There’s a primal attraction to a small floating boat that will carry at least one person and possibly a dog. It’s so handy – cross or explore a creek and not get wet, get to a bigger boat anchored offshore, give kids independence and adventure on the water and enjoy rowing with no noise but the creak of oars and ripple of a bow wave.
Acquiring such a craft is tricky: TradeMe does not deliver a stream of small dinghies at reasonable prices; they are invariably heavy, beaten up or involve pickup costs close their purchase price. So what to do? How about finding a dinghy, ideally a pram dinghy, on a beach somewhere and stealing it?!
The plus with a real dinghy is that you can see how it floats and rows in the real world, not rely on claims on the internet and pics of them on glassy seas – you can even befriend the owner and finagle a trial row to see how it feels.
To steal a dinghy without getting a criminal record is possible with some ingenuity and energy. You can copy its shape using fabric, tape and a felt tip pen, then transfer fabric patterns to plywood and then build the boat using the stitch and tape method, which is a great shortcut for amateurs like me.
You need to pick a good day, ideally with no wind. Have the donor dinghy upside down and start making your patterns. I used non-woven polyester cloth, a fabric that is low cost, dimensionally stable and lies flat. Lie pieces of the fabric over the four panels: transom, bow, bottom and topside – one at a time. Tape it down in a few places with overlaps on the edges and get your felt-tip and mark the edges of the boat on the fabric. You could possibly create a complete line, but this will likely pull the fabric and distort it, so settle for points that you can join up later with a batten when the fabric’s lying on a flat surface.
Now cut out the panel shapes and return them to the donor dinghy and check they’re accurate. You’ll need to make manual adjustment for rubbing strakes and the keel strake (go to its base and add half its thickness to get full panel size).
As this process was a little flakey, I thought it prudent to check the panels for fairness by first cutting them out in 3mm MDF and stitching them together with cable ties. This was good practice for the real thing when I’d be cutting the ply.
I made a jig to space the tie-holes with a piece of wood 120mm by 15mm with two 4mm holes on the centreline, 10mm from the ends. Once you have a starting hole in two panels at, say, 10mm from an end, you can drill holes down the edge of one panel then the other by swinging the jig around pivoting it on a spare 4mm drill bit. That way the holes on different panels, such as bottom and side, match up.
MDF to plywood
Good quality plastic cable ties are best as low quality ties can snap under load. Use 4mm by 100mm to allow loose assembly and then gradually tighten them up to get the plywood edges just touching.
Having the bow, transom sides and bottom all loosely connected, and working my way around tightening the ties, gave me a floppy but recognisable pram dinghy.
Now to get serious: 6mm Meranti marine ply was my choice – 4mm would be OK but less robust. Doubling the thickness by gluing ply battens on flat areas of the bottom will be necessary for both. And a 10mm wide rim around the bow and transom will add surface area for the topsides and bottom panels to attach to.
I made up a few metres of double thickness ply strip to use on bow and transom edges, which can also be used on the topsides to support the seat at the bow and stern. The middle seat will needed more support with a double thickness running all the way from the gunnel down to the chine.
I traced around the 3mm MDF to get the shape onto the ply and then used the hole measuring jig to put holes around the edge of the panels where they join.
You need time and space and energy, but that’s all the Stephen Hawking input required. Just keep at it. The internet has great videos of step-by-step stitch and tape construction and coving – a plastic ice cream container lid is great for making coving scrapers in various radii.
I built my pram sitting on an old door sitting on two sawhorses and was particular about making the panels identical. Having the panels sitting with edges aligned consistently from bow to stern and the same on either side is important. Once cable tied in place, I measured the diagonals for square and got within 3mm.
I kept the weight down by building a hollow main seat like a thin box: four pieces of 20mm ply on edge forming ribs between two 6mm panels keeps the seat stiff and light and open underneath with no prop to the bottom of the boat. To have space on the centreline in middle of boat for ferrying a fuel tank or chilly bin, bag or anything heavy you want in the middle and low down is a big plus.
Building in buoyancy by boxing in the front and rear seats adds weight and time, but it provides stiffness and adds hugely to safety – having the seat top overlap the bottom with a lip makes finishing the edge easier and doubling the thickness on the edge adds to robustness.
Before cutting up good ply/timber it pays to making templates for the seat panels and the keel strake – 50mm wide battens of 3mm MDF and a hot glue gun are great for this.
If you have built the dinghy light enough and you are strong enough to carry the dinghy on your back, the seat edge overhang makes this much easier.
The central keel strake would usually have a brass strip, however to reduce cost and minimise screw holes below waterline, a 4mm thick piece of kwila or decking hardwood glued to the strake makes a good wear strip that can be planed off and eventually replaced when badly worn.
Knees in the corners can be 6mm ply with a double thickness on the edge.
Old wooden dinghies often have rowlock blocks on the gunnel that have been broken off and re-attached, so having a large surface area to glue them on to and keeping the pivot hole close to side of the boat was important for structural integrity and longevity. I laminated them using a mould made from two pieces of Melteca trimmed and joined at the correct angle, with wax rubbed on for release.
Building the hull is relatively straight forward; adding seats, knees and stiffening battens to the floor takes time. Jobs that are separate and simple are good to list and tick off. Save the satisfying jobs like planing an edge until an unpleasant job is finished – it’s a rewarding discipline.
To save time expense and weight, I only glassed the bottom with a double layer of cloth on the chines, bow and stern corners, as these suffer the most knocks.
Piping bags for coving resin paste are available online and are a good investment, giving a neater job and saving resin and cleanup. Likewise, running masking tape on glue edges and removing it when glue is wet is well worth doing. Using cheap disposable brushes with 20mm cut off the hairy end work a lot better for resin application. Covering the surface of coving and wet laminate with peel ply also reduces ongoing surface prep. Scraping/sanding hard epoxy glue is frustrating, so good to avoid.
When it comes to the fairing and painting, I found a few key things: quality paint, quality brushes and the right music! I thought a cheap disposable brush would be OK for primer. NUP! Sanding and two more coats with a decent brush were needed to get it back to being ready for undercoat. The Altex one- pack boat paint (made in NZ) is very flattering for amateurs when the prep is good, but exposes shortcuts on previous coats.
YouTube does a great job for boat building, especially when you have started, but it can also delay starting a job and absorb much time when researching around a sticky issue. There are times when you need to throw yourself at the task. The details of the ‘how’ often become apparent as you get into it, just like starting the build. It’s a succession of small steps.
It’s an immensely satisfying project to build a boat, float it, and row it. The next one, where it will ultimately be sailed, will be even better.
Words and Photography by Stewart Halliwell
