A New Stem and Gripe

The Stem and Gripe together make the Forefoot of the boat.  This is the curved part of the bottom that provides the transition from the stem to the keel.  It needs to be a formidable piece of the boat because it is the piece that parts the water as the boat makes its way.  It takes considerable pounding, and in an older boat, almost always has some rot in it.  That means it’s going to have to be replaced.

Since we have the plans, we could loft the boat and then take off the curves to make a new stem/gripe.  But we have a pretty good pattern (albeit with a little rot here and there) in the old one.  Using a sheet of glass and some clear plastic from the art store, we can draw out a pattern and transfer that to properly dimensioned white oak to make a new one that’s better than the old–better because it’s made of rot-resistant white oak.

So the first step is to lay a piece of 1/4″ glass over the old part and trace its lines onto a piece of clear mylar.  Of course you want to get as much information as you can on this tracing, including bolt locations, bootstripe, etc.  And make sure you are looking straight down on the part when tracing to avoid any parallax error.

Then take your new pattern and transfer the lines to your new wood.  You do this by tracing over the new mylar pattern with a “pounce wheel”, which you also get at your friendly art supply store.  You can see in our example that we made sure to avoid any sapwood in the new pieces.  Sapwood is much lighter in color and contains dried sap and sugars.  Including sapwood in your boat is like a flashing neon sign for rot spore–bad news if you want to keep your boat rot free.

Once the pieces were cut on the bandsaw, it took a little time to fit the joint between the stem and the gripe.  You need a good, solid joint here that, once slathered with bedding compound, will not allow ingress of any water.

Once we got that joint in good shape, the stem and gripe blanks were bolted together and fit to the breasthook.  Then it was time to look at the curve of the whole assembly and make sure it would be fair with the keel joint.  As you can see, we had to glue in a shim or two, but there’s no shame in that.

Finally it was time to carve the rabbet.  That’s the groove that runs lengthwise along the piece for the bottom planks to rest in.  That’s really a topic all in itself, but we’ll show it here.  To make a long story short, you use the lines you’ve traced on to your blank from the old stem/gripe assembly.  Using those lines, you have at it with your chisel and carve out the rabbet.  It helps to have a test stick, called a “fid”, that is the same thickness your planking will be to test how it fits in the groove as you carve it.  With a tough wood like white oak, you have to pause a few times to sharpen the chisel.  You can definitely tell the difference a sharp tool makes here.

Then clean it up with a plane, sander, Fein multimaster, whatever works.  You’re done!