CNC catamaran plans?

[44'cruisingcat]

Originally Posted by MaddMatt

All:

In addition to the option of purchasing a used cat, i am intrigued by the idea of building. In researching the time and hours involved, a big chunk right off the bat is printing plans, measuring and tracing onto plywood and cutting it all out. CNC machines take all that out of the equation and building starts that much faster as well as ensure perfect scarfs and cuts. It also helps see progress early on helping ensure more projects get finished.

I have found a couple of references to plans cut with CNC but does anyone know which designers have this as an option? It seems like a no brainer in 2020 but not seeing a lot of info on it

Matt

That's how I built mine. (Not plywood though) Definitely speeds things up, but it still took around 6000 hours for a 44' cat.

Some photos if you're interested:

https://www.cruisersforum.com/galler...00&userid=3477

[Dave_S]

The hull/deck should be designed as a single assembly incorporating all the internal fitout and should be assembled as one part at the same time (including furniture etc, right down to the fixing hole positions). You would then have designed a stronger, lighter, cheaper, easier to assemble boat. The time in design will be paid back many times in production. It's part of lean manufacturing and better in every way.

CNC router may be most suitable as it can cut partial depths which is very helpful to form a radius from composites where you can calculate and cut slots like those you might make with a circular saw but in this case using a cutter, down to, but not including the bottom skin layer. In this way you can bend the part untill the cuts close up on the inside to form a radius with a seemless and somewhat uniform outer face. You can also leave small tags to hold the parts in the sheet for transport to reduce the chances of damage. The scrap can be numbered to identify the parts and into which part they fit. Another advantage is you can machine a larger hole and undercut it down to the outer skin for a fixing exactly on centre and you can resin fill and drill for your correct size fixing to minimise the chance of water ingress.

IMHO the only way to go.

[44'cruisingcat]

Originally Posted by Dave_S

CNC router may be most suitable as it can cut partial depths which is very helpful to form a radius from composites where you can calculate and cut slots like those you might make with a circular saw but in this case using a cutter, down to, but not including the bottom skin layer. In this way you can bend the part untill the cuts close up on the inside to form a radius with a seemless and somewhat uniform outer face.

IMHO the only way to go.

You're describing kerfing.
If you cut the core right through to the outer laminate, the bend tends to form steps, a bit like a 50c coin.

I found it best to only cut the inside skin, leaving all the core. When you bend the kerf, the core gets compressed, making for a very smooth and uniform curve on the outer skin.