Sunday 9 May 2021

Tabernacle | Ninth Cock Up!

I was standing in the workshop looking at the tabernacle and trying to imagine it holding the 16' mast, which I have not yet made.

Out of curiosity I did something which I should have done during installation - I took the engineer's square and set it on the deck next to the tabernacle.

I was horror struck.

It was not square. The tabernacle had a very slight lean to one side. Not much - no more than 1/16" or maybe 1/8" in 12". But that adds up to a lot over the full 16' feet of the mast. Between 1" and 2", which is clearly not acceptable.

Silly Error or Cock Up? Definitely the latter!

Luckily it would be easy to remedy the problem. I would simply plug the bolt holes in the cabin wall with hardwood dowels and re-drill the holes.

Here are the dowels glued in place.

We live and learn. Hopefully.

Mast | Making The First Stave

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!

Tabernacle | Truing Up

Having discovered that the tabernacle was not quite perpendicular to the deck, a quick investigation showed that it was about 1/16" too long on the starboard side.

A few seconds with the block plane in the vice and the problem was fixed. Like this.

I stood the tabernacle on the forward deck and set the square next to it.


More Clear Coating

The spars and other pieces which had received their first clear coat of epoxy were sanded smooth with P80 grit.

Here we are sanding outside.

The sanded spars were taken inside and laid on the empty wood racks which are now a useful work surface.

 Here they have received their second clear coat.

The drop boards got their first clear coat while the resin was flowing.

I like clear coating - you cover so much so quickly!

Tabernacle | Test Installation

The finished tabernacle was bolted in place for a test installation.

It looked great! This is it.

I'm still not convinced that four 8mm bolts are going to take the strain from the mast. I may fit it permanently when it's on the trailer.

Tabernacle & Boom Gallows | Rounding Edges

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.

Very nice!

Boom Gallows | Drilling Support Pole Holes & Test Fitting

It was time to drill holes for the stainless steel poles on which the boom gallows will one day sit.

This would be a challenge because the gallows is not flat and the holes must be drilled into a curved surface.

They must also be perfectly perpendicular and exactly the right distance apart, or the gallows will not fit onto the poles.

The first activity was to measure the exact distance between the support pole holes in the seatbacks.

The gallows pattern shows where the holes should be, but the chances of that corresponding to what I have built are virtually zero.

So I cut a couple of 25mm wood dowels to exactly the same length to substitute for the steel poles. We can't use the poles themselves - there is not enough headroom.

I hammered a tack into the end of each dowel, in the centre. Then I installed the dowels and laid a piece of straight stock across the boat on top of them, making sure that it was level.

It looked like this.

By tapping the piece of stock down onto the dowels I marked the exact distance between their centres.

Needless to say it was about 1/4" out from the pattern!

The pattern says the 25mm holes should be 60mm deep. I set up the pillar drill to practice on some scrap, and promptly found that it only has 55mm of travel.

So that was that - my holes would be 55mm deep.

Then I carefully set up the gallows on the drill table. This picture shows how it was done.

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.

I marked a line where the centre of each hole should be using the measurement obtained above, and made sure the line was perpendicular to the datum line.

I then scribed this line across the bottom face of the gallows and marked in its middle point. This would be the centre of the hole.

Then I clamped a piece of straight stock to the gallows, exactly on the datum line.

The gallows was clamped in place on the drill table with a heavy drill vice, and propped up until exactly horizontal, as measured by a spirit level resting on the datum line. As here.

Then the hole was drilled with a 25mm Forstner bit, like this.

The second hole was drilled in the same way, and test fitting made on the dowels.

It was a perfect fit!

The last task was to ream out the holes in the gallows a little to accept the stainless steel poles, like this.

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.

That was a lot of fun!

Tabernacle | Cleaning Up & Drilling Holes

When fully cured I cleaned up the tabernacle.

I had plugged the countersunk holes for the wood screws, and also three screw holes which I had drilled on the wrong edge of one side piece.

So the plugs were trimmed with a Bonsai saw and a chisel, like this.

The tabernacle was sanded clean and drain and pivot holes were drilled.

Here I am marking in a 10mm drain hole in the bottom rear edge of each side, using this marvellous Iris drawing compass which was a gift from my son. Thanks Nick!

The pivot and drain holes were drilled with the drill guide to make sure they were perpendicular, like this.

And finally here are the finished drain holes, made into slots.

That's the tabernacle done!

Boom Gallows | Marking Up & Cutting Out

I had been looking forward to making the boom gallows because it seemed like an interesting woodwork challenge.

The first task was to mark out the gallows on the balk of timber, which incidentally is not part of the hull package and is purchased separately. A pattern is provided for this.

Here it is.

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.

So my gallows is being made from a beautiful piece of Douglas Fir 1 7/8" in thickness.

The jig saw was used to cut out the gallows. In this pic it has been partially cut.

And here it is fully cut out.

Here we are shaping the curved bottom edge.

A fine saw rasp is ideal for this.

And here we are planing the curved top edge to shape.

The ends are shaped in the vice, like this.

Again, the Japanese saw rasp is ideal for this.

Finally a shallow notch is cut in the top of the gallows, to catch the mast and the boom. It looks like this.

The next step is drilling holes for the support poles, which should be fun!

Tabernacle | Gluing Up

When the bolt holes were all drilled it was time to glue the tabernacle together.

Once again it was disassembled, glued up and then screwed back together.

A 3" spacer was inserted in the front of the tabernacle to prevent the clamps from squeezing the gap. You can see the spacer in this pic.

  This tabernacle certainly is a lot of work!

Tabernacle | Drilling Bolt Holes & Test Fitting

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.

Looking good!

Tabernacle | Fitting The Backing Plate

When satisfied that the bolt holes for the tabernacle were marked in the right position I test fitted the backing plate with temporary screws.

The plate has to be secured with a single screw inside the cabin, and then four more screws from outside.

Here is the inside view.

And this is the outside.

I used plywood washers to protect the cabin wall.

When satisfied that the backing plate was fitted correctly I took it out and glued it back in place, held firmly by the temporary screws.

The final task when it had cured was to take out the screws using a heat gun to soften the epoxy to prevent them from snapping, like this.

Onwards and upwards!

Tabernacle | Marking Up Bolt Holes & Rounding Edges

The next task was to drill holes for the four 8mm bolts which will secure the tabernacle to the cabin wall.

I did this by marking in the vertical centre line inside and outside the cabin, and using that as a datum line to mark in the bolt hole locations. It looked like this.

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.

Here, for example, are the bottom two holes on the outside cabin wall, just above the fillet which joins it to the deck.

All looked well so I rounded the edges of the backing plate ready for installation, as here.

Bolt holes will be finally drilled when the backing plate is permanently in place.

Tabernacle | Making & Test Assembly

When the laminated sides had well and truly cured I cleaned them up.

The side pieces were marked out using the pattern provided and then cut and planed to shape, as here.

The bottom rear corner was rounded over to accommodate the fillet between the cabin wall and the deck, like this.

The bottom edges were trimmed carefully to size with a sharp plane and a bench hook, like this.

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 first completed side piece was stood in place on the forward deck, as a test fit. It looked pretty good!

I then made the second side piece, in the same way.

Next I marked out the rear piece of the tabernacle, again using the pattern provided.

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.

Here I am drilling the screw holes on the pillar drill, to make sure they are perpendicular.

The pieces were then carefully screwed together, like this.

This is the assembled tabernacle in the vice, with its curved rear edge being smoothed with a rasp.

The component was then test fitted in the boat, like this.

It looked like an excellent fit!

Finally, I took it to pieces and reassembled it with 8 gauge 1 1/2" bronze wood screws, like this.

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.

It turns out that 8 gauge bronze screws are not available in lengths greater than 1 3/4", so I drilled out the holes with an 8 gauge countersink bit to accept the shorter screws. This is the bit in the pillar drill.

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.

We're getting there!