• Building a Stacking Pirogue - Blog

    Building the Stacking Pirogue

    Hi all,
    This is a retrospective Blog about the making of my wooden Pirogue (pee-row) which I built around this time last year in 2006. It was by trawling the net for helpfull hints for this project that I came across the SOTP forum, so its about time I gave some back. Pirogues originate from French Louisianna and were made from a few planks nailed together and one laid across the gunwales to make a seat. They were used like pointy punts as personal transport through the swamps, propelled by pole or paddle.

    This pirogue was designed by myself to meet my needs - using CAD software and paper models. It is much deeper than a propper pirogue and desiged around getting the best out of 2 sheets of 6mm birch plywood.

    I live In quite a small house and dont have a garage or similarly large space to build or store a boat under shelter. This is why all my boats are built in two halves that either bolt together or fold on a hinge. Unlike most stories, this one starts in the Middle:



    The centre Bulkhead was built first. Please excuse the poor looking joinery- I dont have any shots of the finished article but you get the idea. The timbers were glued and screwed to the ply before being clamped together and 8mm holes drilled for the bolts.
    With the two bulkheads bolted together the bottom and sides were planed so that they were flush and true. This is important as it is these timbers that prevent the diamond shape that occurs in some halved boats. With the two bulkheads fitting together perfectly I knew that I could built the halves separately and they would meet up in the middle.

    Fitting the sides:

    Instead of buying 2 big sheets of plywood, I bought 4 607x2440 sheets, mainly because this is the same width as the length between my armpit and my fingers (I carried the sheets home in two journeys from my local DIY store) and because I could saw 2 sheets down the middle to make the 4 side panels.
    Tip: two ladders laying side by side on the floor with a gap inbetween works well when cutting a long straight line with a jigsaw.


    Insert
    Because I had cut the panels acuratly I felt no need to sand or plane the edges. With the cut edge down any lumps or dips would be filled with the resin, and probably make the join stronger anyway. The panels were
    screwed to the bulkhead and are shown here temporaily stitched at the bow to give an idea of the shape and size. Oh fk this things going to be massive!
    Can anyone spot the big mistake in the process so far? (other than the bit where I started cutting on the wrong side of the line - top right of the bulkhead - resin fills all!)



    Bottom:

    Sorry, I dont have any photos of marking out or cutting the bottom panels. I think this was done during the heavy snow and I had to work in 30 min bursts before my feet got too cold.



    I lofted some dimensions from my drawing and used the pin and batten technique to mark the curves. Some pirogue builders simply lay the plywood on the bottom and draw round the sides with a pencil - but Im sure I would have ended up with a twisted hull that way, given my workbench was a plastic garden table!

    Hey now that looks like a boat!



    I temporarily bolted the two halves together and stood there staring at it for 10mins. Somehow I didn't imagine it was going to be this big! ( where the hl am I going to put it?) I used parcel tape to hold the bottoms on in the right place while I stitched everything together with cable ties. The bottoms are what give the boat its shape at this stage as they push the sides out a little, which then rise because of the angled join at the ends - in turn pulling up the bottoms to give a good amount of rocker.

    I decided I wanted the sides to come out a little more at the top, making the curves a lot smoother. To do this I took some measure ments and did some maths and made some little angled knees which when stiched
    tightly down into the chines, persuaded the sides to bow outwards.
    insert
    Notice the little lumps where the stitches are. These are small lengths of pencil, that are put in the corners where the cables ties are to aply equal pressure and hold the panels in the correct position - without them the panels would overlap rather than meet.





    These photos (above) also show one of the bow/stern bulkheads one of which will form the floation locker, the other will become a transom stern, I know... I didnt want one but it was necessary for the stacking ok.
    Knees ribs and fancy bits:
    I decided to ditch the little knees and go for full width... ribs? I drilled lots of holes in them to act as tie down points and drainage in the corners. This photo shows the Stern Half before the pointy bit was cut off. The curved corner peices added strength and would have big holes for ropes etc. These holes somehow worked out to be the same size as pint glass holders - funny that

    Its worth noting how few stitches I actually needed - I like to think this is because it was well designed and the peices naturally fitted together rather than being forced - but I think its just the simple naturally rigid shape. There was no need for thawts and the boat was really
    rigid, even before fibreglass. I kept the boat upstairs and carried it down everyday to work on it, so it got knocked about allot and dropped more than once.



    Tack Welding:
    I wanted to remove the stitches so I had to 'Tack Weld' the bits together. With Epoxy you would mix up a filler and run fillets between the stapes. I didnt think Polyester resin on its own would be up to this, so I used 4'' long peices of Fibreglass tape.



    I should have used some resin/woodflower mix to put a fillet in the chines before apllying the tape, but the tape seemed to go into the corners happily without any bubbles - looking back Im amazed this worked but it was strong enough to carry the thing upstairs and back down again the next day without the cable ties.
    If your wondering what all those little dark marks are, they are the result of taking a stanley knife to the ares where the tape was to be applied and cross hatching it to help the resin get a grip. I thought this was a good idea after reading horror stories of Polyester sticth and tape boats falling apart due to delamination. Took ages, made it look tatty and I doubt it did any good, anyways - live and learn.

    Fibreglassing:

    Theres a gap in the photo record here. The fibreglassing went quite smoothly. Took me a while to get used to the cloth tape as I had only ever used matting before.

    Here is the process:

    Mix up some filler - mix in the catalyst first and then add woodflour/sawdust (i used plain flour from tesco) untill its like peanut butter
    Put a fillet of filler round all the joints using the back of a spoon to get a smooth radius. Also get a generous bead of filler into the gap between the bottom and side panels on the outside.
    TIP: put masking tape either side of the joint you are filling - I didn't and had to spend time scraping off the envitable drips and messy bits.
    Mix up some resin, paint some on the joint, lay on the tape and push it down with the brush - you want it wet enough for the tape to go clear but only use just enough resin, too much can cause delamination.

    I let then let the resin cure untill it was hard enough to sand off any lumpy bits by hand - wiped it over with acetone and then put on an extra layer of cloth for durability and rigidity.
    [there is plenty of information avaliable about the stitch and tape bit so I havent gone into too much detail]

    Because I was building the boat in two halves, the stern half was always ahead of the bow (how often can you say that!) What I mean is that while I was waiting for the resin the cure on the stern I was making parts and stitching the bow half. The following photos show the nearly complete stern being tested with the yet to be glassed bow:



    Yup still looks liek a boat to me

    Insert

    And it fits inside too! The bottom rests on the ribs of the other half (which were curved in the middle to clear the keel strip.



    Now we see why I had to have a traom stern. I wanted a locker to keep my sandwiches and camera in, and also a bit of flotation. So had to cut off one of the pointy ends so that it would still fit inside the bow half. I did the cut after all the fiberglassing had cured - I made sure I didnt glass the bit I was going to cut off - used these bits to
    make some rudimentary paddles.

    When Fiberglassing the bow I mixed up some thick filler and appllied it to the stem. I then waited untill it started to gel (thicken but not set ) placed cloth tape over it and moulded it by hand into a radius then gave it a coat of plain resin. The result was an imensly strong polyester stem that could have 1/4'' chunks taken out of it before water would compromise the wood.

    Heres what everything looked like after being glassed in place:







    I gave all the wood a coat of resin to seal it then gave it a final sand over. The outside was finished in Green Dulux Weather Sheild paint - your meant to paint you front door with it but I figured that expensive paints get scratched too, so as long as I dab a bit on occasionally and keep it out of the rain it would do the job. The inside is just bog standard exterior paint - cactus green



    Notice the well above the bow locker, the idea was to stop splashes and drips from wet ropes from entering the boat and instead running out of holes drilled in the sides. With the top of the locker being lowered I could also fit a good sturdy dowel as a carry handle.

    Testing:
    With the paint fully dried - well nearly I loaded the two halves onto a folding sackbarrow, and tied it on good and
    tight. I had fun doing manouvers round the garden. Because the wheels were at one end it was a bit heavy, but
    managable and under control.



    I then set off down the road towards the river - I got a few funny looks but the boat got a fair few aswell and we soon arrived at the river bank. The two halves bolted together around a set of foam rubber washers that made the seal. This was made easier by sliding the bow half into the water first so that it was at the same angle as the bank and could be lined up with the stern.
    I had never been in a canoe type boat before so didnt really know what to expect in terms of handeling. It was very manouverable due to the decent ammount of rocker despite the shallow keel I had added. Stability was excellent and It was quite fast through the water. The tracking improved greatly with two people onboard so we headed up
    the river. We grounded at one point very solidly and away from the bank, after shifting some weight and lots of scratching sounds we were off again.



    I only managed a few short trips out in this boat before starting another project. But in that time I paddled up onto banks, scraped over shallows and dragged it in and out of the canal. The paint held up surprisingly well with only 2 or 3 scratches through to the resin, some whitish scuffs and a chunk out of the keel due to an encounter with a motorbike engine.

    Now then did you spot the big mistake early on in the build?
    I simply screwed the sides onto the bulkheads, dry, no glue, no resin. On the 3rd outing I noticed a small pool of water comming from the joint - it wasnt a problem and stoped after 10min (probably as the wood swelled)

    Thiswas an easy thing to fix. After finishing my day on the water I sanded back down to the wood and left it in the sun to dry. I then made a small tool that was kind of like a tiny hooked knife and proceeded to carve a deep V shaped channel around the joint between the plywood and the bulkhead. Some waterproof putty, resin and a couple of coats of paint she was back on the water.






    Really enjoyed building the boat and would reccomend it to anyone. I sold it to a very friendly couple. They already
    had a sevlar inflatable but had inherited some dogs and didn't want it to burst. They arrived in a little car and it
    was obvious why they had chosen the stacking boat. It fitted perfectly on their roofrack and they have written to
    me since thanking me for building them their boat. Hopefully they have looked after it and its still bobbing up and
    down the canal.



    Congratulations for making it to the end!
    This article was originally published in forum thread: Building a Stacking Pirogue - Blog started by Hobgoblin View original post