Posted on by stuartmorgan · 8 Comments

On Setting Up, Rabbets, and Arches

Days turn to weeks, and weeks to months – two since I last posted on this blog. But I do have some progress to report!

With the aid of a laser level, straight edge and spirit level, I started fitting the moulds in place. These need to be centred accurately, set to the correct height, and strongly braced in position at ninety degrees to the centreline of the boat. The first two of these was accomplished using the laser and traditional levels, and the straight edge. Getting the moulds perpendicular to the centre line uses a simple, but ancient technique: horning.

So, what is horning or horning-in? Imagine the centre mould pivoting about the vertical strut I fixed between the hog/keel and the garage rafter. To fix it perpendicular, all I need to do is take points on the edge of mould – such as the 18 inch waterline – and make sure that the distances from each of these points to the midline of the stem is the same. An isosceles triangle. There’s no need for rulers or measuring tapes … out comes the horning batten – much more accurate.

The horning batten is simply two sticks clamped together, so that they can slide and then be fixed in position, with the distance end to end able to be finely adjusted. All that is then required is to adjust that length until both sides of the isosceles triangle match.

Cable ties, or fancy clamps work just as well.
Horning-in the middle (Station 3) mould. Checking the distance to the stem on the port side …
… is the same on the starboard side.

Step by step, one by one, the four other moulds were adjusted into position and braced, so as to be strongly held in position.

The laser level was perfect for getting the moulds level side to side and for getting them to exactly the same height. (I did use a spirit level too, just to be obsessively accurate!)

Once the five moulds were in place, I fitted the transom: a 2” silicon bronze screw at the bottom; a home made 5mm roved copper nail above, and a brass shackled bolt that provides her with a mooring eye. Sylvia was on hand to back up, while I roved the nail:

My trusty assistant.
A piece of 3mm ply (leather can be used too), with a hole that matches the rove (washer), ensures I don’t bruise the wood as I rove the nail.
Fully fitted. The saw-tooth piece of wood on the op of the transom is an idea I had to help with clamping (see below).

So, here are a few photos of the final result, with all the moulds and transom in place:

With the setting up completed, it is time to tackle the keel rabbet, something I have not been looking forward to.

The bottom-most plank the garboard, is fitted into a recess made in the keel and the hog – the keel rabbet. The photo above shows the recess already made in the stem – the stem rabbet.

Here’s a diagram of the cross-section of the keel and hog:

The left side of the left hand drawing shows the starting point, and the right side shows the recess … the rabbet. The right hand diagram shows the garboard planks in place

Using a batten, clamped in place against the moulds, I have marked the line where the inner aspect of the plank meets the hog, which is known as the bearding line. (The rabbet line is the line where the outer face of the plank meets the keel, and the inner bearding line is the apex of the recess. Sorry … too much information!)

I was worried that I had made an error with the outer edge of the hog becoming very thin at the transom. Happily, my friend Matt popped round, and reassured me that I am on the right track!

The most important thing at this stage, as in so many aspects of boat building, is to create a fair line (no flats or bumps). So, …

… while the batten is not quite touching one or two moulds, this should all “come out in the wash.”
Here’s that saw-toothed piece of wood in action – without it the clamp tends to slip when holding planks onto the transom – something I wish I had thought of in Boathouse 4!

Oh, I must also mention a fabulous event that took place towards the end of January: our son’s wedding to Stephanie. I was commissioned to make a wedding arch for them and, despite my uncertainties over its usefulness, I am pleased to say that it did form a nice centre-piece and was well received:

I do like a ‘fair curve.’

Well, I cannot put it off any longer, I have to tackle that keel rabbet now. It will be very tricky at the transom, where I have to avoid going against the grain on the hog, and splenching (tearing out) the back edge of the transom. I haven’t dared to start worrying about the stem, where I will have to narrow the hog to meet the 1st mould and creep up on the stem rabbet. That’ll be the time to “tickle and blend, tickle and blend” as I was told at IBTC.

Wish me luck!