Posted by: Wayne | October 11, 2010

Rolling bevels

The Navigator is a lapstrake boat (other than the garboard).  This means that each panel overlaps the panel below it.  The resulting lap lines look gorgeous.  The challenge comes at the stem, where the lap lines should smoothly taper from the full thickness of the plywood to perfectly flush.

There are a number of ways to accomplish this.  The method detailed in the plans is to cut “gains,” shallow ramped grooves so the planks can lay flush at the bow.  This method is beautifully detailed over at Joel’s Navigator blog.

I chose to use rolling bevels.  This involves cutting a ramp into the edge of the plywood, and continuing this in a three-dimensional manner so that the surfaces mate together.  This is much harder to describe than it is to accomplish.

The rolling bevel cut into the top of the garboard. Notice how the plywood is untouched roughly 200mm aft, and is tapered to nothing at the forward end.

The mating bevel on the inside lower edge of the lower broadstrake. Sorry for the blurry picture.

Once you have these cut and fitted, you end up with something like this:


The laps at the stem. It is kind of hard to get a good picture of the taper.

I didn’t get things glued this evening, as daylight was starting to wane, and the garage is unlit.  I did get one parting shot showing roughly how things will look once they are glued.

There sure are some pretty curves in the bow. It is really narrow down low, and quite full higher up.

That is all for today.

 

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Responses

  1. Hi Wayne,
    I really like your explanation and photos of your rolling bevel gains. I remember reading about them a long time ago, but it sounded so complicated that I gave up on them. You make them look easy, or at least easy to understand! Great info, thanks!
    -Joel


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