9m Steel Catamaran; thoughts?

I have just got the plans for the Boden 9m steel Cat from Australia, well drawn and easy to understand, very impressed . but the designer has used a lot of different sizes of plate and sections...yikes.

I was hoping to substitute angle iron for the recommended folded plate for framing the hulls, I'll have to ask the NA. Makes sense for the cross beams to reduce the possibility of cracks forming in the hot formed angle iron sections.

I've removed dimensions to preserve copyright Boden boat plans. http://www.bodenboatplans.com/product_info.php?cPath=1&products_id=23

 

So $200k for a basic hull?

Bloody hell...I am astounded by these prices.

I realize the time/work/supplies involved and different uses etc.
BUT for a bit over twice this price I bought a 13 year old 68' luxury motoryacht (that looks just like the ones built in 2012) in near perfect shape,900 hours,RIB,fully serviced,fully supplied, full tanks,new bottom,etc.

What would the cost be-including your time spent in not earning income- to have the interior and systems done to a nice spec?


There are any number of good,used powerboats out there,maybe 12 to 15 years old from 40 to 45' with low hours and very well cared for-and needing nothing-that can be had for $150-200k,as opposed to just getting a bare hull that's only 30' for the same money.

 

I totally agree with you; but have a look at second hand catamarans to compare like with like.

Outrageously priced for their age and size ...!

 

Rusty..you were talking about a Devlin, AFAIK he doesn't do cats.

But it's the same thing with cars. My 12 year old Bentley costs the same as a V6 Camry.

I looked on Yachtworld and the only power cats under 30" are fishing boats with little living space or pushing $200k.
This was the only reasonable one I could find:

http://www.yachtworld.com/boats/200...6/Costa-Blanca,-Medit.-Sea/Spain#.V0ZCargrKM8

 

boden boats are good . i have seen a pic of 1 of these cats setup as a pro fishing boat with twin 4236 perkins.

 

I was just quoting Devlin as an example of the enormous number of hours it takes to produce a good quality faired plywood hull , which of course is reflected in the price. I seem to rember that he built the most expensive ply boat ever built for a client for far in excess of $1m .

Thanks for that link to the MC30; that is very reasonably priced Cat, but a truely horrid looking design. Lol. It would make a fantastic base boat to cut up and re- model into something nicer.....but then again you could invest that money with a little bit more into something like the BW Seacat hull or similar . It had actually occurred to me that cutting up a motor sailor Cat might make sense , if purchased cheap enough . I was actually on a Catalac 30 last week and the owner had bought it for just £7k with burnt out engines and no interior. I believe the Catalac is notorious for hobby- horsing down wind, and slamming in any sea over 2'......so maybe not such a good idea after all.

 

Ive had a look on Google an could'nt locate any that had been built and launched. Do you know its approx location in Oz?
The Boden design is actually designed for twin 400kg diesels, but one of the newer yanmar 110hp type would only weigh 250kg each so considerable savings could be made.

Nz and Australia are the both renowned for Cat design; the very best in the world bar none.


Are you interested in building the Boden design? I'm going to go ahead and try to find somewhere to start the build. Although the frames look complex, they should go together reasonably quick . OK, so there's no plating info, but I much prefer to cut cardboard templates to ' offer up' the plating to the frames to get an exact fit rather than loft the shape, or indeed get it plasma cut only to find its 1/2" too small. What's not to like; cheap materials, easy and quick to tack assemble , fast to weld 3mm plating..... And can be built outside and constructed in any weather .

 

it was years ago in a boat plan magazine i used to get but i don't have it any more. i remember the cat was built for line fishing in queensland but there must be others too. i don't plan on building anything myself, quite happy fixing old boats at the moment. i hope you post pics as you build.

 

We built a steel power catamaran (39' x 16') here 15 years ago - the main reason for using steel (rather than aluminium) was the initial cost of construction. When the Owner found that the same boat in aluminium would be almost twice the cost (for the metalwork alone) he decided to go with steel.
However on reflection afterwards I wouldn't do this again - ok, the initial cost of the steel boat was less, but I subsequently spent a small fortune (I vaguely seem to remember about US$ 7k - and this was 15 years ago) of the Owner's money on paint just for the initial outfitting, never mind labour for applying it, and additional paint for touch up work later.

The boat was built as a floating rum shop, and for the first couple of years of operation she fulfilled this job very well. I have attached some photos below of her.
The first shows her leaving the Builders yard, about to travel to the haul-out yard for completion of outfitting.
The second photo shows her not long before she was launched, while the 3rd and 4th photos show her in operation as a floating rum shop - she would usually have a stern anchor out, with 2 bow anchors on the beach, and the ramp made for for easy beach access.

The final photo of Rumpy Pumpy (yes, that was her name) shows her in her final reincarnation recently - over the years she has had pointed bows added, extra top deck added, and (just recently) a huge bimini canopy over the top deck. The latest owner found out the hard way that you cannot just keep adding weight to a boat without taking into consideration your reserve buoyancy.

If I was to build a metal boat again, I would definitely go for aluminium - especially as we had also just built a 49' x 16' aluminium cat for coastal cruising before we started on the floating rum shop.
And 15 years on she is still working well - she has needed minimal maintenance over the years, just the usual bottom paint, anodes, touching up deck paint occasionally...... the extra investment by her owner at the beginning was well worthwhile. I'll attach a photo of her as well.

 

Thanks for posting the photos and all the interesting info.

I agree with your conclusion about steel cats, but from a home building point of view welding alloy is a professionals job that no amateur could successfully undertake, which along with the high cost of alloy would skyrocket the project out of reach.

What a beautiful location! have you got any room in your yard for a self build? Lol.

 

Apologies, but I was only the original designer of these two cats (I had nothing to do with the subsequent modifications on Rumpy Pumpy!) - here is a link to the Company that did all the metal fabrication work on these two vessels.

http://www.ssl.bb/metal-products-division/

Even 15 years ago they had a state of the art CAD / CAM facility, and all of the plates were cut on their plasma cutter, which was amazingly accurate.

These were among the first boats that they built, and they much enjoyed the change from building steel frameworks for buildings and garden gates.

And it was very quick - the 49' ally cat took 3 months in total from the day when the first plate of aluminium was cut, to launch day.

 

Aha, I didn't realise you were the designer; a very unusual speciality designing steel Cats!

Just wondering what sort of size plating did you choose on the hulls, and were the frames fabricated or cut out with the plasma from flat plate ? I would be interested in your opinion on the differences between folded flange plate vs. Angle iron?

Do you like the Boden design?

 

Rusty you might be slightly overestimating the difficulties of welding aluminium alloy. It is certainly more difficult to weld properly than steel but the equipment is similar; it needs to be a bit more powerful thickness for thickness compared to steel and I'm guessing that the material thickness of the boat will increase for the change to ally. Instead of being a dab hand in a few days it might take say double the time to become proficient at the more basic type of joint. No disrespect to ally welders but they're skilled and practiced artisans not supermen. One of the problems with ally welding is that its easy to get a terrific looking weld that's just not any good because the weld lacks penetration and is almost sitting on the joint. You really should go to a local engineering shop and natter to the welders, see what they say. What Bajan said about the cost of the protective system is an eye opener. I didn't expect it to be cheap, of course.

 

I paint my steel boat with international industrial 2 pack epoxy, its only available in large 20 ltrs cans. Seems to stick well, but it's not the sort of finish you would find on a super yacht, but maybe on the Tug pushing it into its berth. Lol.

My version of the Boden Cat will be more workboat/tug than cabin cruiser.

Re alloy welding, it seems to be heat control that's the skill; too much and the joint becomes brittle, too little and as you say not enough Penetration. There's a thread here on this forum about the art of alloy welding.

 

So whats your ball park estimate of the paints costs> I haven't got a clue The stuff you use may not have the best finish, but protection wise its got to be top notch to look after the 3mm plate.