Catamaran Plans

[Bill Baillie]

Does anyone know where I could get a good set of plans for a racing catamaran in
the 16 to 18 foot range? I was thinking of building it in cedar strip as I have some
with this construction method and I like the look of well done cedar strip.

[Wiley Baggins]

Not 16'-18', and not a stripper, but our hosts have plans for a 14' cat. I doubt that you would go far wrong adding a couple of feet in length, and if you wanted to work a bit harder and strip plank one, well, you probably would not get yourself into too much trouble there either.

http://www.woodenboatstore.com/store/images/400083.JPG

PIXIE, plans available at the WoodenBoat Store.

[Tom Lathrop]

Two one design racing catamarans come to mind. The one that fits your length is the A Class which can be found at:

http://www.usaca.info/

Another that is most popular down under that is 14 feet is:

http://www.papertigercatamaran.org/

Both are all out racing machines for single handing and are cat rigged.

Another that is longer at 20 feet and is fully rigged with jib and spinnaker and was designed for the Worrel 1000 race is at:

http://www.bandbyachtdesigns.com/worrell.htm

This is a high performance boat for two crew but has no class association.

[A. Mason]

Please educate me. I can understand referring to "Pixie" as a "Cat" [short for catamaran] but reading the description in WB Plans book II, where the sail plan is referred to as a "standard sloop rig," I have a definite problem understanding what they mean.

Visually looking at the line drawing profile of the inwater profile sail plan, I would be far more apt to call it a "Junk" mainsail. The angles of the edges of the maainsail and the apparent through battens visually says "Junk."

I'm not referring another term for "garbage" or "trash" but to a long recognized and highly respected sail shape.

I am sincerely curious as to why it is referred to as a sloop. BTW, I preferred sailing on a "cat" than in a "Rhodes 18" in my younger days - I felt safer and less apt to have to swim to shore.

Thank you, Anita

[Tom Lathrop]

Sorry Anita, your question is confusing. The Pixie sailplan is clearly just a Marconi sloop with fully battened main. Nothing about it says junk rig.

[Todd Bradshaw]

As Buddy Ebson once said: "Everybody knows that there are three types of boats - a Cat (catamaran), a Half-Cat (monohull) and a Cat-and-a-Half (trimaran)".

The catamaran mainsail has a lot of roach - that curving, extra sail area aft of a straight line drawn between the aft end of the boom and the tip of the mast. To make this area productive (rather than just flapping in the breeze) long battens are used to support it. Most of these boats (as well as iceboats, racing sailboats and other quick-accelerating hulls) have gone to full width battens. They make a more rigid, more shape-controlled airfoil, especially on a boat that may experience fairly drastic boatspeed changes in short periods of time.

Where the first reaction of many monohulls to a puff is to heel over more and then gradually speed-up and "catch-up" with the new wind velocity, light, easily-driven hulls like catamarans, trimarans and high performance monohulls may heel a bit as well, but the feeling you get is much more like the boat is squirting forward. These light hulls will also quickly decelerate when the puff is over or when sailed into a lull. Without going deeply into the fine points of sailshape theory, it's been shown that the full-battened, more rigid sail handles these changes better than the traditional type with shorter battens and less rigidity.

The Junk rig and sails are different. The sails are actually a variation of balanced lugsails (4-sided having the leading edge out in front of the mast with a yard up top and a boom on the bottom). Unlike most Western-style balanced lugs, junk sails are divided into several sections by a series of stiff, full width battens which keep the sail flat (they're also cut flat - no draft, etc.) The visual confusion is that again, unlike most Western lugsails, the Chinese versions have a big curving roach that looks similar to the one on the beach catamaran. Instead of having a mainsheet hanging off of the boom, junk rigs have a bridle with smaller strings going up to the aft ends of each batten. The "boom" may also just be a heavy batten and all those strings allow precise control over sail twist at various altitudes above the deck. How can a flat sail work? I dunno, but the only bad things that I can find written about them are that they don't point very well in light air and the heavy battens give you a lot of weight aloft.

The "Junk Rig" has a lot of variations, but they share some basic features. The masts (some have one, some may have several) are unstayed. No wires interfere with the sail trimming and the whole mast is free to bend in the wind, like a pine tree to a certain extent, to dissipate puffs. As far as I know, the Chinese never invented the jibsail (which is good, since with no wires, they also failed to invent the jibstay to hang it on). Instead, they just used a smaller mast and another lugsil sail forward and often a third aft as a mizzen.

So yes, there is a visual similarity between the typical full-battened catamaran mainsail and the Chinese lugsail used on a Junk, but in reality, that's about all the two have in common.

[ 08-17-2002, 02:37 PM: Message edited by: Todd Bradshaw ]

[A. Mason]

Thank you Todd! I appreciate your detailed answer to my question. - Anita

[chrisk]

Wooden Boat also has plans for the 16' Quattro Catamaran, study plans can be found in "40 Wooden Boats", which is a 16' beach cat. The comments call it "striking to look at and exciting to sail". I don't know if it meets any racing class specs and it's a stitch and glue design like the Pixie. The design ultimately comes from the same designers as the Pixie. You can check out to see if they may have some design that meets a particular racing spec at Wood Designs (http://www.sailingcatamarans.com)

[flyon]

Todd, Actualy it was Rudy Choi who said that I believe he designed Poly Con ( for the trans pac race) for Buddy Along with a lot of the first beach cats in the sixties. Glen L has a couple of good cats in there catalog

Fred

[bainbridgeisland]

Try Kurt Hughes, a multihull designer in Seattle. He has some great boats, some of which may do the job. Go to www.multihulldesigns.com (http://www.multihulldesigns.com)

[ 08-19-2002, 11:08 PM: Message edited by: bainbridgeisland ]

[Tomcat]

I don't think Kurt has any beach cats.

The perfect plan would be the Gougeon A cat which is developed ply, and very nice. They stopped selling plans, but might have some stock. Anyway the A-class is a class, so there must be info on the web, one would think. You might ask around to see I anyone has these plans built or unbuilt.

I would also request the series of Gougeon Epoxyworks back issues (free) in which JR Watson custom upgraded a hobbie with new hull shapes etc, right up to designing a hovercraft trailer for it. Too wild.

A large alternative would be the 20' Tornado, which is an Olympic one design which would help on a lot of fronts like sails, and resale.

Chris White has a few bizare cats with lift generating planing rigs that go like h***.

[Jim Mathieson]

JWD James Wharram Designs has a Hitia 17 Cat with a Soft Wing Sail that is excellent.You can even camp in a two man tent on it.See
http://www.wharram.com/ctrek_photos/ctrek_image11.shtml
JIM

[ 08-20-2002, 02:34 PM: Message edited by: Jim Mathieson ]

[Figment]

the A-class of cats is a very rapidly growing class. i think the A class worlds had 70-something boats last year.

IMHO, it's too much of a techno-development class. you need a nice thick wallet to stay competitive. This may change, however, with the development of the new F18HT (Formula 18 High-Tech) class which may draw the big-spenders away from the A class.

If you haven't been already, go to www.catsailor.com (http://www.catsailor.com) for a whoooooole lotta info.

[paladin]

I don't think Wharram designs Cats...he does double canoes.........

[Bill Baillie]

Thank you very much for all your informative replys.

To Tomcat: your point about sails and resale value is well made. I have built both strip and stich and glue hulls before and the strippers sold much faster and at a higher price than the plywood.

I will certainly check out all the suggested sites.

Thanks again!