Petrel Build: 07 Installing the Keel Strips [video]

Nick Schade writes:


On this Petrel I chose to do a "side herringbone" stripping pattern on the bottom. This involves running strips down the keel line and then filling in on either side.

Strip planked bottom patterns
This illustration is from the book "Building Strip-Planked Boats"

The first step to this pattern is installing the keel strips. These strips run down the centerline of the bottom, one strip on either side. They run all the way from the stem at the bow to the stem at the stern. Near the middle the meet at a relatively shallow angle and at the ends where the keel is more deeply "V"ed they come together at quite and accute angle. These different angles need a rolling bevel to produce a tight seam along the keel.

To determine the angle of the bevel, I started by installing some scrap strips vertically on the center line. By butting the side of the strips against these scraps I get a visual on the necessary angle. By matching the gap between the top of the strip and the scrap I can plane the appropriate angle.  I did this most of the way down the length of the boat, but at the ends where the angle is more severe and I can not clamp the scrap strips due to the end forms, I have to freehand the angle.

I twist the strips to their approximate orientation and then holding the face of the block plane on a vertical plane I shave away the edge and inner surface of the strip until I get a smooth tight joint between the two adjoining strips.

Due to the severe twist of the keel strips near the ends it helps to pre-form the strips into their final twisted shape. I accomplished this with a hot clothes iron. You could use a heat gun, but I've found the iron transfers the heat faster and gets the job done sooner. A little water spread onto the strip accelerates the heat transfer a bit but is not required.

After the strips are twisted to shape I adjust the bevel some more. Actually, you could pre-twist the strips before doing any beveling, it is up to you. Once the bevel is about right, I trim the ends to fit together with the existing strips at the stems. More beveling and shaping may be needed before gluing in place.

I clamped one strip in place temporarily, check it for straightness and then used that as a guide as I hot-melt glued the other strip in place. Then I came back, unclamped the first strip and glued it to the second strip, using tape and clamps to hold it in place.