Bob Easton

#$%*&!!! DANG!

I don’t have the 7/8″ cut copper tacks (also called clinch nails) needed to attach the garboard planks. I ordered all of the fasteners some months ago, but had forgotten that this particular size of tacks were out of stock. Apparently, they are a scarce size. Three of four providers still list them as out of stock. The fourth has a minimum order quantity of 50 pounds, which is 49 and 1/2 pounds more that this boat needs. A couple hours searching found a roof gutter firm in Pennsylvania that has them in reasonable quantities. They’ll be here in a few days.

ADVICE: If you think you have everything you need for your current project, stop right now and go double check.

Clinch nailing is not very common these days, and I have never done it. I watched some other guys do it at the Wooden Boat School, but didn’t get into it myself. So, it was time for some practice on scrap lumber. The concept is simple. Use a nail that is a bit longer than the pieces of wood being joined. Cause the tip of the nail to turn and bury itself inside the wood. I imagine many of us have had experience with the tenacity of unintentionally bent fasteners. They don’t come out easily. I’m guessing that some ancient bent nail victim said, “Hey, I have an idea…” and came up with the idea of clinching.  The result is indeed tenacious.

Boat builders use copper tacks in pre-drilled holes, a lightweight hammer, and a clinching iron. The iron has enough mass to do the job, and is interestingly curved to get right up close to a boat’s many non-flat surfaces. The process is simple. Place the iron at the spot where the tip of the nail should emerge and then hammer the nail in place. The tip hits the iron and goes back into the wood. Watch this video of Brahm and his friend doing clinch nailing at Hillmark Boats. It is as simple as it looks.

Before you ask why my clinching iron looks like it’s wrapped in packing tape, I’ll answer. Yes, it is. Mine is iron and will leave dark marks. The tape helps avoid the unsightly marks. The other alternative is a bronze clinching iron. The price difference between iron and bronze will by a couple of cases of Snickers bars.

As always, click on any image to see a larger version.

Now, I’m curious about how well the joint holds and what the nails look like (inside the wood) when clinched. So here are a couple of destructive tests. One is joining a 5/16 inch thick board with a much thinner piece. I used 3/4 inch tacks, which I obviously have, and found that a curl of almost 360 degrees is formed inside the wood. It took a good bit of effort to pry the boards apart and the curled ends of some nails refused to release the fibers they had trapped. Yet, I think this is less than optimal because the curl traps too little material.

The other test is again using 3/4 inch tacks, but this time joining two 5/16 inch boards. This time the end of the tack made a 180 degree turn, but no more. It trapped more fibers. This joint was very difficult to break, and is much more tenacious than the one with the full curl.

These tests show how the length of the nails, in porportion to the wood being joined, is important. Too short, no clinching. (You don’t get to see that test.) Too long, we get a circular curl. Just right, a 180 degree turn and a strong clinch. Seeing these results, I’ll believe the designer’s specs and wait for the rare 7/8 inch tacks.

Slow and deliberate are good adjectives for my boat building methods. The “deliberate” is because I’m new to this, learning as I go, and approach unpracticed tasks with a little trepidation. The “slow” is just, well, slow. Since the last posting, I’ve removed and plugged 17 knots in each of the garboard planks, trimmed the upper edge of the planks to land precisely on the knuckles of the frames, and steamed the planks into place.

The garboard planks on this boat have a lot of twist (maybe I said that before). Harry Bryan, the designer, suggests that Northern cedar probably won’t have problems with the twist, but that other cedars might, and suggests steaming the planks.  People who build lots of boats have steam boxes for such work. If I were building a Whitehall with 48 sets of frame, I’d probably build a steam box. Yet, for only two planks, I used an alternative method.

Wrap an end of the plank in a couple of old towels. Wrap the towels with plastic. Then, saturate the towels with boiling water. Draw up the plastic wrap to hold moisture and heat in. Repeat several times, to keep the plank hot, over a half-hour period. The wood becomes more pliable and is easily clamped or fixed in place. Sounds easy. Actually, it is. My only complication was having the 4 gallons of boiling water in big kettles on a stove one floor away from the shop. So, there were many trips with a small pan of water down and up the stairs. That actually worked out well, causing the dousing to be spread out over time. Of course, there’s spill over and water on the floor. That’s OK. The shop is a converted garage with a concrete floor. I used a 30 gallon trash can at the end of a plank to catch runoff. That seemed to work OK, until I went to empty it and found only about 1/2 inch of water in it. A “hole in my bucket” had transformed the can into a funnel. Oh well, the shop floor needed a good cleaning.

Two planks, four plank ends, four separate steaming sessions, about four gallons of water each. The shop, and the kitchen upstairs, were saunas for a while.

There aren’t many clamping spots, only the mid-frame and the two bulkheads. I used drywall screws along the runs between the clamps. The drywall screws will be removed after the planks are permanently fixed and their holes will be patched. I probably used more than I needed, adding yet one more reason for the slow part of my boat building.

Next step: The planks come off, an adhesive bed gets applied and the planks go back on with permanent fasteners.

The first planks to be fitted to the boat are the garboard planks, the ones at the very bottom. They are also the planks that have the most curvature in outline and in the way they lay upon the boat. They are nearly vertical at the stems and splay out to about 30 degrees in the middle of the boat.

Finding their shape can be an adventure. The principle methods are two: (1) Use the shape documented in the drawings (if available), or (2) find the shape from the boat itself. The designer provided plank shapes in the drawings. Not all designers do this, but these look to be quite useful. One would imagine that using the shape from the drawings would be OK. Yet, success with that method depends on the framework being constructed as precisely as the drawings. That’s not always the case, and while my measurements appear to be right on, I don’t know how much tolerance is built into the drawings. Taking the shape from the boat itself is called “spiling” and is an art form of its own.   Spiling is two parts black magic and one part semi-Euclidiean geometry. The particular variant I used is the one that Greg Rössel uses.

Being of the belt AND suspenders persuasion, I used both methods. It turns out that my spiled shape fits within the shape defined on the drawings. Erring on the side of cutting the plank too large, I ended up using the shape from the drawings and sawed to that shape. Sawing was easy with the bow saw. There is a “lesson learned” with the first cut. I was focusing on staying near the line and didn’t appreciate the fact that the waste piece was hanging free going “whipity whipity” as I sawed. As the cut got longer the waste piece increased it whipity whipity whipity until it went “whipity whipity CRACK.”  Oooops!  Hey dummy, support the material and don’t let anything whip around. Fortunately, the splitting was on the waste side of the line, not into the plank.

Then it came to test fitting, trimming, and repeating until the plank fit the boat well. All of the attention was for the edge of the plank that will meet the next plank up. There’s little need to fuss with the part that extends beyond the bottom, as it will be simply planed off when the time comes. Test fitting is challenging because of the extreme bends in this plank. The dry boards cannot be completely bent into place. They will need steaming to be bent to final placement. So, test fitting is “best estimate” at this stage. Set three clamps and then gingerly “muscle” the ends toward the stems. Caution is advised since this species of cedar is known to be somewhat brittle.

These garboard planks turn out to be quite the bananas. Here is a fitted one atop the board that will become its partner. Now we see why we need a very wide board to start with.

Getting the planks attached to the boat is the next adventure. That job needs screws, clinch nails, goop, big cauldrons of boiling water, towels, plastic bags, time suspension, and maybe a helper.