9m Steel Catamaran; thoughts?

I think Lotus cars in the UK are constructed with a bonded alloy chassis. My son was looking at CCM motorcycles which use the same bonding techniques.

I believe special super clean laboratory conditions are needed to get a reliable joint ?

 

i think he means stainless steel. why do you think ply is slow.

 

epoxy does not need lab conditions, you just use it according to conditions specified in the data for that product, ie:correct hardener for your climate conditions.

 

Lol!

I have only scratch built a tiny ply epoxy sailing dinghy, and rebuilt a Mirror stich and glue plywood boat.

I've been following a 30' ply build on the trawler forum, and its progressing at snails pace ...

Bubbles forming under the newly wetted & layed up matting, requiring cutting out and repairing.

The massive task of sanding down between layers.

The rough finish that needs fairing and fillers.

The expense of epoxy, and the limitation on cold or damp weather curing.

..I'm not conversant with modern lay up techniques; are any of these problems resolved?

 

The problem with bonding the hull plating could be the butt jointed chines. You would have to design these with a large overlap to get a big glue surface area which would require folding the plate on a press; very time consuming and difficult to get the correct angle of overlap on curved surfaces .

I could imagine salt water getting into the joints corroding and destroying the integrity of the glue bond.

Maybe unfounded fears?

 

true i wondered about the overlaps and how they do it, unless its done with fillets as in stitch and glue. i don't think corrosion in the joints is an issue unless they are a bit dry. but plenty of epoxy squeezing out when clamped will prevent moisture getting in. i will post the article if i find it again.

 

Thanks, I would be very interested in reading about the process.

 

Looking at some heavy weight cat trawlers to get some ideas re a similar steel boat....

http://mooneyboats.ie/portfolio-view/mv-coastal-cat/

 

Epoxy and mat together isn't normal, neither are bubbles or sanding between layers. That sounds more like inexperience than an inherent glassing problem.

 

Do not forget about flotation.......................................

 

I was under the impression that you had to sand between the different layers of epoxy to get good adhesion; is there a sort of waxy bloom that forms in the surface of cured epoxy that inhibits the next lay up sticking, and the shiny surface of the new surface that has to be keyed?

Could lots of layers be laid and wetted out if one had lots of help, or is there a limit to the how thick epoxy will go before it overheats?

 

I did notice that the hulls didn't look exactly slim; is this the cost of creating enough buoyancy to support all the weight of the steel, and what would that do to efficiency?

 

Bonito boats in Holland do a large steel 15 mtr Cat kit; more for protected waters.

https://www.bonitoboats.eu/catamaran_vessels/6198/beaver_1500_600.html

And an extended wheelhouse version: https://www.bonitoboats.eu/catamaran_vessels/6240/beaver_1580.html

 

+The least expensive way is to make sealed air pockets (spaces) in the boat. measure to get the number of cubic feet as each cubic foot will float 62 pounds in fresh water and
66 pounds if salt water. Air has no weight and is free so the cost is the material to seal off the spaces. This is one reason why you see few small steel boats. Weight......

 

I think the boden steel design has a steel bulkhead that separates the forward cabin from the hulls, and another at the engine room ; waterproof doors could easily seal off these areas when underway adding extra security against flooding .