Sunday, 9 May 2021
The mast is the very last piece of the boat for me to make. It is quite satisfying to see the wood racks empty and each timber item on the cutting list ticked off.
The mast is a tapered hollow box, made from from four staves.
Each stave consists of two or three pieces of Douglas Fir joined together by scarf joints.
The length of a scarf is ten times the thickness of the timber, which results in easily managed joints.
However, I found that that the scarfs on my pieces of stave have been cut edge-to-edge rather than face-to-face.
This means that the joints on the 3" by 3/4" side pieces will be over 30" long, instead of 7 1/2".
This in turn means that one joint will require nearly all my G cramps to hold it in place while it cures.
I set up the first stave for a test fit of the scarf joint. Here it is.
It looked good, but it's going to take a long while to make all four staves if I can only glue one scarf at a time.
I cleaned up the faces of the scarf with the block plane and glued it together.
Sure enough, it took fifteen cramps to secure it properly.
I may have to invest in a lot of new clamps which I may never need again!
The sanded spars were taken inside and laid on the empty wood racks which are now a useful work surface.
The final task in making the tabernacle and boom gallows was to round over their edges.
I did this outside because it make so much dust and mess.
I used a 1/4" bearing guided round over bit in the router. This is it.
This is the tabernacle being routed.
I only rounded over the outside edges, but I may have to do the inside too at some point.
This is the boom gallows being routed.
And here is the nicely rounded edge.
By tapping the piece of stock down onto the dowels I marked the exact distance between their centres.
I scribed a horizontal line along the gallows, exactly level. This would be my datum line for checking that the gallows was horizontally level on the drill table.
That's it! I now have 55mm deep holes in the boom gallows in hopefully exactly the right place. We will see when we are fitting out.
The pivot and drain holes were drilled with the drill guide to make sure they were perpendicular, like this.
The manual says to use a piece 1 1/2" thick, but I thought that that would be too skinny - especially when 1" (25mm) holes are drilled for the support poles.
The two top bolt holes for the tabernacle were drilled from the outside, using a drill guide to make sure they were perpendicular, like this.
The two bottom holes were then drilled from the inside, as here.
I then loose-fitted the tabernacle, using the centre line to make sure it was in the right place, like this.
The bolt holes were then marked in on the back of tabernacle from inside the cabin.
The tabernacle was disassembled and the bolt holes drilled in the back piece on the pillar drill, as here.
The mast occupies the whole interior of the tabernacle so the bolts have to be countersunk. I did this with a Forstner bit.
The back piece was then bolted in place to check fit.
That looked OK so I reassembled the tabernacle and made a test fit, like this.
Large washers are used the inside the cabin, to spread the load on the backing plate. As in this pic.
Then I drilled a small pilot hole in each location, just to check and be sure about where the bolts would go on the inside and outside cabin wall.
The side pieces were marked out using the pattern provided and then cut and planed to shape, as here.
I had taken the angle for the bottom edge from the boat rather than the pattern, because patterns rarely conform exactly to the manufactured component.
The next step was to fasten the pieces together to form the tabernacle. I decided to use temporary screws since I would need to disassemble and reassemble it a few times in the process of manufacture.
The bronze screws are a fraction fatter than the temporary screws, and the 1 1/2" bronze screws are not long enough to securely join the strengthened sides and the back piece.
I cannot glue the pieces together yet because they will need to be taken apart again to drill the bolt holes in the back piece.