Bridgedeck centreboard why don't they work???

Thanks for claifying that Pogo.

 

...from another forum discussion, Asymmetric Cat Hulls

With the Prindle hulls you will notice a more pronounced 'toe-in' of the keel lines. ( I termed it 'biting their way to weather')

 

Very interesting posting !!
Sure would be nice to see some photos, etc ??

 

I never realized this,...or I forgot all about it !!

 

Dart 18 cat

Look at this website I just found while looking for a close-up view of a Dart's hull,...very interesting material and history

http://sailingtrivia.ravenyachts.fr/2013/08/the-evolution-of-sailing-multihulls.html



..at the very bottom of the page, the Dart

 

thanks, this is the good information. Now does it scale, say to 10m?
Immediate reaction: just from lines it looks like it would hobby horse just about everywhere.
Max buoyancy at a station, pronounced rocker, fine fwd entry.
If you load it down so the WL is far above forefoot, wouldn't tacking be difficult/impossible?
We need Ilan Voyager's help in finding his friend's cat. 14m at 3800 kg. You are probably the closest to the last known position of Mekong/Cambodia.
edit: Must be getting old, looked at those photos hard and still can't see how the hulls resist lee drift, anywhere.

 

Please read the posts more carefully. There are not clips. Stop jumping from one post to another.!!!! And visibly you do not understand what it's written.

He retired in 1990. He died in 1997 too young, f***** cancer. No web.
I wrote that the boat was made in my shipyard. So you can assume I made it.
About the light weight. That ¡s for your education; do not compare 2 very different boats. The lone common feature they have is to be catamarans.
Imagine now a boat for the tropics 12m like a 1988 F40 with already slim low freeboard hulls (1 m at the LWL), just add 2 meters in the central portion. Very moderate width.
Spartan accommodations for 2 with only 1.50m head in the hulls, not luxury for 6. Just 2 light outboards 100 kg each and a 2kw genset (25 kg) not hybrid diesel engines.
2 short masts with only a 35m2 mainsail per mast. A very low center of sail, so the stresses on the rigging and the hardware are very moderate. The compression by the masts on the beams is ridiculously low. A 95m2 mainsail on a 18m mast is another thing...
The efforts on the hull induced by the Dart keel are nothing compared to a beefy deep daggerboard. Furthermore the dart keels act as protectors of the bottom of the hull. So no need there of a thick lamination against the abrasion and punctures in a dry mooring. The dart keels add a lot of vertical mechanical inertia to the hulls, so you can go lighter in the scantlings. It's a virtuous circle.
The cata of my friend was a very small boat compared to a SIG 45, and the price was surely 5 times lower. A used SIG 45 is in sale after just one year (very bad sign) at 845000 Euros...ouch!
Remark.3 The SIG is 5.5 tons LIGHT. That means you have to add a lot of things.
For your education; wood composite does not need autoclaves...You are not going to heat at 85 or 100 C a plywood, that would be a very bad idea.
No CNC. Plans by hand, calculations made with a cubecalc sheet on DR Dos OS and a ruler, plus a HP scientific.
In 1988/89 nobody serious in engineering used a Microsoft windows 1 or 2 with the horrible Dos plagued by memory problems resulting in the blue screen of death, that was a total junk.
For the light jobs DR Dos, for the serious stuff Unix, or mainframe. All by line commands on a terminal...

 

I don't detect pronounced rocker. As far scaling it up it would have a very fine slenderness ratio. I've only sailed on one twice in my life, and it certainly did not exhibit the hobby horsing that a Hobie cat exhibited.

I also liked very much the boomless feature.

BTW you do realize that tacking a multihull (big or small) is a little different that monohulls. You are best advised to sail the multihull in an arc to complete the tack,...sail it thru the turn. DO NOT throw the rudders over quickly expecting the boat to 'pivot' around'. Sure having bows just kissing the water can be helpful, but they are not necessary in all instances.

If its over in this area I could make a real effort to go find it, as I am up in the northern part of Thailand right now for the next 3 weeks.

I don't quite understand the hydrodynamics of it myself, but as Pogo pointed out earlier there are 'body shapes' that can accomplish what some of our foils/wings can do.

 

had I known it was so long ago I would not have asked for a web site.
Sorry to hear about his untimely death.
Thanks for the info on the boat. He sailed it all over Indo-China? At that time very few sailing aids so a very impressive feat. His boat is still sailing - what was its name?

 

I am very sorry to hear that he passed away too early.

Do you still have an association with a boatyard that builds in wood composite?

I am very much a fan of epoxy/wood composite constructions. I have several friends with boats constructed thusly,..one a 62' powercat (the first one on this page http://www.trawlerforum.com/forums/s3/powercat-trawlers-11299.html

More recently another old associate has suggested I consider a wood/epoxy
hull for a redesign Pilgrim canal boat project, rather than the steel hull I was considering.
More over here, Wood Hull & Deck on a 40' Pilgrim Canal/Trawler

And btw they utilized some computer cutting technologies even on his wood vessel

 

Brian. I have no pics. In 1996 a fire destroyed my house and my office, with the library, books and mags, all the pics albums, my archives and all the personal stuff, plus the 2 computers. When I say all was destroyed, I mean that all I had were the clothes on my body, my shoes, my wallet and the car. It remained nothing, except my memories.

Happily my wife and children were visiting their mother and grand mother, 600 km from there. They had to stay for a long time...Happily also the old dog and the cats were outside, alive and well, just very scared.

Many thanks for the Dart pics and drawings. I did not remember that the hulls were so in V, The Loday's dart keels are very different.
On the cata of my friend there were true apexes, more like a skeg, with thinner sections. When I built the boat, I made the bottoms of the hulls in strip plank and added and faired the apexes, that was the only way to make them. The leading edges were very thin, a 5 mm titanium rod was added after routing the fiberglass edge , glued, screwed and faired to respect the radius of the edge. The trailing edge a 2 mm plate was embedded in the fiberglass.
My friend insisted heavily that the complex profile should be respected within the millimeter and controlled several times the work. That means for me that he calculated carefully the shapes and wanted to have it working as intended.

 

WOW, sorry to hear that about your fire, etc. Just the other day one of my primary laptops decided to give it up (a hard drive problem of some sort). I was looking thru some videos on line and may attempt to get that hard drive back into action, or at least extract some of the old data once I get back to USA.

Lucky I had a backup laptop I could put into action (one I had originally given to my wife). My Thai stepson says I should replace that other hard drive with a new solid state one. I think I may give that a try as well, even thought I am a handicapped computer guy

 

Thats funny. I'm not sure why we are comparing H16 and Prindle 16 hull shapes . INFERIOR?? really.

Geof Prindle had Hobies work to build on yet performance was similar. Infact the VYC yardstick for the Prindle 16 is 2 points slower than the Hobie 16.

 

Brian I have no idea about the cata.
My friend came back in urgency by plane, and died of leukemia less than a month later at the hospital. His wife died within the following year. No children.
The boat was left somewhere in the Philippines, and I do not know if someone did eventually something. I'm afraid that the boat was abandoned, then pillaged, stolen or destroyed. That happens relatively often in remote parts of Philippines and Indonesia, where yachts have no value except that can be pillaged, and the authorities are the first at the pillage.

 

+ that suggestion. Put a 250 gig SSD into my iMac -- like a new machine.
But now 500 gig SSD is cheaper.
Use a backup program to copy everything to your old HD.