(or Getting to the Stem of the Problem)
by Sherwood Heggen
Just when you thought everything was going well, you didnt want to find a problem like this!
It all started while you were taking a look at the haggard condition of your boat. It was time to strip, stain, and varnish, detail the engine, put in new upholstery, and… In the shop, you pull the hardware and underneath the
cutwater you see something odd. The stem has vertical cracks at the bottom. You pick at it and find that the wood doesnt seem real hard. In fact, you pick away splinters of wood and realize the bottom of the stem is rotted. Maybe that is where all of the water was mysteriously coming in. The cosmetic restoration just got ugly. You are going to have to do woodwork.
One of the most confusing and possibly most difficult parts to duplicate on any planked boat, whether it is a runabout or a cruiser, is the stem. This curvaceous piece of hard oak mockingly defies you to make an exact copy. Yet, if the stem on your boat is broken and rotted, it must be replaced. Anxiety sets in. How does one proceed?
Now, let a warning come to play here. With a rotten stem, there may be other frame members that are also questionable. You may want to investigate more deeply into the condition of the rest of the bottom and framework. If you have to suffer, get it all done at the same time. Also, duplicating a stem most easily will require more than simple hand tools as will be described later on. Make sure you own or have access to the tools necessary to do the job.
Before proceeding, here are a couple of suggestions to aid in your success. Work with sharp chisels. You might want to resharpen them somewhere along the way as you cut the rabbets. Also, it wouldnt hurt to practice on a piece of scrap 2X6 pine to get an idea of what to expect.
To start, you must get the old stem off the boat. That can be a bit difficult, especially if the bottom is in place. To remove the stem, remove the screws and nails through the frame, topside/bottom planks and battens as far back as necessary, probably back to the second frame. Spread open the topside/bottom planks as necessary to gain working room to remove batten to stem nails and the bolts holding the stem to the forefoot or gripe. There will be screws holding the sheer clamps to the stem. Remove the nuts from the bolts and drive the bolts out. With all of the fasteners cleared, remove the stem. Each boat will have its peculiarities for removing the stem, but with a little imagination and determination, it will come out. Just dont wreck anything you dont want to fix.
You now have a rotten stem in your hands. The stem will probably have parts loose or missing, especially at the bottom where rot or cracking is more likely. Save as many of the stem parts as you can. Clean everything well and glue them back in place to restore the size and shape as close as possible.
Now begins the interesting part that you are thinking is next to impossible to do – duplicating the stem. Start by cutting a blank of new white oak slightly larger than the old stem using a bandsaw. With a thickness planer, bring the blank to the proper thickness. Lay the old stem on the new blank and trace around it carefully with a pencil. Carefully cut it out with a band saw making sure the blade is perfectly 90 degrees to the table.
Lay the old stem flat on your workbench. Take a piece of masking paper (available in a home supply store paint department) and tape it in place over the stem with double stick tape. You do not want this paper to shift as you rub the sharp edges of the rabbet through the paper with a #2 pencil, leaving the mark on the paper. This is no different than taking the image from a penny by laying a piece of paper over it and rubbing it with a pencil. Carefully done you will have a perfect image of the rabbet. Also, rub the pencil on the aft edge of the stem to create a reference line for alignment of the pattern on the new stem blank. This paper pattern can now be transferred to the new stem blank by laying the paper over it and aligning the aft edge reference line with the aft edge of the new stem blank. Be as accurate as you can in placing the pattern. Again, use double stick tape to attach the pattern. To transfer the lines to the new stem blank, make a small hole with a small nail and hammer every inch or so on the rabbet edge lines. If the line takes a tight curve, you may want to space the lines as close as necessary to maintain the correct flow of the line. When you remove the paper, there will be holes that will allow you to play connect the dots giving you a near perfect duplication of the fore and aft edges of the rabbet. There is one more line you need to transfer. That line runs between the front and back rabbet lines and represents the bottom point of the rabbet. It is important to place it properly to obtain the correct angle of the rabbet. To do so, mark off lines perpendicular to the rabbet edge line on the old and new stem at 3 to 4 inch intervals. Now measure from the forward edge of the rabbet on the old stem to a point directly above the deepest point of the rabbet. Transfer that measurement to the same point on the new stem blank. Continue transferring all measurements for this line and again connect the dots. When finished, you will have three lines drawn on the new stem blank. You will be cutting the material out of the blank between the two outside rabbet lines in the shape of a V with the point of the V at the center line. You should now have in front of you what appears in the picture below (#1).
The tools required for the cutting of the rabbets are chisels one quarter to three quarter inch in width, a mallet, small metal ruler and/or a dial caliper, a small rabbet plane, and clamps. Begin by firmly clamping the new stem blank to a sturdy work bench. At the first measured point, chisel a notch wide enough to insert your ruler to measure to the
bottom of the rabbet at the center line. The notch should be chiseled straight down at the center line and back from the forward rabbet line. This will allow you to perfectly place the bottom of the rabbet at the center line. Continue chiseling a notch straight down at the centerline and back from the forward rabbet line until the correct depth is reached at the center. Then move on to the next measured point and repeat the process. (See picture #2.)
After the notches are chiseled at each measured
point, mark the bottom of the notch with a pencil. This is a reference mark to indicate the bottom and the angle of the rabbet at each measured point. Now chisel the back side of the notch from the aft rabbet line to the bottom of the notch. Be careful not to destroy the reference mark at the bottom of the rabbet. With that finished, mark the bottom edges of the back notch with a pencil as you did with the front notch. From here on, its more fun. Remove the remaining wood from between the notches following the forward and aft rabbet lines and the reference marks. This is done with a chisel, but to hurry things along, a Roto Zip or a trim router with a small bit will remove wood very quickly. Just dont get carried away by how fast all the wood is going away and cut past the rabbet depth. And, most of all, be careful! Big gaping wounds from a chisel or a spinning router bit dont hurt at first. Continue with a broad chisel and a rabbet plane to finish the rabbet. Now all that is left to do is to flip the new stem over and repeat the process for the other side. Be sure to make a separate paper pattern for each side. The V shape at the front of the stem can be cut after the stem is in place and the topside planks are screwed down.
Now, dry fit the stem in the boat. It should look like picture #3.
Be sure the fit is tight at the stem/gripe and the planks fit well in the rabbets. If all
is well, clamp the stem to the gripe. Drill the holes for the bolts from the backside of the gripe into the stem for perfect hole alignment. If you feel everything fits correctly, remove the stem, apply a bed of 3M 5200
to the adjoining surfaces on the stem/gripe and bolt them together. Install screws into the stem through the sheer clamps and seam battens. Screw the planks in place and you are done.
If you have been careful and skillful in the making of the new stem, it will give you great satisfaction and relief knowing the job is done. You can go on to the more simple things. Say, did you notice the chines have a couple of soft spots? Oh, and look at the aft ends. They are all dried out, and dare I say, rotten.
Next time, tune in for laminating new chines. Until then, as always feel free to call me at 715-294-2415 or e-mail at Heggensj@Centurytel.net with any questions and comments.