How useful is a CNC machine for boat building?

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How useful is a CNC machine for boat building?

Post by nybhh » Tue Sep 11, 2018 1:23 pm

I'm contemplating starting a 24' Tahoe in the next 12 months or so but would really need a larger shop than my garage setup which fortunately is already in the planning stages and and doubly so, not too late to add another foot or 2! :wink:

Anyway, My brother has a CNC machine and I was speaking to him about this potential project last night and he suggested it might be a useful tool and he could help me put together a 4x4 or a 4x8 for a surprisingly reasonable amount of money. I've started reading Boatbuilding Manual by Robert Steward and have a copy of The New Cold-Molded Boatbuilding by Reuel Parker as well as reading a bunch of you guy's build threads but I don't really have a deep enough understanding of the full process yet to understand where a mill might be useful and how helpful it would actually be.

I wanted to ask if any of you have used one or what your opinions are on them for this particular endeavor and if so, what size would be appropriate? Sure, a 4x8 would be great but that takes up a LOT of additional floor space unless it could double as a layout table or something. I hadn't really considered one before that came up last night but I'd probably need to incorporate it into the floor plans soon to make sure there would be space.

I realize some of the purist among us may scoff at the idea also and that's cool too, I get it.


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Re: How useful is a CNC machine for boat building?

Post by TomB » Tue Sep 11, 2018 2:00 pm

I am in the planking stage on my 23' Tahoe. The challenge I see with CNC is in the control based on a pencil drawing. The drafting is great but if the corner isn't perfect with no gaps or crossed line the machine will look for control input. You will have to re-draft the drawing into some sort of numerical program compatible with the CNC. Perhaps a CNC would be more useful on the boat interior furniture. There are 10 frames and about 5 pieces/frame plus 4 gussets. By cutting two pieces/you can create a template for the others. Many of the pieces are 3" wide boards with an odd angle cut at each end. So in the end, there are not that many pieces with a difficult shape that would benefit from prep to get ready for the CNC.

Better to spend you time tracing the tracing the pieces for one side of the boat. Saw them out leaving the line, use a stationary belt/disk/drum sander of your choosing and sand to the line. Take those pieces and trace out pieces for the other side, cut them out, stick the two pieces together with carpet tape, use a pattern router/bit to exactly duplicate the first set of pieces. You will quickly create a stack of 45-50 pieces that make your frames. Then stick 'em together, put the gussets on overhanging the outside edge, get out the pattern router/bit and clean up the edges. All done with the frames, no big machine investment, no big time investment.

Spread the frames out, imagine the boat, you in it. My two cents.


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Re: How useful is a CNC machine for boat building?

Post by hoodman » Tue Sep 11, 2018 2:16 pm

I wouldn't exactly call us purists. We build plywood boats after all. I don't really care what tools you use to build your boat. That's up to you. However, I would say a good bandsaw would be a better investment than a CNC machine for boatbuilding. Something you can re-saw with would be ideal. You can use it to cut frame pieces and then later to re-saw your veneers. Otherwise, you're going to spend a lot having someone else re-saw your veneers.

I'm with Tom, by the time you programmed all the frame pieces into the computer you could easily have them cut out just by tracing from the paper patterns. Once the frames are on the building form that becomes your pattern. You could use it to make all kinds of parts after the flip, though. If the CNC can cut metal perhaps you could program in all sorts of parts like the hard-to-find or expensive ones. Like the windshield brackets. Or go do those on your brother's machine. :wink:

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Re: How useful is a CNC machine for boat building?

Post by nybhh » Tue Sep 11, 2018 2:23 pm

Thanks Tom. Yea, you would need to get everything into CAD. I work with CAD and 3D software professionally and I'd probably "pre-build" the project in 3D anyway to better understand how everything comes together in 3 dimensions. My shop time is pretty limited but I have plenty of time in the office where I often "build virtually" and and I've found that makes my shop time more way more efficient. Just sort of the way I'm wired.

Anyway, yea as far as just the frames go, probably isn't worth it just for that. Interesting about the interior though. If you had enough Z-axis depth, one could design an interior with a lot more depth & relief, curves, fillets, etc. Even some inlays might be nice. I do have a decent bandsaw already so that is covered. Really a good jointer is my last major piece I still need. My brother's mill is a metal setup so I'll enlist his help for any metal work and I do know he works with stainless.

Thank you both for the input. Sounds like it probably won't be that big of a time saver pre-flip at least.

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Re: How useful is a CNC machine for boat building?

Post by Bill Edmundson » Tue Sep 11, 2018 3:21 pm

For a one time build CNC is a waste of time. I've used 3D cad a lot! I was one of the first groups to do a entire power plant in 3D cad. I love it. But, for a one time build, put your work in the boat.

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Re: How useful is a CNC machine for boat building?

Post by Milhouse » Tue Sep 11, 2018 5:01 pm

I have a Laser and CNC and I would not use them for a one off build for boat or most fine woodworking projects for the points mentioned above.

I do like the laser for making templates from my 3D models though :)
Template that was laser cut
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Re: How useful is a CNC machine for boat building?

Post by Hercdrvr » Tue Sep 11, 2018 7:49 pm

I can’t even spell CNC and managed to build 2 1/2 boats so far.
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Re: How useful is a CNC machine for boat building?

Post by nybhh » Wed Sep 12, 2018 10:12 am

@milhouse that's pretty cool. Thanks again for the input guys. Sounds like I'll pass on his offer for now. Space would be tight anyway.

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Re: How useful is a CNC machine for boat building?

Post by watkibe » Mon Oct 22, 2018 3:09 pm

CNC is a whole art and science of it's own. It is very fast and accurate for industrial scale production, but a one-off project is usually not a good application for this technology.
Plans must be in some kind of auto cad format, then translated into g-code, and then uploaded to the machine. Tooling, jigs, and fixturing are all required to be near-perfect. Each of these steps requires its own skill set.
There are boat kit builders who are CNC cutting boat kits in plywood and steel/aluminum with great success; again, this is industrial scale production.
From the Great Pacific Northwest !

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