CSC 30 Catamaran- the coastal passage

And as Chris White once remarked to me:

"It takes the same amount of time and money to build a crappy boat. Might as well build a good one."

Goes along with Richard's post which I also say I have to agree with.

 

Roger also mentioned he had a builder in Africa building a cat and the ply he was using for beams was probably worse than what we use for packing crates in Australia, hence the over engineering as he could not control what builders used even when specifying premium product.
Unfortunately if it all turned to **** , the public and the blogosphere tend to put blame on the designer and rarely mention the builders crappy choice of material.

Plywood is amazingly strong, if you can keep it in column.
I have a mate with a 11m Chamberlain designed cat, mast/main BH is a single 12mm ply arrangement from memory (it may even be 9mm) with windows cut through it, but all kept in column with ring frames and furniture.

 

And Chamberlain is one of our great designers, a quiet achiever, certainly up their with Crowther in quality, the Cirrostratus trimaran is a legend IMHO along with the Parralax catamarans.
RR

 

I don't doubt that plywood is amazingly strong.

I have plans for a cat with plywood beams and they sure don't go together anything like the ones in this picture.

What am I missing?

The "height" of a beam (from deck to terminus) is usually on the order of several feet tall, in my experience. Why are these beams looking to be about 6 inches to a foot (150mm to 300mm)?

Is there something else aside from those tiny little "beams" that are bolted to the bulkheads at the top? How are those kept in column? The bridgedeck?

FWIW: I am accustomed to beams that are either glass/foam and made up of multiple faces, creating a box (these in the picture are just a single span - no box), or... plywood beams consisting of a truss type architecture inside them.

Picture one of those beams under a twisting motion. Yikes! They would surely give since they don't have good support from bulkheads and aren't "tall" enough to provide much resistance to bending.

I just can't imagine the other boats I'm thinking of (many modern and older catamarans) have been built incorrectly. I'd have to guess this catamaran in the pictures was built incorrectly (in terms of beams).

I'm not claiming to know anything about design. I have just seen a lot of beams and these are the narrowest, flattest (no box) ones I've ever seen in my life.

 

Ok, ive just perused those pictures and i cant tell if they are box beams or just a 2x6, if they are indeed box beams they are plenty big enough,that boat is essentially a net and tube boat with a cabin hung from the beams. I owned a Mac 36 cat which was 36ft x 18ft which was held together by 3 @ 6.625" dia aluminum tubes set into troughs which were glassed to 1/4" plywood bulkheads, not good marine plywood mind you, but american plywood. The mast beam and aft beam were 1/4" wall while the fwd beam was 1/8" wall, it was a more than adequate structure. Now if that is just a 2x6 or 2x8 bolted to the bulkhead then .....
Steve.

 

Looking at the Photos blown up a bit the beams look like laminations of ply so a fair bit of grain along the length, they would be held in column by the deck tray so. . . . . . hmmmm.

 

Despite all that I actually think it is a sweet looking boat for coastal use

 

Definately box beams, according to the plans anyway dimension wise they are similar to the beams on a Woods Gypsy (which is definately a better boat imo) but as I said earlier connections to hull/bulkhead could be improved imo. But as a simple coastal cruiser I think it would do an admirable job, who needs all the crap some people take cruising, this guys got his simple boat and he's out there doing it, instead of talking about it like most of us!

 

Absolutely, power to him !

 

The article says hes been building them for years for customers, any idea how many are sailing?
Steve.

 

I liked how simple the hulls went together. If he resolved the beam and materials issues I think he'd be onto something. Whole thing looks modular which is another plus.

Hey Richard, you should do more power cats. I liked the little one you did. I'd just think that one say in the same 30's range as this guys might end up a good seller.

I've played around with some sketches of a 35' with an almost commuter looking cabin arraignment on it.

The hulls simplicity is really a plus. But I'd be curious about how dependable a scarf in a single layer of thick ply is as apposed to several smaller scarfs in multiple layers of thinner material, offset of course.

oh and I'm seeing what looks like CDX grade on the bulk heads and ABX on the sheathing.

 

I have completed the plans for the Skoota 20 and 24 power cats, both are now selling well

I am currently working on the designs for a 26ft (stretchable to 28) transportable cruiser and a 36fter

More on my website as my ideas progress

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

The plywood in the photos does not look any worse than most US made plywood sold as marine, in fact many of the earlier Searunners were built of ply that looks no better than that, its hard to make a judgement based on those few photos. There would be nothing to stop you from spending more and using better ply. Richard,any eta on the 36ft powercat design, i kinda liked the 34 you had on your site for the last year or so,the narrow beam,light weight,great fuel economy are very appealing.
Steve.

 

the stuff he used for bulkheads looks exactly like CDX which is an exterior grade used in roofing and for shear panels. Its the cheapest of the actual plywoods, or at least it is around here. Given there's only four, two to a side, it seems kinda silly to use such a cheap material in such a critical position.

I'm sure it will last a little while at least, but I'd be funny on trusting my life to it. Whats worse is OSB, I've done my share of insurance repairs and that stuff fails all the time.

 

I agree, it looks like an Aus equivilent to CDX in the bulkheads, but the hull panels look as good(or as bad) as any American "marine plywood" ive seen, you just cant tell from the pics. Funny sidebar, about 30 years ago i went with a friend to look at a Ferro Hartley South Seas that a friend of his dad was building,he had done a nice job of the hull but was building the cabin structure out of particle board, eventually it went in the water and of course the house didnt last long, it sat on the hard at the marina for years until the engine was pulled,the house removed and then the perfectly good hull was towed out and sunk as an artificial reef for diving on, im sure its still there perfectly sound.
Steve.