An adventure in Clinker Ply Boatbuilding
Being an attempt to short circuit the learning process by means of Q&A between two UK-HBBR members at opposite ends of the country. The project is one of Paul Fishers sailing canoes, the Woodland 15 .
Woodland 15 sailing canoe
The two members concerned both have a few boats under their belts, Southernman (S) has built in the more common Stitch and Tape method but has repeatedly been advised that clinker ply, (lapstrake ply in our former colony across the Atlantic) is far easier and less messy by Northernman (N) who has so far built four by this method, his aversion to S&T is based on experience having built two boats by that method in his early days, being a bone idle sort he finds it all too much like hard work.
This document will consist of Questions put by S to N as problems occur. Please feel free to comment (using the box below) if you disagree or have an alternative solution. N certainly would not claim to be knowledgable on the subject, responses will be based on his experiences – good and bad – in building boats at home. Most illustrations will be as thumbnails to help the page load in a reasonable time for those with dial up. Clicking on the image will bring an enlarged version to your screen.
Paul Fisher said 3×1 screwed into a T beam would work well, ideally with old dry wood that had finished all its twisting.
I don’t have anything like that so the best I can do is get 3×1 planed which has been stored indoors at the local builders merchant, using the straightest I can find. Any comments?
Having said that it will have to be stored outside on the grass under a poly cover…..unless I build an extension to our 12ft conservatory. Or I might build a rainproof cover along one side of our house and the fence. It would be about 5 feet wide.
Thinking a bit more the strong back might have to be moved. I know that’s not ideal but I can think of ways of realigning it – string through holes in each stage or a laser level.
Umm, yes quite a challenge you have got there. I, personally don’t like the T strongback – I just think there are so many ways that it can twist out of shape. Modern timber is such diabolical quality that I would be very loathe to follow Paul’s recommendation. All my canoes have been built on a ladder type strongback built out of L girders for lightness and great strength and stability. I think the T strongback comes from across the pond where it is universal for the Cedar/ canvas canoe build and I don’t think the need for absolute level is so important – largely because the planks at bow and stern are not finally brought in permanent alignment until the boat is off the moulds so there is scope for fudging.
Once you have got the backbone (hog and stems) securely fixed the ladder frame becomes quite rigid, triangulation I expect. I did put legs on wheels at one end of the frame with the other clamped in one of those £10 workbenches so that I could move the thing around – even with 12′ width in the workshop there were still times when ……
The advantage of the L girders is that you can use 5×1/2 floorboard stock and join lengths with a butt strap to extend it. the short leg of the L is something like 2×1 screwed and glued inside the top of the side plank. Not sure if I make sense – attached some snaps to hopefully clarify.
L Girder frame upside down showing simple construction.
L Girder frame right way up showing cantelievered supports
The plans arrived today, 4 sheets including one for stitch and ply shapes. She has very nice lines and 4m2 of high aspect Bermuden sail will be fun – I remember in my windsurfing days that 4.8m2 could knock me off my feet in a strong gust! Northernman’s girder pictures are worth a thousand words, thank you. It suddenly dawned on me that the only place big enough to build her right now is the living room, pause for reader’s laughter……. Other options include:
Dining room, if I remove door from understairs cupboard. Not sure if the exit strategy is fool-proof, opening windows is the only option!
Temporarily extend 9ftx9ft shed onto patio by 8ft at the door end using 8×4 ply sheets on 2×2 frame, widen the door frame because the 36″ beam won’t fit. When the hill is complete remove the extension and fit a wider door.
But a better option is a permanent roof over the patio, using conservatory roof panels. So can Varnol protect a pine frame throughout the year?
Answering backwards, Provided you dilute the varnol with gum turpentine at 50% and soak it wet on wet till it won’t take any more (stand your pine on end in the dilute mix for half an hour each end) the pine will last a good deal more than a year. If you want permanent protection put a couple of coats on at full strength after the wet on wet soak. If you drill to fix the roof panels put a few drips into the screw holes before tightening up.
Extending the garden shed. 9′ width is a bit tight, you will need the building frame on large castors so you can slide it sideways. Big problem is going to be getting far enough away to check fairness of planks. I would use OSB rather than ply, you can get it with a pitch coating for weather proofness. Better option is to replace the door end of the shed with an open frame ’til finished. Move the door end to the end of the extended shed whilst you are building? If the boat is in the widened door how are you going to get in and out? Even with your stick like figure it’s not going to be easy. Do not underestimate the room you need, scarfing on the mould does reduce it a bit, trying to move 16′ planks around dripping with epoxy can be fraught if you are tight for space, it can be fraught anyway!
Dining room, no, you have to eat somewhere. Lounging is not going to be an option while you build so I would go for the lounge, why laugh – a most sensible use of otherwise wasted space, warm and dry with a nice carpet underfoot, brilliant. The Woodlander has only 5 planks so Hull build time is minimal so send the missus on holiday till done. Once the hull is skinned and gunnels in place the remaining fitting out could be done outdoors with suitable protection whilst not being worked on. You will need to fit the mast outdoors anyway to get the alignment correct – from experience it just can’t be done in the shed, unless of course, you have a barn to work in.
Plans, throw the S&T sheet away – we don’t want you backsliding, this IS a clinker build after all. Nice lines – well, beauty is in the eye of the beholder, fortunately we all see things differently otherwise it would be a boring old world. I do look forward to seeing her in 3D and will be happy to eat my earlier words. 5 planks creates issues with the angle of the lands, at the turn of the bilge you will need to make sure that the epoxy filling under the edge of the plank is done well. Because of the acute angle there is not as much wood on the land so you need all the strength you can get. I think you also need to decide at this stage if you are going to build by the Oughtred method or Tom Hill’s with supporting and defining ribbands. How far apart are the moulds, risk of plank sag and inadvertent flats in the hull if too great. 4mm Ply, especially the three ply has a tendency to sag.
The S&T sheet has been put aside for firelighting duty at the next HBBR BBQ. After discussion with wifey we decided to extend the shed roof permanently an extra 9ft x 12ft over the patio, but with open sides. That will keep the rain off all year but still catch the afternoon/evening sun, BBQs will be rainproof, patio furniture protected and boatbuilding will be high and dry. Hooray! 21ft x 9ft roof in total and double doors on the 9ft x9ft shed.
For the Woodlander I’ll make a temporary shed extension under the patio roof to keep things cosy.
After a bit of handiwork with a hammer, 5 T&G panels were removed to give a 49″ door opening on the shed:
Door opening 49in. Canoodle with 32in beam for reference - Woodlander 36in beam.
If the strong back is on rollers there is enough access, so proof of concept! Yes it would be nice to have a 21 x 9ft shed but life is a compromise and we ain’t got enough garden space – I’ll be very happy with 21x 9ft under permanent cover.
There are 11 moulds, mostly on a 415mm pitch (16 3/8in), 5 panels per side like Stangarra.
OK, I, and now the rest of the world, know I can’t get a BBQ lit. I am amazed that a 12 year old malt is no good for lighting it – I thought all spirit was inflammable! Another useful thing you can’t do with it. Just what is it good for? Obviously not for supping – still half a bottle left after the Cotswold BBQ.
‘Shed’ coming along well – when are you going to build – cold weather is on its way and with power prices where they are .. . . .
Concerned about your beam, 49″ door – 36″ Woodlander beam = 13″, I know you are rake like but even so. Are you going to be able to work in the space between the window wall of the shed and the boat, you do need to be able to swing a cat else the quality is going to suffer from your frustration at the enhanced difficulty from not being comfortable. Possibly you can pull the majority of the hull out into the ‘patio’ area. Leaving the stern in the doorway allows you to swing the hull a bit towards the house and give yourself that little bit more room. Don’t forget, unlike a S&T where you have lots of room until you have stitched up and then you are working on a ‘complete ‘ hull, with Cply you have the skeleton from the start and you need room to work on the planks away from the hull. I will be very interested to see how you cope.
The mould spacings are about what they were for Stangarra, I wouldn’t have done her without the ribbands, even so I think I got a couple of flat spots. The ribbands sound like extra work but IMHO they save so much time when it comes to planing the bevel, and the bevel needs to be right, that they are a well worth while addition. They also give you a reference to see how the planking lines are working aesthetically. It might as well look right as wrong, granted it probably doesn’t make much difference to floatability but when you are lost in rapt admiration of your handiwork and the realisation dawns that that plank ought to have been another 10 mm up the stem – well believe me you will be well peed off with yourself. Take another look at the start of the Stangarra tale to see how I made allowance for the ribbands on the moulds. I personally don’t favour the notching moulds idea. It reduces the opportunity to adjust by a smidgen when the line isn’t quite fair. As far as lining the planks – don’t take the designers drawing as gospel, even the best get it a little awry from time to time. The whole thing with CPly is constant eyeing up the boat lines for fairness. I find lots of snaps taken onto the computer and flipped so the skeleton is the right way up helps judge how you are doing. For some reason looking in B&W helps clarify the image.
Work on the shed extension has started. Yes it looks like a building site but its great big-boys fun! I reclaimed many 6×2 by 2.5m softwood planks from redundant pallets at work, all for free with the help of a colleague. The rear girder is butt joined with polyurethane glue to a length of 4.2m and will probablly have a centre support, in addition to support the fence end. The front will be 3.8m wide and I hope it will not need a centre support – if it sags a bit too much then my mate at work will have extra wood for his log burning stove! I might then have to make a Glulam beam by laminating 25mm ply – the Americans produce wood beams of all sizes so there will be a solution. Other beams will be cut down to 2×3 or 2×4 and hung every 2ft between the girders that are about 2.35m apart, then sheets of 9mm ply and a felt covering will make a weatherproof roof.
At the shed end I have used building grade metal joist hangers that give a secure and easy way to support the girders. I have never used joist hangers before but they are perfect for the job.
As you can see there will be just enough room to drag the canoe out and eye her lines for fairness.