Strathkanchris's Little World

C’mon Gramps – hurry up and finish it

  ’Stangarra’ is an Iain Oughtred designed Stickleback clinker ply canoe, 10′8″ long by 27.5″ beam, a lightweight open canoe for those days when a sudden whim demands going out on the nearest water. After building ‘Scotch Mist’, Iain’s MacGregor sailing canoe design, in a search for a boat that I would be able to launch into the water single handed and finding that she was just a tad too heavy, I wrote to Iain chasing a rumour that there was a smaller and lighter canoe in the offing. I also had four sheets of Robbins Super Elite marine ply left over, this had to be turned into another boat. Iain came back by return confirming that indeed he had been working in that direction but so far there was little more than the lines diagram on paper. If I was interested . . .  .  .    .    . Of course I was, the chance to be an early builder of one of Ians plans was too good to pass up. In short order Iain had completed the plans (copy inscribed No1) and it was now up to me to turn Iain’s magnificent drawings, which are a work of art in their own right, into a three dimensional floating object – and not let him down in the execution. Autumn turned into Winter and the Little Green Shed got a little uninviting for Boatbuilding then Iain published ‘The Article’, Watercraft Magazine W67,Grand Designs, stating that I was well on with the build, yes – in my dreams. With this kick up the backside and the New Year being well and truly in I gathered my resorces, put on three extra wooly pullies and set to.  Living, as one does, 65 miles from the nearest timber yard I considered the mould material, lightening struck, the moulds from the Scotch Mist build were still in the shed, since the Stickleback was smaller all round they could be cut down and recycled!

Afficiandos of Iain’s work will have realised that with four sheets of ply in hand I had enough material for another two canoes. Having done the Mac the next one down size wise was the Wee Rob. Had I had my brain in gear I could have been truly Scottish and cut the moulds down for the Wee Rob and then again for the Stickleback – real frugality. I would also have had the full set of canoes. Ah well – life is full of missed opportunities.

So to work, stage one was to mark out from Iain’s full size mould profiles each mould outline on the nearest larger Scotch Mist mould.As I use a variation on the Tom Hill method of building clinker ply, which entails the use of ribbands to define and support the planks during construction, I needed to reduce Iain’s designed profile by the thickness of the ribband. 

The moulds were erected on the Scotch Mist strong back, as this is about 14 ft long it will do for any boat up to that length. Built from L girders it will stand up to a lot of punishment and stay rigid and flat. pretty essential in this kind of work. Next was the lamination of the inner stems, these were made from 4mm thick strips of Mahogany, the less expensive West African stuff, Brazilian would have been nice but ££££ £  £. These were glued up with Balcotan polyurethane adhesive – the first time I have used it for a boat. Mainly because the shed was so frigid and my normal choice, Epoxy, would have resulted in a high electricty bill from pouring heat in to get it to cure. I was converted. Laminate in the morning and clean up the result the same afternoon, much kinder to my tools = less time on the waterstone regaining the edge and kinder to me (and my pocket).

 Inner stem goes back on the jig, a layer of brow parcel tape stuck over the mating surface inner/outer and the outer stem laminations glued up and clamped in place. I probably used too much goo but since it is so easy to clean off afterwards I reasoned that better too much than not enough. What I dreaded was unsealed cavities in the lamination which may have provided a seat for future rot to set in.

This shot shows both sets of inner and outer stems, one set fully cleaned up and the other as they came off the laminating jig. The hog and plank positions were lifted from Iain’s full size drawing before glueing the backbone (Hog and Stems) together.

The cleaned up inner stem is then used to cut a rough profile board to support the stem and ribbands during the planking process. This was simply glued in place, ribbands being fitted after the glue had set firm.

After careful fitting  of the stem it was glued to the hog, again with the Poly goo. The result cleaned up ready for permanent installation in the building fram. Once installed the hog will be trimmed to flow into the line of the stem and both will be bevelled to take the planking stock.

This shows the first Garboard being glued in place. Even with every clamp I have – and I seem to buy a few more for every boat, which is rather strange because the boats are getting smaller, perhaps a new compulsive aquisitorial disorder – there are never enough to hand. I usually find a couple buried in the detritus of the workshop after the event.

   Once the Epoxy has gone off the second Garboard can be glued in place, this is slightly trickier because the first blocks access to the clamps along the hog. I find that adequate pressure can be generated by the use of spring clips (christened Blackbirds by a neighbour when she saw them drying on the wire fence after washing the workshop dust off) with a supporting scrap of wood underneath the ribbands. The occasional bungee cord also works wonders.

Once the garboards are in place planking up moves along much more quickly, I can usually get the next level of planks cut out, trimmed and glued up during one days work. The second planks go on using all the clamps again. This shot shows the planks extended beyond the stem so that they can be temporarily secured with a few chipboard screws through the extension, once the glue has cured the screws are removed and the planks trimmed back to the stem, I learned this tip from Tim O’Connor when he was showing his Walt Simmons Lapstrake Canoe in the WaterCraft Amateur Boatbuilding Competition at Beale Park in 2006, clever man. This way I avoid any holes penetrating the planking and spoiling the look of the bright finish. My aim is to have a totally glued hull with no metal fastenings in other than those needed to attach fittings.

In the past I have had great difficulty in finding an easy way of fixing the Bilge runners as in most instructions, i.e. after the basic hull is complete. I now fix them as soon as the plank they are attached to is itself firmly in place on the building frame. This way I can still devise a clamping set up which removes the need to screw the runners to the hull. Also you don’t have to wrestle with slippery lengths of timber that will try to go anywhere except where you want. This is the third boat I have done this way and had no problems with the system. 

Having leapt ahead I realise I should have said something about making the joint between planks. This has become so simple that I am normally on autopilot doing this part of the build and had lost sight of it. Thinking back to my first clinker ply I now recall the sense of dread as I approached my first one. So perhaps a bit of explanation is called for. A lot of the strength in a clinker ply boat comes from the angled joint between the planks, because this is glued the thickness of the boatskin effectively doubles along the line of the join significantly improving the rigidity (the same effect as an epoxy fillet in S&T but a lot more attractive in appearance).The angle of the bevel changes along the length of the plank and it is important to get this right. Sounds a bit of a nightmare but following the Tom Hill technique explained in his book, Ultralight Boatbuilding, it is dead simple.

I start by marking the extent of the bevel using a simple lap gauge, an off-cut of wood rebated the depth of the lap by the thickness of the ply. Iain drawings always show the lap depth which is the same through each design. The gauge is simply run along the edge of the plank with a fine pencil held against the end scribing a light line along the plank. 

I have modified my Stanley low angle block plane to Tom Hill’s specification, by using the extension side arm resting on the ribbands the exact angle of the lap joint can be achieved very quickly – I can plane the bevel along the whole plank in less than three minutes – I probably spend more time keeping the plane blade sharp than I do actually taking wood off with it. I find that having the plane body at an angle to the line of cut helps to give a really clean cut and avoids tear out in the ply, which can be a problem in the cheaper grades.

Having produced a near perfect winding bevel there just remains the task of cutting the gains to allow the planks to lie flush with each other at the stems. I do this using a Japanese saw, incredibly sharp and able to produce highly accurate cuts in even this rank amateur’s hands. simply make a gradient cut so that the blade is kissing the surface of the ply about five inches in and goes almost full depth by the stem. Having defined the edge of the gain use a very sharp chisel to remove the waste.

The dreaded scarf joint

For Stangarra I have done all the scarfing on the mould and found that I have had far better results. The two halves of the planks are spiled allowing spare in the join area to give enough over for the scarf joint. It has been far easier to get a reasonable alignment of the grain pattern at the join doing it this way as well which has benefits in the look of the finished boat. I use a small lowangle block plane to cut the scarf, kept really sharp, this avoids tearout and gives a near invisible joint once glued up.

A pair of parcel tape covered blocks are clamped each side of the joint making sure that the feather edge is covered and pressured.

 This shot also shows quite well the use of offcuts of wood to bridge the ribbands to allow clamping of the plank overlap along the lands while the glue cures.

In situ scarf clamped up - from the outside

The planking continues until, sooner than you thought possible, the last plank is clamped in place and you have what looks like an almost finished boat. Truth is, for an open canoe, you are about half way through the exercise. Worth stepping back and giving yourself a pat on the back.

Final plank in place

Basic Hull completed and cleaned up ready for Keel and outer stems

  

right way up at last

 Once the hull is the right way up a start can be made on cleaning all the surplus glue from the interior joints. I use a hot air gun to apply gentle heat (too hot and the epoxy will come unstuck!) with an assortment of home made scrapers. Once the epoxy has been softened by the heat it comes away quite easily leaving a very clean result. I find it less trouble to remove the surplus glue this way rather than trying to get under the hull during planking to clean up whilst the glue is still liquid (I don’t fold as easily now as when I was young) Machining the gunwale rebate On my Humble Bee build the gunwales were glued to the Shearstrake leaving the edge of the ply showing. The appearance of this has always niggled me slightly so I made the Gunwale strip thicker than specified by the thickness of the ply and rebated it by 4mm leaving a 4mm lip to cover the edge of the ply. Not having thought of this when I was planking up means that the hull is now 4mm deeper than Iain’s plan. Still given my excess of weight that is probably no bad thing. After rebating the Outwale strip was trimmed to length so as to fit snugly against the stem and glued in place. Once the glue had cured any surplus was cleaned off and the outwale gently made flush with the sheerstrake. Thwarts laminated up from 6mm strips of Ash.

Laminating Thwarts

 To make absolutely certain that I got the thwart positions right I laminated and fitted the thwarts before installing the gunwale spacer blocks.  Strips of Ash 6mmx50mm were cut and laminated over wooden blocks on the end of the building strongback. Once the glue had set the edges were cleaned back square and the profile marked out and cut on the bandsaw. The end bevel was marked and cut and the finished thwart tried for size. Satisfied that they were where they should be longer spacer blocks were cut and glued in place, aligned with the centerline of the Thwarts.   

Breasthooks roughed out

Next the breasthooks were roughed out, as the available Ash was not quite large enough to cover the full width I made a feature by placing a slightly tapered offcutt of mahogany on the centerline, the narrowest part being the same width as the inner stem so that the dark wood flowed right into the stem once assembled. 

The breasthooks were beveled and trimmed to fit the angle at the stem, once satisfied I took a circular sander and attacked the top surface to form the slight curve that adds so much to the look of the boat. The breasthooks were then glued in place after cutting the rebate to accept the inwales. The curve on the inside of the breasthook was formed with the help of a 50mm flap sander in my electric drill. This should have been done after glueing the inwales in place – I didnt leave enough wood to for a really good transition to the inwale angle as it moves into the breasthook, thus we learn.

Spacer blocks were cut  at 45mm length and after some brain numbing calculations (not one of my stronger talents) I cut three different length blocks to space out the spacer blocks, the length of the gap needed was slightly different between bow, forward thwart, back thwart and stern. The spacer blocks were glued and clamped trying to keep the top alignment as close as possible to the outwale. Once the glue had cured any surplus was cleaned off, once the inwale was in place is was going to be difficult to get at these joints again for sanding.

Installing the floors

 With the breasthooks and spacer blocks glued in place it was relatively straightforward installing the inwales, Balcotan again and lots of clamps, minimising the amount of glue to reduce clean up. Much easier with the polyureathane glue than epoxy but still very fiddly between the ‘wales. Almost there! Iain’s plan specified a sheet of ply as the ‘floor/seat’. Experience paddling ‘Scotch Mist’ had shown me just how much water I manage to bring inboard as paddle drip. As I have a strong aversion sitting in a puddle of water I wanted a seating arrangement that allowed any surplus water to slosh around harmlesly below my nether regions. I followed the arrangement in ‘Scotch Mist’ by putting in floors and floorboards, this has increased the weight slightly but to my mind looks more ‘traditional’ as well as improving my comfort. 

Buoyancy lashing eyes

As this build was the open version I have concerns about what happens when she gets swamped, buoyancy bags were going to be a must have. I have seen how easily apparently well restrained buoyancy can escape in surf so I needed to devise a way of securing them. After a bit of research I found that canoe buoyancy bags come around 32″ long, that determined where my lashing points needed to be. I made small triangles of mahogany with a 10mm hole bored through (I lined the hole with an insert from copper microbore heating pipe, just cut to length and squeezed in place with a C clamp) which were the epoxied in place with the help of masking tape – a couple still managed to stray from the vertical. A combination of cross lacing through the gunwales and these lashing points should hold the bags in place.

That pretty well finished all the woodwork part of the build, there just remained putting a good finish on her. I start by soaking the whole boat in a scandanavian product called ‘Varnol’ .

The completed boat, Varnol soaked and ready for Varnish.

This is put on wet on wet at about a 50% dilution with gum turpentine. It soaks well into the wood and gives a good base protection. Used as a primer sealer under varnish it seems to give really good adhesion to the varnish. Certainly my boats finished this way have shown no signs of varnish failure, the oldest is now 5 years since first varnishing and they live outdoors most of the year with all that the climate of NW Scotland can throw at them. Once the varnol has soaked in as much as it’s going to I rag off the surplus with a Turps dampened rag which improves the look no end, all the runs and dribbles just vanish.

The Varnol is allowed to dry off, very weather dependant – when I did ‘Scotch Mist’ it was deep mid winter, which up here means cold and dank, and she took over two months to dry. Stangarra, being done in a very good summer dried in about 24 hours, warm and breezy is what is needed. The Varnishing can then be started, In my view, having invested a fair amount of capital and a lot of time in the boat so far, anything less than the best is a false economy. My varnish of choice is International ‘Schooner’, I know how it reacts for me and since it produces the result I want I am reluctant to try anything else. I have seen good results from Epifanes but have not tried it myself, I did read on an American Wooden boat forum that it has a tendancy to craze after time and this rather put me off. I usually put three coats on within the open coat time to give a solid base for my lettering. The second coat is given a gentle rub down with 400 grit paper, either dry or wetted with water depending on personal choice. I prefer dry sanding at this stage as I find it less aggressive – I can see no point in sanding off most of what you have just laboured putting on. Just get rid of any runs and dribbles, I don’t know if the experts get them but I certainly do!

I think that a good wood with a nice glossy varnish to bring out its best really calls for proper Gold Leaf signing. A good guilding guide was in Watercraft Magazine (no 31, Jan/Feb 02), a superb article by Mike Hanyi. It taught me all I know on the subject. I tried it out on my first Humble Bee and found signing on the boat quite hard on my feeble back muscles.

Home made waterslide transfer, part made

 For Scotch Mist I tried making my own waterslide transfers, the technique seemed to work quite well and it was certainly much more comfortable lettering at a table in good light, the same method was used for Stangarra, I also tried using Iain’s drawing of a Stickleback from the plans as an insignia for the bow. I am still unsure about the wisdom of this – I shall see if it grows on me and may yet sand it off. I might do a write up on how I make my transfers if interest is shown.

The transfers are applied to the boat, trying to get both sides to match – another reason why I may sand off the fish, basic incompetance in handling a tape measure means mine don’t.

A minimum of three coats of varnish are applied over the transfer before going anywhere near it with sand paper. once those three are dry and hard then a gentle sanding with W&D 400 grit used wet starts to get the surface towards the flatness needed for a good gloss. It just remains to varnish and rub down for another four coats. There will then be 10 coats on and enough protection for even quite rough use.

Name and 'Fish' in place

 That just about brings the story up to date, the last few coats of varnish are being applied ready for her maiden voyage at the UK-HBBR Rally  at the Cotswold Water Park on the 6th & 7th September 2008. If you are interested in seeing her in the flesh, so to speak, then feel free to come along to the Rally, we welcome all interested in homeboatbuilding, whether or not they have a boat currently.

 

6th September 2008 – She floats.

Launching took place yesterday on a grey mizzley day with no ceremony. Quite a few of the HBBR members had a go and all seemed to enjoy the experience. Intital thoughts are that the shrinks even more than usual when placed in the water. Not a boat for choppy waters – the freeboard with largish blokes aboard is about 3.5 inches – which doesn’t feel very great. She is a bit twitchy but once you get used to her a very secure feeling boat. After the first couple of minutes I forgot about inadvertant swimming and just had fun. She gives more fun per foot than any other boat I have played with. Nice.

 

Launch day - maiden voyage - 4

 

Launch day - maiden voyage - 1

 

Launch day - maiden voyage - 3

Launch day - maiden voyage - 2