29th of January, 2021.
Ahhh. the buoyancy tanks. Now there’s a tale for you.
Man. I still can’t believe just how much hassle these gave me. Or in other words, how I managed to mess them up. Twice. You’d really think such simple objects would be, well… simple.
As it happens, there are at least three different ways to assemble the assortment of panels that make them up. And two of them are WRONG. Yours truly, being the genius that he is, managed to find both of the incorrect layouts.
Why is this such a big deal?
It’s a combination of things. Firstly, unlike all the other bits of the dinghy, they’re small. So there’s the temptation to play with them, even before you’ve started assembling the rest of the boat. (Ask me how I know this. Actually, no, don’t. Because I’m about to tell you anyway.) Secondly, the instructions suggest, quite sensibly and correctly, that if you’ve never done any work with epoxy or “filleting” epoxy (more on that in upcoming episodes), then making the buoyancy tanks is an ideal way to gain some experience, before getting to the main event. I should probably mention in passing that yes, I have worked with epoxy and fibreglass before. Once. A long time ago, in a galaxy far, far away. And it was only a small project. And no filleting was involved. So.. entertaining times are probably ahead of us.
I would say, heaven help you if you decide to epoxy and fillet the tanks before you’ve even begun putting the dinghy together. Because if you get it wrong, and the odds are good that you will, then your options are to spend a lot of time with a heat gun and scrapers (& a respirator mask with VOC filters!), trying to dismantle the mess you made, or to give up, get a bit more plywood, and start over.
So yeah.. back before I’d even moved out of the house in Melbourne, I took a look at the six pieces, and tried to figure out which bits went where. You’d think that given how they’re labelled ‘Top’, ‘Front’, and ‘Side’ in the plans, this would be fairly straightforward. As it turns out, no, not really. You see, the various dimensions along the edges are cunningly arranged such that, it’s possible to place edges together that fit together well, and “look right”, even though they’re not supposed to be next to each other!
So I cheerfully went ahead and marked the edges so I knew which edges attached to which other edges (heh heh.. I’m no dummy!), drilled matching sets of holes, and zip-tied them together. I was pretty pleased with myself. For a while. But slowly it dawned on me that something didn’t seem quite right. I visualised the inside of the stern in my mind, and tried placing the two objects I was so proud of into it. Well, poop. They were clearly wrong.
Fine. Cut all the zip-ties off, and start over. This time with a clear picture in mind of the tanks’ relationship with the inside of the hull. All the wrongly placed holes I’d drilled? Well fortunately, just like plaster and paint, epoxy can hide a multitude of sins. Thinking carefully as I went, and with much reference to my mental image (measure twice, cut once!), I rearranged the pieces, double-checked my work, re-marked the edges where they were supposed to go, drilled more holes, and put it all together. This time, it looked right. Trust me, I checked. I even took a look again at Ben Clardy’s video, which showed them mounted in place. (He didn’t have video of putting them together.. hmm.. now why might that be, I wonder?) I just didn’t check physically, since that wasn’t yet possible.
Satisfied, I cut off the zip-ties, bundled up the pieces, and got back to packing stuff for the upcoming move to country Victoria.
Fast-forward to the present day.
I wander out to the shed, spend a few minutes admiring yesterday’s work, and then, using a pair of pliers, proceed to get all the zip ties (except the centerline ones) as tight as I possibly can. Now it’s all about closing up the gaps, getting the panels fitting as closely as I can. When I’m done, daylight only shows through in a few places. And the gaps are only a millimetre or two wide. Well within the 3/16th of an inch (5mm) that the plans specify as being just fine.
Right.. time to see how well the buoyancy tanks fit! I gather up all the pieces and zip-tie them together again. Thank goodness I was clever enough to clearly mark everything! I put them into the stern of the dinghy.
Well, crap! (No, that’s not the word I used!)
FINE. <insert sounds of snarling and grinding teeth here> Cut zip-ties off. Place the bits in the boat, and start playing “put the jigsaw puzzle together.” Ok. Making progress now. This goes here, that goes there. Hmmm.. ok, so this edge has to go that way around, to match that angle. Makes sense now. Mirror image it all on the other side.
With that finally sorted, I set to work, marking, cutting, shaving, trimming, until all the panels are a reasonably close fit to the curves they have to match up with. I won’t be able to get them exactly right until I’ve fitted the midships bulkheads, because that will probably change the internal shape a little, but it’s good enough for now. I can finally assemble them and give them a dry-fit test.
Drill yet more holes. Zip things back together again. At last. They fit. As mentioned, they still have some final trimming to do, to get a closer fit along the curves of the hull, but THEY FIT!
In hopes of making life easier for anyone reading this who is building their own Chameleon Nesting Dinghy, I’d like to present the following information.
The plans are drawn in such a way that, when assembled, you can choose to have the best face of your plywood all on the inside, or all on the outside, of your dinghy. (Yes, even AA grade marine ply has a good face, and a not-quite-as-good face.) Generally speaking, you’ll usually want the best face on the inside. As you can see in the photos above, the buoyancy tank panels are the same (good faces visible on the outside of the tank), with the exception of the starboard side panel. (This one exception is just a side-effect of having to fit all the hull pieces into just three sheets of plywood.) This is the case for the tanks in the diagram below, assuming that you do all your lofting on the best face, which you really should be doing anyway, as it lets you get the sharpest possible lines (and it isn’t as rough on your pencil point).
Now that all that’s clear, I’d like to help you avoid all the stress and hassle that I went through with the buoyancy tanks. So, take the plans you’ve printed up, and go to plywood layout sheet #3, where among other things, the panels for the tanks are located. In addition to Front, Top & Side, mark each of the tank panels Port or Starboard, as shown below. (I’ve removed all the other panels, and all dimensions and gridlines, so as to ensure this diagram is useless for anyone who hasn’t already bought the plans. I don’t want to be accused of making Danny’s hard work available online for free!)
With these small but important added details, and knowing which way the good face goes, you should be able to put your buoyancy tanks together correctly the first time around!
Having gotten the buoyancy tanks dealt with, I enlisted the aid of my housemate to help flip the dinghy upside-down (I was a bit concerned about how floppy it might be, and didn’t want to accidentally dislodge anything). This was so that I could more easily access the centerline zip-ties. I then used the steel ruler trick to ensure the edges mated flush along the centerline, and pulled the ties together as tightly as possible. After that, it was finally time to cut the tails off all of the 102 zip-ties that are holding the dinghy together. (Yes, as I cut them off, I counted them!) Flipping the dinghy back upright again was easier, and I managed this on my own.
And, that’s as far as I can get, until such time as the epoxy, thickener and fibreglass tape arrives in the mail.
Total time spent on the build to this point: 40 hours.
Next: Laminating the bulkhead beams.