Cutting the Flat

You can see the exposed end grain in this picture of the flat cut most of the way with a power plane.

Last time, I talked a little about cutting the flat along the keel so I could put a cap over it to keep from having exposed end grain there.  My friend Steve asks, “Well, exactly how did you do that?” (or words to that effect).  It did, in fact, take a little bit of doing.  So I decided to explain myself a little better in a follow-up post.

Recall the Nelson Zimmer called for a 1-7/8 inch wide flat along the keel, tapering to 1/2 inch wide at the stem.  In order to get the proper depth and width of cut, I consulted the lofting board to get some dimensions.  Remember lofting?  If not, click the link and take a look.

Lines drawing consists of the Profile View (top), Body Plan (middle) and the Half Breadth View (bottom) along with the Table of Offsets (very bottom)

First, take a close look at the lines drawing for the boat.  For this task, we’re particularly interested in the “body plan”, the drawing in the middle of the page showing sections cut through the boat at each station.  Stations 1-6 are shown on the right half, with stations 6-10 on the left.  Look at the bottom, where the keel is.

My detail lofting of the bottom of the body plan along the keel. If you look closely, you can see a paw print or two, Sadie’s contribution.

Now take a look at a detail of my lofting of this body plan.  Notice that station one shows a 1/4″ flat (half of the full width), and all the other stations are at 15/16″.  I measured along the bevel line at each station from the center line out to a point 3/16″ above the drawn flat (because my cap is 3/16″ thick).




My table of lengths I would need along the bevel angle from the centerline.

I recorded these measurements in a table and took it to the boat.  I have a string line above the boat that I can use to re-establish my centerline any time I need to.  So  I checked the centerline and then marked off the lengths along the bevel at each station.  I connected the ticks with a batten and I had my guide lines established.

Then I got out the hand held power plane and started making shavings.  I finished off the cut with a low angle block plane.  This exposed a lot of end grain wood which was then covered with a 3/16 cap, which was easy enough to bevel by using the block plane alone the hull.  I was able to use a single thickness of 3/16 for the aft section.  But from about station 3 forward, I used three 1/6″ plies and laminated them on the curve of the stem.

There you have it, Steve.

2 Replies to “Cutting the Flat”

  1. Great explanation, thanks Tim. I’ve still got the starboard side garboard to fit before I get to the keel, so perfect timing for me!

  2. Tim,

    Your boat is looking better and better. I’m definitely gonna want a ride in that bad boy when it’s done. It strikes me how much work you have to do to build a boat like that. I’d be interested in taking a look at the engine you install in the boat. What’s your estimate on completion?

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