.

I don't feel like retyping it so ...

Sorry,

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#135018 - 04/11/08 09:10 AM Re: DS12 [Re: Wouter]  
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Wouter,

it is not the first time I hear about this problem from you (and others). I use Firefox at home, and when I go "back" after recieveing the timeout notice Firefox remembers what I wrote and fills out the text field. If it is possible for you, I think you should give Firefox a try.

#135019 - 04/11/08 09:19 AM Re: DS12 [Re: Wouter]  
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Quote

Typed up a reply and then it turns out the time-out had passed and I lost everything.

I don't feel like retyping it so ...

Sorry,

Wouter


Shall I have a go....

The strap is working mostly in tension not bending so its orientation (vertical or horizontal) is irrelevant, its stiffness is proportional to its cross sectional area only.

So as you say "A 30x3mm ss strap has 90sq mm of cross section, while a 6mm diam rod has 28sq mm of cross section" so the strap is stiffer.

Does that make sense?

All the best


Gareth

#135020 - 04/11/08 10:17 AM Re: DS12 [Re: grob]  
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Not really...

Considering the straps alone, not fixed to the beam :
stiffness is different for the 90 and 0 degree plane on the rectangular cross section strap, while for the rod stiffness is equal in both planes.


1. If the cross section area is enough for the tension loads (and a safety factor) what relevance has the cross section shape (other than ease of mounting to the beam) ?
2. The flat strap adds rigidity in the horizontal plane but I can't see how it adds higher rigidity in the VERTICAL plane compared to rod (again -as long as the cross section area is enough for the loads).

SS has a tensile breaking strength of 5300kg/sq cm
that means a 6mm diam rod can withstand aprox 1500kg of tension or 147Mpa. Is it enough ?

Come on guys, need answers for this.

Gareth - stiffness is related to material distribution in a given cross section, not necessarily higher than rod for a certain cross section area. For example for a given cross section area you can draw several shapes with different stiffness manifested in different planes. The idea is that the whole thing (beam+d striker and straps) should be stiff.

And another thing, am I on topic ? Should we put this on the Homebuild forum ?

Last edited by isvflorin; 04/11/08 10:43 AM.

Florin
#135021 - 04/11/08 12:55 PM Re: DS12 [Re: isvflorin]  
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isvflorin,

You are getting confused between bending stiffness and stiffness in tension.

What you are doing wth this arrangement is creating a truss, The vertical member is in compression, and the straps are in tension not in bending. Stiffness in tension is related purely to its cross sectional area.

All the best

Gareth

#135022 - 04/11/08 01:06 PM Re: DS12 [Re: grob]  
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A dolphin striker is a trussed arch as shown in figure E

[Linked Image]

from the page http://mysite.du.edu/~jcalvert/tech/truss.htm

Gareth

Last edited by grob; 04/11/08 01:26 PM.
#135023 - 04/11/08 01:26 PM Re: DS12 [Re: isvflorin]  
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Quote

SS has a tensile breaking strength of 5300kg/sq cm
that means a 6mm diam rod can withstand aprox 1500kg of tension or 147Mpa. Is it enough ?



The design of the striker does not revolved around strength but rather stiffness.

A 4 mm wire can take the loading but won't add enough stiffness to the beam in the vertical plane. This is turn MAY allow the beam to bend to much (even with prebend) and raise the bending stresses in the beam to such a level that the beam may indeed crack or rupture. Without the beam taking the compression of the striker the whole setup fails and folds up downwards leaving the mast unsupported and destroying the whole craft in the proces.

So strength calculations alone are not sufficient one needs to include the stiffness portions as well. especially when looking at sail behaviour. A flexing mainbeam playes havoc with mainsail sheeting and trim.

That is the short version of my earlier posting

Wouter


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#135024 - 04/11/08 02:03 PM Re: DS12 [Re: Wouter]  
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Ok, my last q ?
So basically you need to over dimension the cross section of the straps to get more stiffness in, like being much above the breaking limit where the strap does not oscillate/vibrate from dynamic loads ? Well in that case, considering the same cross sectional area what is the advantage of the rectangle cross section. Don't get me wrong, I understood all the other stuff (I guess), but this Q wasn't answered - the actual advantage of the rectangle cross section over the round one. The similar round section for the 90 sq mm area is an 11mm diam. rod.

And sorry about being off topic, and about bothering with this Q.

Last edited by isvflorin; 04/11/08 02:08 PM.

Florin
#135025 - 04/11/08 11:16 PM Re: DS12 [Re: isvflorin]  
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Quote
So basically you need to over dimension the cross section... (for) dynamic loads ?
...considering the same cross sectional area what is the advantage of the rectangle cross section...?


A rectangle will generate less aerodynamic and hidrodynamic drag for the same section area.
An eliptic section would be better in order to minimize drag, but it is hard to find, hard to attach to the beam and hard to attach to the dolphin striker. It is also more expensive.

Other reasons to use a rectangle are:
- Price
- Ease to conform to the required shape
- Firmer attachment to dolphin striker extremity.

Anticipating the next question:
A firmer attachment to the dolphin striker increases the degree of hyperestaticity when compared to a a rod or wire passing through a hole or recess in the dolphin striker's extremity, which is the usual setup. This means "stiffness".

Rgrds,


Luiz
#135026 - 04/12/08 01:16 AM Re: DS12 [Re: Luiz]  
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Well, Scarecrow has a very nice setup for his striker, the thing that made me do it another way was the need for welding aluminium, I don't have the equippment for that.
Still when I made the Blade it felt quite strange to drill a BIG hole trough the mainbeam and just put a tube in it.
don't think that that is improving the strenght in any direction...

#135027 - 04/12/08 05:17 AM Re: DS12 [Re: Gato]  
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Quote

Still when I made the Blade it felt quite strange to drill a BIG hole trough the mainbeam and just put a tube in it.
don't think that that is improving the strenght in any direction...



Currently the side walls of your beam are transfering the 1 to 1.5 tons of mast foot pressure from the underside of the beam to the top sit where the mastfoot fitting is. As you beam is rectangular this means the top and bottom planes will be pressed inwards and may develop micro cracks around the fittings.

Whith a large hole in the bottom of the beam the pin can pass straight through and transmit the laods directly to the underside of the mast foot fitting. That is one the advantage of the regular setup that you don't have anymore.

You may well be fine or you may not be with the current setup. Time will tell as I haven't done the math on your setup. Basically, keep an eye on it and if it is fine then you proven this setup to be a viable alternative.

Wouter


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#135028 - 04/12/08 06:18 AM Re: DS12 [Re: Wouter]  
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Here I donít see what you mean. The mast is sitting on a threaded rod going trough the main beam (12mm hole) with a spacer between the upper and the lower walls of the beam. This rod is screwed into a nut welded on the tube going down straight to the strap. So if you want, I can by unscrewing the tube a little lift the mast foot free of the beam by tightening the strap and put no strain on the beam at all. The other edge is maybe RG, I have the feeling that he is going without a striker at all and just using the walls of a bent alu tube.

#135029 - 04/12/08 06:44 AM Re: DS12 [Re: Rolf_Nilsen]  
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That's my experience also. No need to lose the text.

#135030 - 04/12/08 07:06 AM Re: DS12 [Re: MarkMT]  
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I still stress the point, fore those of you building the DS12 stick to the drawings; Scarecrows solution is the best one because he has taken all those things in consideration and Iím sure done the maths on them <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

#135031 - 04/12/08 02:33 PM Re: DS12 [Re: Gato]  
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If you are using a space tube inside the mast then everything will be fine, indeed.

Wouter


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#135032 - 04/12/08 04:58 PM Re: DS12 [Re: Wouter]  

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Good morning everybody (or evening/afternoon depending on where you are). This whole conversation reminds me of the old saying opinions are like a$$holes etc etc.

Time to answer some questions...

1. Do you design for strength or stiffness? 90% of the structure on a boat is actually designed for stiffness, where you are considering allowable deflection and using the Young's modulas to determine what you'll actually get. Checking that a part is "strong" enough if often secondary to the stiffness requirement.

2. Why use flat bar instead of wire. Using wire is fine, however, it requires some more difficult custom parts or the use of expensive tune buckles, neither of which I thought suited this project. The system shown on the drawings is basically the same as what is featured on the paper tiger and it has worked very well for a long time and is easy to build by the home handy man assuming you can find someone to perform 1 aluminium weld. My experiance is that the cost of this weld is usually about 1 case of beer.

Gato's system is even better (although a little heavier) in terms of its ability to be built at home, however, it also requires the use of a welder. With this in mind I'd recommend people make their decision based on what welding technology they have access to. My drawings suggested people buy an off the shelf mast step, however I'll now be recommending Gato's detail.

To be perfectly honest, the other reason I went for the flat bar approach was so the boat would look as much like mum/dads as possible.

#135033 - 04/12/08 11:14 PM Re: DS12 [Re: ]  
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I have to make a small correction here; the system for the mast foot has been around for a while and is not of my own design, I just showed how to do it on a simple way.
For the rest I agree completely.
Iím about to start the making of the mast today, but you will have to wait for pics. Btw the hulls have been car topped for the first time and they were sitting really nice on top of my old Opel.

#135034 - 04/13/08 12:56 AM Re: DS12 [Re: ]  
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Quote
This whole conversation reminds me of the old saying opinions are like a$$holes etc etc.


Some of the non-native English speaking readers may not know that saying...

"Opinions are like a$$holes, everyones got one." Larry Flynt
wikiquote

#135035 - 04/13/08 04:06 AM Re: DS12 [Re: ]  
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Quote

Gato's system is even better (although a little heavier) in terms of its ability to be built at home,



Actually the most simple setup would be how several A-cat (home)builders do it.

They make the receiver for the cone but the cone itself is nothing more then a threaded end. Basically they use a long piece of threaded rod with a tube (=pin) slid over it. They use 4 knots Two under the mainbeam; one to adjust the tension of the strap, the second to secure it. The two nuts above the mainbeam to secure the pin there. The mast foot itself it made from Stainless steel and there are several ways to make the cone receiver but drilling out the head of a large bolt like Gato has done seems to be the easiest. Both holes on top and bottom of mainbeam are now nothing more then 10 - 15 mm dependng on the threaded rod that is used.

Wouter


Wouter Hijink
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#135036 - 04/13/08 04:47 AM Re: DS12 [Re: Wouter]  
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Piiiiiictures please <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

#135037 - 04/13/08 05:30 AM Re: DS12 [Re: Rolf_Nilsen]  
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How about your blog first Rolf. Donít have so much more on the mast foot, but I can put up some pics on the glassing of the hulls.

#135038 - 04/13/08 07:28 AM Re: DS12 [Re: Gato]  
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#135039 - 04/13/08 09:38 AM Re: DS12 [Re: Gato]  
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Thanks Gato. Always interesting to see how others do things. 36gsm is not a lot! I heard that under 100gsm was not really worth the effort, looking forward to hear your opinions after some use. I dont think I have ever seen you use gloves when working with epoxy?? I always lay out the glass on a dry surface, and then add the epoxy on top of the glass. I tried the technique you used in the pics when I started out building stuff but the result was not very good. Mostly my own fault since I did not know about heat and outgassing of the ply, left the boat alone for too long while the epoxy set etc. Perhaps this is more suitable for the builders forum..
My blog.. Just doing the same stuff over and over as we pop out panels, but will update it tonight or tomorrow nigth as I have some new stuff to show.

Now what I really want pictures of is the A-cat striker dolphin structure Wouter describes.

#135040 - 04/13/08 10:35 AM Re: DS12 [Re: Rolf_Nilsen]  
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Just did the sides in that 36g, to have a little resistance against abrasion and prevent the micro fissures you will get in plain epoxy coating, guess we will know soon.
Maybe we could get somebody to do a drawing using textiles (PBO) for the striker.

#135041 - 04/13/08 11:02 AM Re: DS12 [Re: Gato]  
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A PBO striker <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> What did your flat metal striker weight?
If going that route, why not use carbon fibers and lock off the ends with some epoxy?

#135042 - 04/13/08 11:22 AM Re: DS12 [Re: Rolf_Nilsen]  
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Donít know, but the weight problem for the DS12 if there is any will be in the other sense...

#135043 - 04/13/08 05:29 PM Re: DS12 [Re: Rolf_Nilsen]  

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Quote
Thanks Gato. Always interesting to see how others do things. 36gsm is not a lot! I heard that under 100gsm was not really worth the effort, looking forward to hear your opinions after some use.


Rolf, because Gato has used 4mm ply rather than 3mm, the glass is not required as a structural element. so on his boat it is there only as a surface finisher/protector. The standard plans call for 3mm ply with a layer of more structural cloth (Two layers across the bottom).

#135044 - 04/13/08 10:29 PM Re: DS12 [Re: ]  
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I have 300grams in the bottom going all the ways over the chains. As I said before for those of you building STICK TO THE PLANS they are the best I have seen.

#135045 - 04/15/08 06:52 AM Re: DS12 [Re: Rolf_Nilsen]  
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I haven't got pictures of that setup.

Sorry,

Wouter


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#135046 - 04/21/08 11:34 AM Re: DS12 [Re: Wouter]  
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Some small things done on the hulls. Working on the mast and hopefully there will be pics before the end of the week.
http://www.gust.ax/gallery/2008-02-10/08-04-20/

#135047 - 04/24/08 06:30 AM Re: DS12 [Re: Gato]  
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Making of the mast part one...
http://www.gust.ax/gallery/mast/08-04-23/

#135048 - 04/24/08 11:39 PM Re: DS12 [Re: Gato]  
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#135049 - 04/25/08 07:54 AM Re: DS12 [Re: Gato]  
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Opinion?

#135050 - 04/25/08 01:39 PM Re: DS12 [Re: ncik]  
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pfff. stuff
2 questions: do I see correct that both sides are different?
the track [8 figure tube], id that bought ore homebuild as well

I was puzzeld by the last 2 pictures, looks likes bulbs on the wall?

last picture shows very good results

#135051 - 04/25/08 02:02 PM Re: DS12 [Re: Kennethsf]  
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I believe that what you are seeing is the layers added between his laminate and the vacuum bag. He used a peel ply and/or a release film. This absorbs excess resin extruded during the vacuum process along with keeping the mast from bonding to the vacuum bag.



F16 Blade 716
#135052 - 04/25/08 02:10 PM Re: DS12 [Re: bobcat]  

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Both sides of the mast are the same (symmetrical).

Yes Gato built the track (figure eight tube) see his notes in home building forum.

Bobcat is correct on the use of peel ply.

#135053 - 04/25/08 02:16 PM Re: DS12 [Re: ]  

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Note on Building a DS 12.

The carbon mast is an option only. Gato went this route due to a lack of suitable or cost effective aluminium masts in his region. The standard drawings call for an aluminium mast. Any section designed for a two crew, one on trap dinghy or small non trapese cat will have approximately the right bend charcteristics. Long term I hope to have a standard mast available, however, the cost of international shipping means that the rigs will need to be shipped in large batches to make them cost effective. So it will all come down to whether people make this F12 concept a success.

#135054 - 04/28/08 07:51 AM Re: DS12 [Re: ]  
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Sorry for not answering myself, I have been off line for the weekend. Well, once you have used peel ply you donít want to live without it, saves a lot of sanding and all the ďimpuritiesĒ from the epoxy is coming off with it. There is no need to make this figure eight tube, you can as well take down the hale yard in the same tube as the bolt rope.
I decided to have a go for the spar as I have some very bad experiences whit single alu spars shipped from abroad, and just the transport is more expensive than the whole mast homemade. Still the big test for this one will be on the water, so before you start to build letís wait for that one.

#135055 - 05/25/08 11:37 PM Re: DS12 [Re: Gato]  
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Has everybody died?? I'm on my way to bring the sail for the DS12, hope to be sailing before end of week.

#135056 - 05/26/08 02:39 AM Re: DS12 [Re: Gato]  
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Not dead just watching with extreme interest sorry if you feel like your talking to yourself. Your pics will make it easier to build my cats
regards


Jeff Southall
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#135057 - 05/26/08 10:26 AM Re: DS12 [Re: JeffS]  
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Indeed, looking forward to see the "thing" floating.


Florin
#135058 - 05/26/08 02:49 PM Re: DS12 [Re: isvflorin]  
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Not dead at all, just busy on my own end and hoping for some more pictures and information from you.

#135059 - 05/26/08 04:50 PM Re: DS12 [Re: Rolf_Nilsen]  

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Gato,

time for a career change, as it appears you've mastered the role of a thriller author. You've got us all hanging on the edge of our seats waiting to see what happens next.

#135060 - 05/26/08 10:12 PM Re: DS12 [Re: ]  
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There has been things going on, but I have had problems with internet connection, so the blog has been suffering...

#135061 - 05/27/08 07:55 AM Re: DS12 [Re: Gato]  
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On my way out to the island of BršndŲ with the sail for the cat in my car, so hopefully the first try is not so far. It will also soon be time to summarize the building, and it seems that we are well within the goals set for the class. I have spent some 150 hours of work on the boat but that includes making everything at home. Of all the boats I have made this is the one where thanks to Scarecrow it has been possible to build everything at home.
For the costs all included even the beer it stays at 1100 Euros, the things bought to the price accessible to everyone in Finland. I will get back to the final weight of the cat later, itís should be quite on the mark. Hope to find a little bit faster connection to be able to upload pics the next week.

#135062 - 05/29/08 07:38 AM Re: DS12 [Re: Gato]  
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Gato, you mentioned homebuilding most of the parts, does that include rudder stocks ? In case it does...any pics ?


Florin
#135063 - 05/29/08 03:35 PM Re: DS12 [Re: isvflorin]  

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I don't know yet what Gato has built, however, the rudder stocks as designed to be fabricated out of bent box section ali tube as was standard on most A cats until about 8 years ago.

#135064 - 06/02/08 02:16 AM Re: DS12 [Re: ]  
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We are sailing... The first impression is GGREAT FUN. On our way a 100 km raid as soon as the weather is calming down a bit. Pics after that... <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

#135065 - 06/02/08 02:25 AM Re: DS12 [Re: Gato]  

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Wow you're a tease.

#135066 - 06/09/08 05:10 AM Re: DS12 [Re: ]  
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#135067 - 06/09/08 06:56 AM Re: DS12 [Re: Gato]  
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Well done,

Thats a great looking boat, how does it sail?

Gareth

#135068 - 06/09/08 10:50 AM Re: DS12 [Re: grob]  
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Cool color scheme Gato, and the boat really looks larger than 12 feet. Good looking boats, both of them!

On the last picture the trampoline looks a bit saggy? I prefer a tight trampoline, but have not seen a homebuilding option to get it as tight as on a MarstrÝm Tornado.

Looking forward to hearing much more about both boats, the masts, handling, your thoughts etc!

#135069 - 06/09/08 03:42 PM Re: DS12 [Re: Rolf_Nilsen]  

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Very nice Gato,

Can't wait for some windy photos with kids. Sure ages the Pixie Design. Does the Pixie have a new mast?

#135070 - 06/09/08 03:47 PM Re: DS12 [Re: Gato]  
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Nicely done Gato; beautiful scenery as well ; is that the archipelago ?

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#135071 - 06/10/08 01:57 AM Re: DS12 [Re: Wouter]  
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Rolf, the tramp is just a temporary. The Pixie has a ply/carbon mast as the DS12. Wouter, thats deffenetly THE ARCHIPELAGO, puuurrfect for cats...
Will try to get you some windy pics soon...

#135072 - 06/10/08 02:02 AM Re: DS12 [Re: Gato]  
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I still think your idea of doing a camping trip on small (F12) cats (possibly with a fleet of young people/kids) is nothing short of inspired.

I much long to hear your evaluation of paddling these small boats and other abilities like easy launching and beaching.

Wouter


Wouter Hijink
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#135073 - 06/10/08 09:50 PM Re: DS12 [Re: Wouter]  
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The F12 cats are all right for doing camping, even if the Pixie is better, more room to store things. As for paddling it's going surprisingly well, 3 knots without effort using a sea kayak paddel. As for the beaching and launching, well no problems, there is not much weight to carry, you even don't have to emty the stores.

#135074 - 06/11/08 06:46 AM Re: DS12 [Re: Gato]  
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We have been sailing the DS 12 under various conditions, everything from 0 to 25 knots of wind and as far as I can tell the boat is behaving well. It feels completely safe and easy to handle, no surprises there. I have still not managed to get some kids to sail it, so I can still not say how they feel about it.
As for the performance, (crew weight 75kgs) it doesnít need much wind to get it up to 7,5-8,5 knots. The max speed logged with the GPS (no current) around 12 knots with only the main sail. We made a raid of 60 nautical miles with the ďnice ladyĒ on a Pixie 14 and it was a close race the Pixie a little bit faster (only main up).
It would be fun to have a V-shaped "old fassion" F12 made, as the F12 is underpowered I think it could put up a good race...

Last edited by Gato; 06/11/08 06:51 AM.
#135075 - 06/11/08 06:47 AM Re: DS12 [Re: Gato]  
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Quote

The F12 cats are all right for doing camping, even if the Pixie is better, more room to store things.


Is the Pixie noticeably wider then the F12 ?

If the F12 design c.q. specs is to be adjusted for such trips what would you change ?

Hull length platform width or trampoline size ? Etc ?

Wouter


Wouter Hijink
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#135076 - 06/11/08 06:50 AM Re: DS12 [Re: Gato]  
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What are the basic specs of the DS12 ?

Mast length
Sail area
ready to sail weight
Overall width
Overall length
etc.

We can learn alot from this experience gained with the DS12 and possibly optizime the F12 concept a little further.

Many thanks in advance !

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
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#135077 - 06/11/08 06:54 AM Re: DS12 [Re: Wouter]  
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The Pixie is 220 wide, and that does make a difference putting up a tent, still the 2 meters is enough for the stability of the platform.
I would maybe add a small kite to benefit a little bit more going downwind.

Last edited by Gato; 06/11/08 06:59 AM.
#135078 - 06/24/08 01:25 PM Re: DS12 [Re: Wouter]  
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The first kid in the world on the DS12! Crew weight 40kg, wind speed 15 knots.

Attached Files
149255-P6240037.JPG (899 downloads)
#135079 - 06/24/08 01:26 PM Re: DS12 [Re: Gato]  
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Even more fun

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149256-P6240038.JPG (825 downloads)
#135080 - 06/24/08 01:29 PM Re: DS12 [Re: Gato]  
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In short, they just love it <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

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#135081 - 06/24/08 02:09 PM Re: DS12 [Re: Gato]  
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Quote
The first kid in the world on the DS12! Crew weight 40kg, wind speed 15 knots.


Please, tell us more!
What about the boat speed? Was he faster than the Lasers visible in the background? Did he feel the boat overpowered or that a trapeze would be necessary? Any opinions?
Also, tell us about the kid: his age, previous multihull and dinghy experience, comments...


Luiz
#135082 - 06/24/08 04:50 PM Re: DS12 [Re: Luiz]  

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Gato, you bring a tear to my eye every time you post.

Trapese? he's not even hiking.

#135083 - 06/24/08 05:43 PM Re: DS12 [Re: ]  
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Well done, great hull shape, chines are good.

Darryn
Mozzie
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#135084 - 06/25/08 12:23 AM Re: DS12 *DELETED* [Re: ]  
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Jeff Southall
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#135085 - 06/25/08 12:33 AM Re: DS12 [Re: JeffS]  

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Jeff,

I've just sent an email to the guy who does the metal work and will let you know when I do.

#135086 - 06/25/08 12:51 AM Re: DS12 [Re: ]  
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thanks for the photos Gato
I cant wait to build my boat
I am never going to sail my 420 again
Scarecrow when will my 008 kit be ready
my colours will be heaps better then Gatos
and I am going to call it watch out coming through
regards Maeve Southall


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#135087 - 06/25/08 01:06 AM Re: DS12 [Re: ]  
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Scarecrow, Now you and I know real pressure thanks to Gato
regards


Jeff Southall
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#135088 - 06/25/08 06:56 AM Re: DS12 [Re: Luiz]  
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It's faster than the Laser in windspeeds over 5 knots, downwind it can sail around it.
Trapeze <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" /> the kid asked for a kite when he came ashore <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
In fact I think we are quite all right with the sail area and the mast lenght. At least here it's not allowed to have somethig on the car that exeedes it with more than 2 meters.
This kid has been sailing Optimist, and since last year he is crewing on a 29:er, no multihull experiense, it took him about 10 minutes to get the hang on the thing. this cat is extremly easy to handle.
At least here where the cats are not so common I think it could last up to 15 -16 years old equipped with a kite for the older ones.
http://www.gust.ax/gallery/f12/08-06-25/

Last edited by Gato; 06/25/08 07:04 AM.
#135089 - 06/25/08 12:24 PM Re: DS12 [Re: Gato]  
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Gato, you are from now on one of my heros! Please dont disappear from us. This is the coolest little thing I have seen in a long time, and you did it all from scratch. Great stuff, hope some kids get interested enough to take up catamaran sailing. What happens if they come at you asking for boats?

#135090 - 06/26/08 01:11 AM Re: DS12 [Re: Rolf_Nilsen]  
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Not thinking of disappering quite yet, even if I sometimes are a little bit surprised about the catsailors. Went to see the guys on the Archipelago raid, and there was only one that even bothered to answer some questions...
If they come to ask for a boat, well I tell them to build one...
I am alredy looking at something like this http://www.graingerdesigns.com.au/stock-plan-detail-145.php

#135091 - 06/26/08 07:20 AM Re: DS12 [Re: Gato]  
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Grainger designs are pretty good......good choice.


Marcus Towell

Formula Catamarans Aust Pty Ltd
#135092 - 08/06/08 06:28 AM Re: DS12 [Re: Marcus F16]  
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I got to sail Gato's DS12 last week and I think that I should post some comments about it (from 75 kg's adults point of view).

I was really surprised how well it handled my weight, conditions were really light and I was significantly faster than a small (<50 kg?) girl in Laser 4.7 directly downwind. Biggest problem in light conditions was that it took some speed to get the daggerboards work and it meant few seconds drifting sideways every time that gust came (when I wasn't moving at all), after I gained some speed pointing abilities were decent. Also the boat was really light to handle on the ground, I guess that even mom with ~12 year old kid could manage with it.

If mass production prices will be low enough and it doesn't gain lot more weight then I believe that F12 has lot of potential to be a success.

ps. Test sail got me wondering about foam-carbon (a la A-cat) DS12 weighting about 40 kg's (for adults only, the XXX edition <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />).


Valtteri Blade F16
#135093 - 08/06/08 07:24 AM Re: DS12 [Re: valtteri]  
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It's a funny toy, Valtteris idea is that it's easier to get the kilos of from the boat than from ourselves... <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

#135094 - 08/06/08 01:58 PM Re: DS12 [Re: Gato]  
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Have any more kids/youths sailed the boat? If so, what did they think about the experience and the boat?

The "going sideways" in gusts sounds like a loose nut on the tiller <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> (Sounds like you were oversheeted, sheet out, sheet in ?)

#135095 - 08/06/08 03:33 PM Re: DS12 [Re: valtteri]  
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Great report Val !

I'm really pleased to see the DS12 (F12's) living up to the expectations.

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#135096 - 08/07/08 06:02 AM Re: DS12 [Re: Rolf_Nilsen]  
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There are kids sailing whenever there is a possibility, and I hope even more after the summer holydays are over. The respons is good, but it's the parents who have the money...
What I'm doing for the moment is being present to let the people notice the toy, and it's drawing attention.

#172913 - 03/26/09 07:44 AM Re: DS12 [Re: Gato]  
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Great thread guys. I'm a Math teacher here in Texas. I built 3 wooden boats with my students in a Math class a few years ago. If I may make a few suggestions I think it may make it actually a bit easier.

Scarfing is a process which can give students a bit of trouble. The reason being that if you don't scarf evenly you'll end up with voids in the hull or dimples. A simple butt block joint works well and is VERY easy to make for the students. You can use it as a structural point as well and put braces on each side. Second, have you thought about stich and glue for the construction. I know we only built 12 row boats, but Epoxy and Meranti 6566 wood still only turned out to be $300 per boat using this method and the only real tools needed were a jigsaw and sandpaper.

You can see some pictures by going to my website www.texasspearfishing.com and looking at boat building 101

Last edited by Rcwade; 03/26/09 07:45 AM.
#233952 - 06/22/11 06:45 PM Re: DS12 [Re: Rcwade]  
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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

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