Outer Parts of Keel Fitted

I wanted to fit the outer parts of the keel or skeg while the centre of the boat is still easily accessible. Even with only two planks on it is a bit of a stretch to work on the centreboard case. There are two big pieces of timber involved and both have to be shaped to fit the curve of the hull. Here are photos of them fitted, glued and screwed in place.

Above is the forward section. It was shaped to suit the curve of the hull by trial and error and this was a slow process. The vertical piece of timber is wedged against the shed roof to hold things in place while I put the screws in from underneath. At the forward end (left of photo) the step is one half of the joint for the outer stem.

This is rear section or skeg. Same approach with the timber wedged against the roof. When shaping this piece to fit I made a template from scrap ply to fit the curve of the hull and then cut the timber using the template. This reduced the trial and error fitting of a big lump of timber and was much easier.

This last photo shows the butt joint between the skeg and centreboard case (both ends of the centreboard case have similar joints. There are 2 pieces of 12mm thick ply to be fitted either side of the centreboard case and I will extend these about 150mm past the butt joints to cover and reinforce the joint. The sides of the centreboard case are lower than the top of the skeg to allow a hardwood cover strip to be glued over the edges of the ply case sides and doublers. Once this cover strip is in place the whole length of the keel will be a continuous smooth line.

Second Pair of Planks

I had to glue the second pair of planks on in to stages, one plank yesterday and the other today. This is because I don't like putting screws through the planks at the stem, it makes holes that need to be filled when the screws are removed. So I use blocks with a V shaped notch and clamps - there are 2 in the bow photos below. There is a lot of twist in these planks and they are difficult to pull into place individually. Pulling them both in together, fitting the notched blocks and clamps would need 2 people. On the next planks I will try clamping "handles" to the edge of the plank and pulling them together with a Spanish windlass. If it works I'll post a photo.

There are a lot of homemade wooden clamps in use below, about 30! As I said in an earlier post, they work well and are cheap and can easily be modified to suit different situations.

Here is the stern end of the plank, not so much twist here and the end is held down on the transom with a couple of long screw clamps. These clamps are a bit precarious but provide enough pressure to hold the joint together - just don't bump them or they will fall off!

Here is yesterday's plank.

Before fitting the next planks I am going to shape the outer parts of the keel and fix them in place. This will be easier to do now while I can get closer to the centre of the boat.

First Pair of Planks

This afternoon I glued the garboard planks in place and am writing this with a celebratory beer in my hand! I knew I would have to do some final trimming of the bevel on the stem to get the planks to fit correctly. I didn't realise how much timber I would have to remove. I shaped the bevel using a long flexible batten. This worked OK for the batten but the 9mm thick planks didn't want to follow the same lines due to the considerable amount of twist they have to take. As the planking progresses the twist is less and my original bevel will be a better fit.

Here are a couple of photos of the planks and clamps in place. Screw clamps and glue blocks on the stem with wooden clamps and wedges along the keelson. These wooden clamps work well, easy to make from scrap ply and the wedges allow for a variable amount of pressure.

The glue running down the stem and across the planks at the transom is more than the normal squeezeout. I mixed up some unthickened epoxy and poured it in to gap between the two planks and around the centreboard case to try to make sure that any space left along the joint would be full of epoxy. Messy but I think it will work.

Starting the Planking Process

It's been two weeks since the last post and there isn't much obvious progress. However, I did go sailing for a week in my John Welsford Navigator and had a great time. I have also bevelled the transom, keelson and stem in readiness for the planks to go on - no pics of this as the changes are not obvious and photos of a big pile of wood shavings are not interesting. I bought the plywood for the planks, 9 sheets of marine grade 9mm Gaboon ply. Also 5 sheets of 4mm construction grade ply to make patterns for the planks. Interestingly, the 5 sheets of construction grade ply cost less than a single sheet of the 9mm marine ply!

The planks are over 5 metres long so I had to scarph joint the 2.4 metre sheets to get the necessary length. Here are some photos of the process. First, 4 sheets are arranged across the end of the bench in a staircase formation with each "tread" being 72mm wide. This provides an overlap in the joint of 8 times the thickness of the ply.

The steps are now planed away to create a continuous slope. As this progresses the glue lines in the ply give a good indication of how even the slope is. The planes need to be sharp and resharpened during the job but it is still hard work!

The sloping surfaces are painted with unthickened epoxy and left for 15 minutes or so to allow the epoxy to soak into the end grain of the ply. Thickened epoxy is applied to 2 of the 4 slopes and the joints positioned carefully so that the ply surfaces are level and the long edge is straight. I tack each pair of sheets together with a couple of staples to stop them slipping apart and then clamp the joints with 2 heavy cauls. One of the cauls is straight, the other has a slight crown on it (about 3mm higher in the middle) to counteract the tendency for the cauls to bend when clamped at the ends.

With one joint made the sheets are now almost 4.8 metres long and the scraphing process was repeated to add another 450mm to one end. The sheets are now 5.25 metres long and are filling the space in my shed quite effectively!.

While the scarph joints were setting I made a pattern for the first (garboard) plank using the cheap 4mm ply. This is pretty straightforward. I butt join the sheets of ply to get the length and then cut off a strip wider than the plank. This strip is then laid over the building frame and held in place with a few temporary nails. The edges of the plank are marked on the pattern strip from the moulds. The pattern is taken off and the marks are joined up using a long batten to get a fair curve through the points. Cut and trimmed to the line with a handplane the pattern is returned to the moulds and checked for fit.

Once the pattern is correct it is laid over 2 sheets of the marine ply a a line drawn around it. The planks are then cut with a jigsaw and cleaned up with a handplane. Here is the pair of finished planks.

The planks are laid on the moulds and held with clamps. Inevitably, some fine tuning is required but this can be done with a hand plane. Here are the planks at the bow of the boat. There is considerable twist required to get them into place and I'm doing this with shaped blocks and, while the glue dries, a few temporary screws will be used.

At the stern the planks will be easier to fix but some fine tuning is requireed here as well. The stripes on the edge of the transom are pieces of ply that I had to add to correct an error made while bevelling the transom. The bevel was perfect but I forgot to allow for the fact that the planks overlap and need the transom to be stepped to accomodate the overlap.

Last comment at this stage; this is my second glued lapstrake or clinker ply boat and the first pair of planks are the most difficult to fit. The process for the remaining planks is the same but they don't but together along the centreline of the boat and there isn't as much twist to deal with at the bow.

Three Joints

In the last week I have made and glued three joints. Doesn't sound much but two of them were quite tricky and one of those two was big! Starting with the one of middle difficulty, the joint between the transom and the keelson. First step was to make the triangular brace and screw and glue it to the transom. Once this was done the lower half of the keelson (it's in two 15  mm thick pieces) was glued to the brace and held with temporary screws.

 At the other end of the boat the first half of the keelson was glued and clamped to the inner stem. Once the epoxy in these two joints had set enough to hold the pieces together I applied glue to the two pieces of the keelson and put the second half in place with screws either end and clamps all along the length. Here's a photo of the stem end of things.

In the middle is the centreboard case which has to be glued into a slot cut in the keelson. The keelson is reinforced along this section by doublers to either side of it. These doubles are, like the keelson, laminated from two 15 mm thick strips. These were glued to gether and glued in place in one sticky operation, sticky for me that is. Epoxy everywhere!

Next step was to cut the slot in the keelson with a jig saw. This needed a bit of fine tuning with plane and chisel to get the case to fit. Once the slot was OK I opened out the sides about 2mm at the top to make it slightly funnel shaped, reason later.

With the board in place two plywood reinforcing pieces were glued either side to the case and to the keelson. These can be seen on the left of the photo either side of the mould. I mixed up a batch of stiff thickened epoxy and ran a small fillet around the underside of the joint between the keelson and centreboard case. This effectively sealed the bottom of the gap between the case and sides of the slot in the keelson. Once this thickened epoxy had begun to set I mixed more epoxy and poured it into the funnel shaped space from the top adding more as it settled until the joint was full.

While waitimg for all the above glue joints to set I sorted through the timber I had on hand for the masts and spars. These are all Oregon (Douglas Fir). I had toyed with the idea of making these hollow using the "birdsmouth" technique (Google "birdsmouth masts") but in the end I chickened out! They will all be solid, laminated from two strips of timber so that the opposing grain patterns resist and tendency for the wood to bend. Unfortunately I didn't have enough of the nice Oregon that I bought in a bundle from a deceased estate and will have to find a source of timber for the mizzen mast. I will work on the spars whenever there is spare time waiting while epoxy goes off.

I have built a rack against the outside of my boatbuilding shed (under an existing lean to roof) to store the spars and other timber.