Having looked at the prices of the commercially available WTC’s for my Steve Neill Blueback, I decided to try and build my own. Having asked plenty of questions and looked at hundreds of images of both commercial and home brewed designs, I came up with the following design….it utilises a length of transparent acrylic tube (bought from ebay) two plastic screw on lids from the large sized instant coffee jars from the local supermarket, a length of grey plastic water down pipe and a strip of either plastic or aluminium to install the internal equipment upon. All the parts are easily available and all of them are easy to work with using just basic hand tools ( I don’t have the luxury of a fully fitted workshop any longer, my first wife and her lawyers saw to that….) and all the materials are easily glued together with either superglue, plastic solvent or epoxy glues.
Having bought the acrylic tube of the correct diameter (depends on your personal needs) I used 80mm for the Blueback as the coffee jar lids fitted nicely, cut it to whatever length you need for your particular boat, sand off the cut edges perfectly smooth with a sanding block, and place to one side. Take the length of grey plastic water down pipe (easily available from plumbers merchants, DIY shops or even builder’s rubbish skips) it needs to be as close as you can get to the next (internal) size down to your acrylic tube, so it sits well inside the tube. Cut it to the same size as the outer tube, then mark off and cut it into a U section approx 1/3rd of the outer tube’s diameter….this will depend upon your needs for internal fitting out with your equipment and how and where you place the servos/rx/batteries/pumps/etc. Having cut the tube, sand all the edges perfectly smooth and level, take your time over this and get everything level. Be prepared to make a mess during this stage, sanding this stuff leaves a thick layer of shavings everywhere, so keep the hoover close at hand if you value your domestic arrangements….
Once sanded level, take the strip of either plastic or aluminium, whichever you prefer, and cut it to fit the top edge of the plastic water pipe…once trimmed level, you can either fit the internal equipment now and then glue the strip to the plastic water pipe, or glue it together first and then install your internal pumps/servos/batteries/etc, the choice here is purely personal as to which way round you complete this stage.
You can either cut out the strip to sit your equipment into, or attach everything to the top, again it’s a personal choice. I used a combination of both ways for mine, which left me with a handy space under the tray to slide the main battery pack into, tuck wiring away neatly, etc…it all depends on how you set out the internal equipment layout.
Next, the coffee jar lids have to be slightly modified….it’s a very simple job, all you need to do is to sand off the internal screw threads where the lid screws onto the glass jar, and that’s it. Being plastic, you can glue items such as rubber bellows or plastic water/air pipe with epoxy glues, providing you rough up the areas to be glued first with sandpaper. I added an thick internal plastic disc to the stern end cap on my WTC, just to give the lid some support as I attached the main drive motor directly to the lid. You can also make up a couple of different lids set up ready for single motors/dual motors, and if you have worked out your internal equipment layout about right, you can then simply just swap end caps and use the WTC in two or three different boats, as long as it fits the boat. And if you make a mistake or decide you need to change any internal layout, spare lids are very easy to get hold of, so it’s no great disaster if you do something wrong.
All outlets such as water inlet/outlet pipes, control surface push rods, the extension to the radio on/off switch, and any external wiring are fed through rubber bellows, which are filled with waterproof grease. The main drive motor shaft exits through a brass bush with small ‘O’ rings either side to keep water ingress to an absolute minimum, so far it hasn’t leaked a drop of water during submerged trials in my indoor test tank, aka the bath.
You can use different diameter tubing and different sized lids to suit your personal applications, but the basic principal is the same whatever sized tubing you need. Just make sure the coffee jar lids fit tightly over the acrylic tube, if you are at all worried about the fit, just wind a few turns of plastic insulating tape over the join to make a perfect seal. I filled mine with several heavy tools…files, drill chucks, spanners, etc and dropped it into a bath of water overnight….in the morning the tube was as dry as it was before I dropped it in.
And there you are…a cheap and easy way to build a WTC for any submarine model. My coffee jars came from Somerfields, their own brand of coffee, but I’ve no doubt that other supermarkets jars can be pressed into service. If you don’t drink coffee, have a look around your local recycling centre. Most people don’t bother to take the lids off their clear glass jars when they drop them into the bins, so just have a quick look around….but don’t cut your fingers when poking about in glass recycling bins.