I mentioned in passing a few entries back that we measure the angle between the frames and the planks along the planks’ length, and then bevel the edge of the planks so that they snug up tightly against each other.  Just in case you were wondering how we did that, here’s a quick tutorial in marking out and cutting a rolling bevel.

First, you use a nice little bevel gauge to measure the frame to plank angle.   The brass one in the photo here was a first year project at IYRS, and it’s one of those tools that I just keep in my watch pocket all the time.  All it does is open up to the angle you’re measuring and stay there until you fold it closed again.  Pretty simple, yes?

So, you measure the angle at a frame, lay your bevel gauge against the straight edge of a scrap of wood (now called a bevel board), and trace the angle onto the wood with the pencil that you always keep tucked behind your ear.  Then you write the number of the frame next to your line.  Move a few frames down, repeat until you get to the end of the area spanned by your plank.

Eventually you’ll get a scrap like you see on the left, with tons of little angled lines drawn on it. The straight vertical line is drawn exactly ¾” from the edge, and it represents the thickness of your plank. Now, take a small combination square, and mark 90 degree lines from the edge of your scrap to the intersection of each angled line with the vertical line.  Now you’ve got the scrap you see in this photo.

What you’ve done here is draw very precisely how much wood will need to be removed from the edge of the plank to create the bevel angle at each frame.  It looks like a series of little triangles with the flat side of your bevel board as one side of the triangle. That’s the side we’re interested in, because it shows how much wood needs to come off of the plank face to make the mating edge match your bevel angle.

Let’s look at it in action.  Here, we’re marking out how much wood needs to be removed at the point on the plank that lies up against frame 43.  Line up the bevel mark for frame 43 on your bevel board with the upper edge of your plank like this:

Tick off the width of the side of the triangle resting on the plank.  You can see I’ve made a little mark on the plank corresponding to this width.  Go down the plank, ticking off these distances as you go at the proper frame locations.

Once you’ve done that, take a batten and connect all these little tic marks.  You have to be precise here, because you’re dealing with distances that are usually an eighth of an inch or less.

Next, flip the board up so that the edge you’re beveling is facing up.  Make a bunch of pencil lines across this face of the board. These lines help you to see what’s happening when you’re planing.   The line that you just battened out is now on a vertical face of the board, and you’ll be planing down to that line.  In this example, that line is on the right side of the plank. So, start planing just a little bit at a time along the right edge of the plank with your plane slightly angled down to the right.

Now you can see why those lines you drew are so handy.  As you plane, you’ll be able to track how close you’re getting to the left edge by the disappearing pencil lines.  The idea is to connect the line you’ve drawn using your bevel marks with the left edge of the plank.  So, you’ll plane just down to the line on the right and just barely touch the left edge of the plank.

Here’s what it looks like before you start planing from another perspective.  You can see that battened line just below the edge of the plank.

And here’s that same area after planing.

Now you’ve got a bevel!  Since the depth that you plane down to changes along the length of the plank, you’ll have to subtly shift the angle that you’re holding your plane as you go.

Good job!  Now do that with each and every plank that you put on the boat.

This whole rolling bevel thing is something that tends to frighten new boat builders.  I can say from personal experience that it’s more than a little intimidating to have to roll your plane smoothly through maybe 2 degrees of angle change along along length of planking.  However,I’m also here to say that with practice, it starts to feel like No Big Deal.  So, if you’re working on your own project that involves rolling bevels, and you find yourself suddenly becoming motivated to organize your garage, attic, silverware drawer… quit stalling and get to practicing!