Buttons

 The boat has 'tholes': squared U-shapes which hold the oars and form the pivots, or anchor points, against which the force of the stroke is applied. 

Our thole

Since it doesn't swivel the way a 'modern' rowlock does, the anchor point on the oar must be constructed so that it maintains (only) a single point of contact. This means that these oars need specially shaped 'buttons', which maintain that contact through the stroke and also continue to locate the oar between strokes. It's made more complex, because the oar needs to be feathered (turned so the spoon or blade is flat, parallel to the water) between strokes.

The button wraps around the back and the underside of the oar.

Some well-used buttons

Step 1: Cut rectangles of leather to be combined (laminated). Making these a little oversized will help when it comes to shaping the button.

Step 2: Clamping them together so they would conform to the right shape made it easier to assemble when it came to gluing.

Pre-shaping

Step 3: Using clingfilm to prevent glue getting onto the sleeve, the pieces of leather are glued to each other, building up the thickness of the button. Since the oar tapers along its length, I was careful to build the buttons in the right place to give me the correct inboard measurement, so they'd conform perfectly to the shape of the loom when they are attached permanently.

The leather I have is quite thick: 6 layers has given me the 1-inch depth I was aiming for.

The pieces of leather, glued in position.

Each construction is then firmly taped and clamped in position while the glue sets. Again, clingfilm was used to separate the binding tape from the leather itself. 

I used our usual West Systems epoxy, mixed with some sawdust to match the colour of the leather. This means that the buttons are now quite stiff. A more flexible glue might have worked: several people recommend PVA, but I am keeping in mind that we'll be rowing on salt water most of the time.

Once the glue had set, I shaped each button using various very noisy tools and some fine sandpaper. I am guessing at the profile of the button where it touches the thole, but I suspect that, with use, they will wear to the right shape. 

The skiff clubs on the Thames put a brass plate under the sleeve into which a couple or three bolts are driven, to help maintain the position of the button under pressure. Not having the ability to make such refinements, I have made the buttons a little wider than usual. That, the strength of the epoxy and our commitment to rowing with minimal effort should mean they stay in place and hold their shape.

The first pair of buttons.

Once I am happy with the shape, these will be screwed to the oar, through the sleeve, probably with a bit of PVA glue to help stabilise them. 

The construction and attachments of these buttons is one of the most critical parts of the whole build, as it will affect the whole experience of rowing the boat. I admit to being a little nervous...