Outwales: Bending Wood the Hard Way

A little review. The top most part of the hull, the part you would grab when pulling yourself from the water into a small boat is called the gunwale, pronounced "gunnel". On a wooden boat, it usually consists of an inwale and outwale. On my boat, the inwale was installed when the boat was upside down because it supported the final run of the strips used in the hull.

Now that the boat is right side up (why is it "upside" down but not "upside" up?), the outwale can be installed. Because the inwale had to support the hull before there was any other structure, I wrapped it around the stern as one piece, then scarfed in second pieces on both sides to extend up to the bow. But the outwales were installed from stern to bow in one piece: 16' of 3/4" X 2" ash boards with their ends butted together on centerline at the stern.

First the paint had to be sanded off the hull where the outwale would go. These two pictures show how I painted roughly to the gunwales (remember the hull was upside down when I painted it).

Because the hull tapers or bends away from the gunwale, I sanded off the paint off to only about 1" down from the gunwale. There is a gap between the bottom of the outwale and the hull that will be filled with epoxy at some point (maybe!).

Remember too that the outer hull has a layer of fiberglass that goes up to the gunwale, so the sanding was down to the glass.

The outwale extends from the center of the stern, bends around the fantail, dips down as it goes along the side of the hull, then curves back up and in as it reaches the bow. This means the single 16' piece ash on each side has to be bent in a compound curve.

When bending a rectangular beam, bending it across the smaller dimension is known as the "easy" way, and bending it across the longer side is known as the "hard way". The outwale had to be bent the easy way around the fantail and the hard way along side, then both ways as it curves up to the bow.

I tried 3 different methods for softening the wood so it would bend, and at least 3 different ways to actually make the bends. 

I had tried steam bending but the wood didn't seem to get hot enough. I used the heat gun method on the frames and for some of the bending of the outwale which sort of worked but left burn marks. The best softening method turned out to be one wrapping the wood in rags then poured boiling water on the rags for more than a 1/2 hour. When the wood seemed to get soft, I then tried various methods for actually making the bends.

The picture above and the two below show bending attempt #1, which was to clamp the outwale to the gunwale and pull up on it. The problem with this method was that it put a very large force on the gunwale and actually cracked the hull where the clamps were.

I put the spring scale in the lift system so that I could sort of tell when the wood was getting soft. The force would go down slightly when the wood got soft.

Attempt 2 (kinda' hard to see in the pic below) was to clamp the end of the outwale in my bench vise, secure the workbench to the wall so it can't move, then pull on the end of the outwale. Look closely right in the center of this picture and you will see a large beam clamp clamped to the outwale with a string at the end of its beam tied to the post in the boat. This was needed because the outwale tended to twist. The clamp held it flat-ish. This worked quite well. The string at the bottom of the picture is the one that pulled on the board.

At the stern the bends are far tighter, but the outwale was being bent the easy way. Also I tapered the last couple feet of the outwale to match the thickness of the fantail. It ended up being a square beam and so was relatively easy to get it hot all the way thru and bend it. The first bends started the outwale around the fantail.

First I bent this part by just clamping it to the gunnel, but the bend sprung back too much, so I reheated the wood and stuck a little block in the middle of the bend. This pretty much worked.

The hardest bend turned out to be the last little bit at the end. The bend wasn't as sharp as around the first part of the fan tail, but it was hard to get just the end to bend. The method shown here worked for the port side, but I just couldn't get the starboard outwale to bend right at the end. I ended up sanding down the inwale a bit to reduce the bend and it now fits well enough.

So, after the bends were close enough I clamped the outwale so the stern end aligned exactly on the centerline, then clamped it all the way (most of the way) to the bow with the outwale flush with the top of the inwale. The next step was to drill the holes for the screws.

I decided to use bronze oval head bronze screws with Frearson drive (slightly different than Phillips head) to screw on the outwales.

This is the port side outwale, glued and screwed in place. I started some sanding on it, but it will need more sanding before varnishing.

Starboard outwale (on the left in the pic) is glued and screwed. The clamps help hold the outwale tight in a few places while the glue dries.

The outwales are not yet attached at the bow. I haven't figured out how to bend and shape them to match up against the bow stem. The orange clamps are currently holding the outwales up flush with the gunnel.

I have also installed the forward floor! Very exciting and will make working inside the boat way easier. The aft floor is next, along with the tank pump system and bilge pump.

The floor is 3/8" four-ply AC plywood. I epoxied it to the floor frame and added bronze ring shank nails. The weights and bucket of water help to hold the floor down against the frame while the epoxy hardens.