Construction - part eight

Mike Griffiths (guest blogger) bends it like Beckham

Balls, you ask? No canoe planks! With the last set of planks stitched in, it was time to (I quote the book) “pull the planks together at bow and stern”. The book further suggests that this could be a fight and that a spring clamp or two might be needed to position things. A few practice flexes of the hull halves suggested that all this was true – and then some. Plus I should point out that the ends of the copper ties are sharp – this adds some pain and the odd shallow but painful gash to the process.

Inside and outside shots before stitching bow and stern

Slacking off the first three ties along the keel helped the first two planks to flex enough to allow me to start drawing the bow and stern together – but (of course) I need these ties in place to help get the bottom two planks to twist into shape. Note – spring clips immediately slide off stressed planks and fly across the room with a “ping” sound. Did I mention that the ends of copper wires are sharp? Oh yes I did – and they are. If you decide to build a stitch and glue canoe, recruit an assistant for this stage – and get someone with strong hands who is reasonably impervious to pain. You can do it by yourself though – I can't even begin to describe how – but you can. Working slowly from the keel line and allowing the wood to rest at a couple of stages seemed to work. Whoopee! I have something that looks quite like a canoe – well ish. The stem and stern were a bit wobbly and the overall shape was a little bit odd but it was a good start.

Placing a spreader stick measured to just short of the canoe's designed beam at the centre line helped with the overall shape but it then needed some adjustment with a mallet to bring each pair of planks properly into line and to fair the stems overall – well in one dimension. The other dimension needed a couple of lengths of wood screwed and clamped to the canoe to bring them exactly into line. One thing you learn is that even dimensionally matched pairs of planks do not bend equally without some encouragement – the minor differences in the internal plies in the board affect the rate of (and resistance to) bending. The “gains” are a weak point as well and do not help bring the ends of the boat naturally into line.

The continued sub-zero day time temperatures and a couple of days of snow falls meant that I ended up lofting the lines of the bulkheads and decks on the kitchen table. Sawing them out had to be done outside in the big barn but the physical effort generated some heat to counteract the cold. The Japanese style pull saw came into it's own here and the resulting pieces needed almost no finishing. I am really getting into this tool – it is just about the saw of choice now for close and accurate work.

Ready to start tightening all of those wires.

The good book says that fitting the bulkheads is “one of the hardest chores in boat building”. Amen to that. The holy writ also suggests that the bulkheads could move an inch or two either way to get a good fit. In my youth I spent me leisure hours with a fun group where most of the guys worked in the (then still vibrant) Chatham dockyards. We had a little mantra that went something like this:

“An electrician works to the neatest quarter of an inch. A joiner to the nearest sixteenth. A millwright to the nearest thousandth and a shipwright to the nearest ship.”

I have probably missed one or two trades but you get the drift I am sure. I suspect that the canoe project has just shifted from the domain of the joiner to the domain of the shipwright.

Next weekend seems to be dominated by some sort of winter solstice celebration – named after some chap called Noel. There was a hint that I was not supposed to spend most of my free time outside boat building so there might be a short gap before I report on the process of gluing the hull.

Construction - part seven

Mike Griffiths (guest blogger) is routed and then stitched up.

My canoe construction project had got to the point where I was gluing the half planks together to form the full length strakes used to construct the canoe body.

These two planks being glued side by side give a better view of the curvature that needs to be accurately maintained right through the joint

All of the planks were glued before the weekend and I was looking forward to cutting the rebates in the bottom edges to manage the overlaps that create the lapstrake effect. Both days were cold – the thermometer showed 2C and there was a strong North Easterly wind – no idea what the temperature was taking the chill factor into account but it was most unpleasant in our big barn where my workbench was set up ready to start work. The doors needless to say faced North and I needed them open for the light. Still – this was my opportunity to advance the project, so with gritted teeth...

It might seem odd for me to say that it was a bad thing that my first run with a router along a piece of test plywood went well. In fact it went swimmingly – like a hot knife through butter and with a perfect 9mm wide rebate just 1.5mm deep. So that made that decision – the router it was for this job even if this was the first time I had used it. The reason why the test run was not great was that the first real plank I rebated fought tooth and nail. I was not ready for the variability in the grain of the plywood layers as I advanced down the plank. I learned though and learned how to deal with the feedback from the router. Like everything else this was skill to be acquired.

I also had to cut the “gains” at the end of each rebate – allowing the planks to be drawn together at the two stems. I found that a combination of a small rebate plane and a sanding block was best for this final step in the shaping of the planks.

I had to drill 1.5mm holes every six inches along every edge of the bottom planks and along the top edges of plank sets two to four. I used the little jig advised by the book to assist in placing the holes accurately and drilled through each pair of planks together.

My simple drilling jig and the routed rebate along on plank.

The next step was to start stitching the planks together – but first I needed at least 300 short pieces of copper wire. I could not locate bare copper wire anywhere in my locality so set about stripping the plastic insulation off metre after metre of 1.5mm electrical wire. My younger daughter helped in clipping the lengths to around 10cm while I risked injury stripping the plastic coating using a Stanley knife. She watched “X Factor” while she clipped and I watched my thumb.

The weather forecast for the next week showed temperatures dipping below (and staying below) zero. This persuaded me that I would have to manage the next phase of the canoe construction in my office – which I could heat enough to keep from shivering too violently – and even warm up to a comfortable level when I next need to apply some epoxy resin. Of course, that makes lofting the bulkheads and decks problematic – perhaps I can borrow the kitchen table for that task – well maybe.

I extended the width of the two metal trestles I had to a tad more than the planned width of the canoe by drilling through the top bars and screwing some softwood to the top edge. I set these up and draped the first two planks (those that will form the bottom of the canoe) over them. I say draped because all five pairs of planks were very flexible and difficult to handle even allowing for my caution when moving them - I wanted to avoid (even more) accidental damage that might be difficult to repair.

I used the copper wire to stitch the two bottom planks together along the keel line. I then opened out the two planks and flexed them a little to get the two edges to butt together. I then fetched the next two planks to stitch to the first two. Offering them up got me very worried as the next two planks seemed too long. I hastily re-checked the lengths of both plank sets against the plan offsets – but they appeared to be in order. Even allowing for the fact that the next two planks were going to have to follow the curved edge of the bottom plank I could not see how I would not end up with too much plank at one end of the canoe. I re-read my bible (“The Canoe Shop” by Chris Kulczycki) – and there was a hint that this inequality would be evident at this stage. Also on close inspection, one of the pictures in the book showed an overlap between the first and second planks during the stitching process. Relieved? Well a bit – I decided to reserve judgement.

Once I had got part way through stitching the first of these planks to the bottom pair I felt the project change. The planks started to stiffen up as they took on the curves and the whole thing began to feel like it might become a boat. It might sound silly to say it but the canoe was starting to take on a life of its own.

A number 3 plank waiting to be stitched into the canoe.

Stitching on a plank involved drilling a hole just above the rebate opposite each of the pre-drilled holes in the adjoining plank. With a little twist the 1.5mm copper wire passed through the 1.5mm hole. I could then use some long nosed pliers to pull the wire through and to apply an initial twist or two to complete each stitch. I pressed a small piece of plywood to the back of the plank where I was drilling the holes to minimise any damage to the outer ply as the drill broke through – added the possibility of drilling into my fingers I suppose but (so far) no spectacular blood letting.

Construction - part six

Mike Griffiths (guest blogger) gets stuck into gluing.

I left off my tale of building a lapstrake canoe at the point where the scarf joints needed to turn the half planks into full length planks had been cut. Now all I needed to do was glue those joints. This was another scary stage as the planks are all curved and that curve needs to run smoothly and regularly through the glued joint. The canoe plans provided offsets from a line drawn between the end of the planks and the edge of the plank at the point where the joint should be made. However ensuring that the planks actually end up being glued in that position looked problematical at first.

The first thing I did was to buy three sheets of cheap composite board that looks like it is made from wood shavings. The ones I ended up with were narrow but had tongues and grooves along their edges making it simple to join them into a continuous strip. I nailed the joints to hold the sheets in register as I wanted to be able to draw a continuous line down their length. I was not going to rely upon this line but it helped get the planks roughly in position – I then re-checked that positioning using a line of string. I placed the first pair of half planks from one of the sets into position with the scarfs carefully overlapped and (after double checking all of the measurements) then drove pins into the board tightly alongside the ends and in a couple of positions along the top edge of each plank. This gave me a jig for setting up the second plank. After checking that the fit still worked for the second plank I mixed up a batch of epoxy resin – my first.

Mixing the resin was a new experience but the resin pumps supplied along with the West resin and hardener ensured that the mix was correctly proportioned. I had to thicken the mix using some colloidal silica – another first that needed some experimentation to get the thickness right. The book said to make the mix the same consistence as “jam” but I have met a lot of different jams in my time. In the end I went with apricot conserve.

I applied the epoxy to both surfaces of the joints of both planks. The planks were set in position within my mini jig with pieces of polythene sheet under and between the sheets. The joints were clamped using a short section of timber screwed into the boarding just outside the edges of the plank joints again separated with a strip of polythene.

With plenty of epoxy left over I then glued up two of the oak lengths destined to form inwales or outwales. These I clamped using plastic spring clamps as these would not stick to the epoxy and clearly had sufficient clamping strength to hold the scarf joint tightly closed. Three clamps per joint seemed optimal.

I had pre-heated the gluing area to about 16C (roughly 60F in old money) and ensured that the epoxy and hardener were also warmed through so they flowed properly – it was a bit chillier outside so a small fan heater did the trick. Now all I had to do was wait for the epoxy to cure.

The first canoe plank clamped in my gluing jig plus two oak lengths made from three 2 metre lengths clamped and curing.

Next come the other four plank sets and two more oak lengths. I also have to play around with the router to determine if I should use that or a rebate plane to cut the plank rebates – but that is getting ahead of myself.

Construction - part five

Mike Griffiths (guest blogger) continues his canoe construction story with plane tales.

I finished off sawing out the remaining sets of planks rather more quickly than the first couple of sets. By the time I had cut the fifth set I was reasonably happy that I was on top of the task. I was feeling so happy with progress that i went back and re-lofted and then re-cut one of the sets that I rather felt I had made a “pigs ear” of (now that's a phrase I have not heard in a long time - appropriate though).

With five plank sets now sawn out I had next to plane them to their lines. Planing a curved line seems just a bit disingenuous before you start and planing the inside of a curve even more so. However with a sharp block plane it can be done quite quickly. This was my final chance to ensure that my curves were fair (the canoe's you understand and not any personal love handles) and that the cut lines were square – giving me four half planks from each set that were as near as possible identical. By the time I had completed the last set I was really getting a feel for the tool. I suspect that a constant feature of this project will be the feeling that I am just achieving some measure of competence as I complete each phase. Is this why Paul described boat building as addictive? Not so much an addition perhaps but a desire to see what you can do starting out with better honed skills.

I now had to cut the scarf joints to make each pair of half planks a single full length plank. The scarfs should form a 1 in 8 ramp for optimal strength so, as each sheet of plywood is six millimetres thick, the ramps should be about forty eight millimetres long. The plans made provision for a one inch overlap on each half plank so I went for a five centimetre ramp – just about two inches long. Most builders cut their scarfs with a block plane but after a practice run on the discarded plank set I decided to try using a belt sander.

It is best to cut all four ramps for a plank set together as the staircase formed by aligning one plank end with the start of the ramp for the next automatically gives you the correct cutting angle. How cool is that?

Nearly half way through cutting one set of scarf joints. Just a bit wobbly but that can be corrected

Just checking that a finished scarf ramp is level

I made up a simple jig to help me cut the scarf joints on the oak lengths that will make up the inwales and outwales. This allowed me to quickly and accurately cut the 16 joints required in around 10 minutes (perhaps 20 if you want to include making the jig) – a lot less work than planing them or even using the belt sander. Now can anyone thing of a use for all those oak wedges?

Scarf jig for the table saw – the same 1 in 8 ramp as for the plywood planks.

Construction - part four

Mike Griffiths (guest blogger) gets to grips with his saw.

Cutting out the planks

This is the stage in canoe construction where you turn four sheets of expensive marine plywood into 20 well formed half planks of a canoe or, perhaps, just a small pile of sawdust and a stack of “off-cuts”. So much depends upon the accuracy of the preceding lofting process as well as the 'saw action'.

The half planks are cut from four sheets of marine ply sandwiched together. The idea is to ensure that both ends of the canoe are identical and (more importantly) that both sides of the canoe are identical. The alternative would be to end up with a canoe that did not fit together or only paddled in circles. It is important to ensure that the four sheets stay “in register” while each half plank set is cut out. The best approach is to nail or screw the sheets together at various points between the marked out planks – avoiding the cutting lines and larger waste areas that might come in useful at some later date.
Then, as each plank is cut from the sheet, the section hanging over the edge of the working surface can be clamped to keep everything tightly controlled as it is cut away.

My plan was to cut the planks out by hand. I had modified a Stanley 1-15-215 floorboard saw by grinding off the teeth on the upper/front curved face of the blade to stop these wider teeth jamming in the kerf when I was sawing at a low angle through the boards. I had also been reading that many expert woodworkers favour a Japanese ‘pull’ saw (in particular a ‘ryoba noko giri’) as they cut on the pull rather than push stroke and this allows the blade to be very thin with a very narrow kerf – ideal for this sort of project. Quality Japanese woodworking tools might be expensive but Irwin do a very reasonably priced version with two cutting edges. So a “head to head” between these two saws was in the offing.

Irwin version of ‘ryoba nook giri’ pull saw and the less exotic Stanley floorboard saw – prior to my modification

I elected to screw the four sheets of plywood together at intervals along the waste areas. I decided that screws would be easier than nails  to remove if they proved to be in the way. After one last look to check that my plank outlines matched the curves and lines of the sketch in the book I set to.

The Stanley saw was first up. I am a frequent enough saw user to have some confidence in what I am doing and this saw was spot on for accuracy – it followed the plank curves well and effortlessly held a pretty constant distance of less than a millimetre from the pencil lines. The snag was that progress was slow. At 13 teeth to the inch (now there is a non-metric standard measure) I suppose I should have expected this but progress was frustrating.

The Irwin “pull” saw made much faster progress – but – you knew there was a but – this was my first attempt to work with this new style of saw. I found it difficult to keep my saw cut close enough to the lines on a long cut – thus increasing the amount of work required to complete the cutting and shaping of each set of planks. Having said that, the advantages of this style of saw were becoming apparent – I just needed more practice. I suspect that I am going to become a frequent user of this saw and I can’t wait to use it on some jobs where it’s fine cut is going to be a real benefit.

So which saw is the best for this task then? Remember that I am cutting roughly twenty five linear metres through 2.4 centimetres of African mahogany. The winner is – “save up and buy a decent jig saw!”.

No seriously, (homespun philosophy moment) – once you have achieved proficiency with a hand tool then you will find the equivalent power tool finished the job faster – but no more easily. Power tools are not always better. This is just a longish job that is worth taking time over. I had far more fun ripping a couple of oak planks on the table saw to extract some lengths 2.5 centimetres wide to scarf together to form the inwales and outwales of the canoe. Given that I ended up buying two metre planks then I will have to cut 16 scarf joints to achieve the (roughly) five linear metres required – so one of the next tasks will be to make a simple jig to cut the scarfs as the time will be repaid in accuracy and efficiency.

Why were my planks only two metres long when this part of France is virtually a continuous oak forest? Well, most consumers of oak timber are artisan carpenters. They all have planer/thicknesers and band saws and can buy the pretty crude pieces of timber available from the saw mills. I could have easily purchased a slice through a tree trunk but would have had extreme difficulty in getting the required lengths out of that. So it was buy what was available at the DIY level or involve a local artisan to prepare the lengths of oak for me.

More from me when I have finished sawing – which might be a while as a combination of family commitments and entertaining look like “taking out” the coming weekend one way and another.