Nice Butt…Joint

(or How to Make Ends Meet)

by Sherwood Heggen

Some of the processes in boat restoration seem so simple until actually attempted. Then, the question comes to mind of how they actually did what you are trying to do. One of those processes is that of making close fitting butt joints on covering boards. You will find these joints typically at the windshield on the typical utility or runabout. They are very visible to the onlooker if done poorly. Plus, if they are not tight, water can easily enter only to remain and begin the rotting processes. In fact, the reason the covering board might need replacing is that it started to rot at a poorly done or poorly sealed butt joint. Rot at the joint will be apparent by peeling varnish and discolored wood. Usually if the forward covering board is affected, so is the aft covering board.

We are going to take a look at how to make close fitting butt joint which will ensure a watershed for the boat’s structure below.

The butt joint exists to join two lengths of planking. Done well, the resulting joint is nearly invisible, making it appear as one piece. The ends of the adjoining pieces must be cut carefully to match perfectly. Cutting the joint to fit is actually the last on the list of things to do when making the new covering board.

Let’s consider that the old covering boards are removed and are good only as a basic pattern. Cut the boards from new stock leaving the ends long that will be the butt joint. Fit them to the deck and screw them in place with a few screws to hold them flush to the deck, overlapping the ends to be cut by a couple of inches. To help keep things stable at the proposed joint, use clamps as necessary. Draw a line with a black felt tip pen where the butt joint will be. At this point it may be wise to set up a practice piece to see how this all works before committing to the one chance cut. With a back saw held at a slightly racked angle to the board, using a scrap piece of board as a guide, proceed with cutting the joint. The raked angle, which is angled back, is important to assist in holding the aft covering board down tight by the forward covering board when screwed in place. Take it slow, initially drawing the saw backwards until a kerf is developed. Then carefully saw through both boards with long straight strokes. Now remove the scrap pieces and butt the two ends together to see how the joint looks. The board ends must be snug against each other to determine if there is any gap between the two. To get them tight, slightly loosen the screws holding down the aft covering board and firmly clamp it in place. Then place a scrap piece at the end of the aft covering board and strike it with a hammer to move the board forward as far as it will go. You will know it is as far forward as it will go by a distinct change in sound as you strike the end of the plank through the scrap piece. Now, check the fit of the joint. You may see a perfectly fit joint. If any gap is detected, use a very sharp block plane to shave off the high spots and then recheck the joint, and snug it up as described above. Go slowly and you will be rewarded with a joint that nearly disappears.

To keep that joint in position and water tight, it is important to seal it, glue it, and screw it properly. Sealing can easily be done by treating the end grain with Smith’s penetrating epoxy. Allow it to cure and then prior to screwing in position, apply a thin film of 3M 5200 on the butt ends of the planks. Wipe off any excess with naphtha after it is screwed in place. It should go with out saying that butt blocks and seam battens should be replaced if any hint of rot is detected before screwing everything back together. The end result will be a water proof, crack resistant joint that will look good for many years.

With all this done, stand back and admire your work. Things done well deserve admiring. Invite someone over to help you admire it if you feel you have done exceptionally well. Let them tell you how well you did. It will make the effort of restoring rather than destroying all worth it.

If you are reading this, you more than likely are one who cares about the preservation of old boats. Thanks for caring. Your efforts toward keeping them afloat and looking good says something very positive about you. I enjoy communicating with anyone who wishes to call me and talk restoration.

I have new contact information which is as follows: home phone 715-294-2415 and email If you feel there should be an article written about certain restoration process, feel free to speak up and we’ll get it in print for everyone to read. I look forward to hearing from you.