28th of January, 2021.

The first job on the agenda today, was a little bit of trimming. Those paying attention at the end of the previous post may have noticed that there was a slight ‘bump’ or mismatch between the outer edges of the forward and aft bottom panels. In the plans, this was considerably worse, as the dimensions from one to the other are different by a whopping 3/8ths of an inch, or 9.5mm! I’d trimmed most of this back when I trued-up all the panels, but I’d left a little to be adjusted once I had it in-situ, so as be able to eyeball the curve and make it as fair as possible. 60 seconds on each side with a surform (that long narrow thing with the yellow handle that you may have noticed in some of the pics) was enough to make it look pretty.

I now pre-drilled all the holes along both outside edges of the bottom panels. Next I took the port side panel and laid it over the bottom panels, roughly lined up. Starting at the butt joints, I drilled and tied one pair of holes at a time, working my way back to the stern. Once done, I repeated this, moving from the middle, forward to the bow.

With the help of some more hoochie cord, I temporarily placed one of the two bulkhead panels in place, to help prevent the side panels from flopping into the boat as I worked. Using a polystyrene box to help support the forward end of the panel, I repeated the process along the starboard side.

It was at this point that I significantly deviated from the instructions. Both the middle bulkheads are supposed to have already had curved laminated beams made and fitted to their upper curved sections before now. However, I had yet to complete this step, as I was still waiting on delivery of the epoxy and thickener I needed to laminate the beams. What I was supposed to do at this point was mount the completed bulkheads in place with screws and zip-ties, attaching them to both the bottom and side panels. However, I could see no reason why I couldn’t simply carry on and mount the bow and transom (stern) panels, and then fit the bulkheads after I’d finished them.

First up was the bow panel. This is a flat, ‘v’ shaped piece, which forms what sailors call a “pram” style bow, as opposed to the more normal pointed bow. To get the bottom and side panels to align with the edges of this panel involves pulling everything up and in, towards the centerline. This takes considerable effort, and I’ve seen everything from thick rope to ratchet-straps used to do it. This has always struck me as overkill; I had a much more nautical method in mind. A simple device known to sailors as a “Spanish Windlass”.

It works like this: Pass a line around the objects you wish to pull together, and tie it into a loop. Pass a stick, pole, or other long thin object through the loop and twist it around once so as to make a small loop around the stick. Now.. keep winding the stick around and around, and it will steadily pull the large loop tighter and tighter.. and tighter. So long as the line is strong enough (and you don’t accidentally let go of the stick!), it’s possible to put incredible amounts of force on the object of your attention.

So I whipped up a quick loop of hoochie cord, passing it under and around the two bottom panels, grabbed a scrap of 6mm plywood to use as a stick, and started winding it up. In no time at all, I had everything pulled together nicely, and could start stitching it all in place.

If you look closely, you will notice that on the starboard side of the Spanish Windlass, the cord has actually pulled right through the 4mm plywood, down to the hole drilled for the zip-tie! It actually made quite a neat “cut.” The noise it made in so doing (sort of between a bang and a thud) scared the daylights out of me for a second. But I could see it was still holding well regardless, so I quickly drilled holes, put in a bunch of ties, and released the pressure. Interestingly, the tear has made no difference whatsoever to the ability of the zip-tie at that point to hold things in place! The benefits of having a flat strap in a round hole, I guess. When the panels are expoxied together, that will serve as an excellent repair for the damage. When finished, nobody will ever know it was there.

All that remained was to drill holes and stitch the transom panel to the stern. First along the bottom panels, and then the sides. Simple.

Transom stitched into the stern of the dinghy.
The basic hull is done!

A series of shots of the boat.. basically this is just me admiring the lines of the hull:

One small problem remained to be solved, however. In some places, rather than neatly butting up, edge to edge, the panels overlapped slightly. If you look closely at some of the pictures, you’ll probably notice it too.

For a while I was baffled as to how I was going to correct this. The hull was too awkward, too flexible, too light and too wobbly for me to simply try and push/pull things into place. But then I had an idea. I could slip the end of my 1 metre steel ruler between the panels, and carefully (and gently) lever them into place, then carefully remove the ruler. This turned out to work beautifully, and gave me a lot of fine control, enabling me to get all the joints aligned perfectly. Once I had all the panels aligned exactly the way I liked, I went around and snugged all the zip-ties tighter, with the exception of the underside centerline ones. (For some strange reason, these days I try to avoid working upside-down, laying on my back on a concrete floor!)

Aligning the panel edges with the aid of a steel ruler.
So easy when you know how!

In retrospect, using 4mm plywood for the hull made some things easier, and some things harder. The additional flexibility of the thin ply meant that introducing bends and curves into the panels was a lot easier than it would have been with the much stiffer 6mm plywood. However, the lightness (I would estimate the 4mm ply weighs just 55% of what the same amount of 6mm ply weighs) meant that I had to be more careful in handling the boat. Then there was the way the panels mated up to each other. With 6mm panels, the near-vertical sides could simply sit on top of the bottom panels, right at the edge. But with 4mm plywood, this wasn’t possible, and they had to mate flush, edge-to-edge, even at quite open or very tight angles. Until I figured out the ruler trick, this wasn’t easy to achieve.

Total time spent on the build to this point: 38 hours.

Next: The aft buoyancy tanks.

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