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Bow Plate Fabrication

Posted: Tue Jul 11, 2017 5:00 am
by speedracer
I am building the Monaco (see my string "Monaco Restart" in the Power Boat section). I am trying to figure out how to get the bow plate made. No one around here could handle such a task. I was wondering if anyone knows of a firm that might fabricate these if a wood or fiberglass pattern were sent to them.

Any help will be greatly appreciated. Chris.

Re: Bow Plate Fabrication

Posted: Tue Jul 11, 2017 5:22 am
by DrBryanJ
Chris, do you mean a cut water? If so, search to forum for cut water mike. Somewhere there is a video of instructions on how to make you pattern.


Re: Bow Plate Fabrication

Posted: Tue Jul 11, 2017 5:46 am
by Bill Edmundson

This guy can help you.



Re: Bow Plate Fabrication

Posted: Wed Jul 12, 2017 6:36 pm
by speedracer
Yes, that what I mean. I built industrial complexes so I's still not up on the boating terms - sorry. Bill, I have sent a message to your suggested person. I'm sure he can help me. Thanks.

Re: Bow Plate Fabrication

Posted: Thu Jul 13, 2017 4:54 am
by Bill Edmundson

I think we were all talking about the same guy.


Re: Bow Plate Fabrication

Posted: Thu Jul 13, 2017 8:36 am
by Jimbob
Jim Thorpe of Buffalo Metal Works makes cutwaters also.
I had him make my reproduction rub rails, and re-fabricate a fairleader to match the shape of my bow. He does excellent work!
Here's his email:


Re: Bow Plate Fabrication

Posted: Thu Jul 13, 2017 9:27 pm
by Kevin Morin
I've only got Riva's and the Canadian/Lake Muskoka books as reference on wooden run-a-bouts' cutwaters and it appears most were cast aluminum then polished? So my remarks are only speculation- however, having worked in the "Miracle Metal" for a while I'm sure these remarks are germane.

The cutwater could be made of welded alloys instead of cast- by using 1/4" or 3/8" plate (1/2" ??) plate cut to the two profiles. The first profile would seem the main stem Profile View curve (or line if that is the case?) and the second would be the after profile of the cutwater's edge on the plank.

To make these of welded aluminum (5086 or even 6061 alloys) instead of casting them- you'd have to be sure the curves were lofted at the Plan View bow topsides angle of intersection; but the profile curve of the bow stem needs to be taken into this form. That is not hard- by using one set of V frames for the Plan View (angle of the topsides) and one single curve of the bow stem in Profile- the boat builder could send any aluminum welding shop these two sets of templates.

1/8" ply for both would work fine. By taking off the Plan View "V's" from forefoot to sheer- a series of three or four narrow V's would allow a pair of vertically curved 'sides' of the cutwater to be spaced correctly. With a hot glue gun, the fab shop could simply assemble the several pieces of plywood into the form of the bow's topsides at the bow stem.

Now, putting a paper pattern on this model (or using the side piece before gluing up) would allow a pair of the thicker metal plates to have both the curvature and the angle to hold the two pieces. This single side pattern, copied as a pair- would then be held to one another at their leading edges tack for a weld. These two plates would form a perfect weld fillet, and a pair of Plan View topsides angle V's would act to hold the two pieces/sides of the cutwater while it was tacked then welded. By filling the weld, formed by the V of lead edges, full and "topped over" a welder could easily round over the weld fair to the two cutwater sides.

Then the after edges of the contour cut plates, now curved to the bow stem's profile, could be routered using round over/bull nose carbide bits and the entire surface sanded, buffed and then polished to a fine grit (mirror).

This would not be a very hard project in aluminum, might be a bit more in steel that was chromed, or SS if that was considered?

I'm basing this set of remarks on the Riva Book and the Ditchburn and other Lake Muskoka builders, converting their methods and photos to a welded product that could be done by a wide range of shops, instead of limiting the cutwater to a casting-based piece of metal.

2 more cents.

Kevin Morin
Kenai, AK