What is the coolest thing that comes in pocket size? Well, a pocket submarine of course!

Small submarines are often called pocket submarines and although the real life ones won't actually fit in your pockets, the one in this Instructable will. It will fit into your pocket and in the water it really does dive and resurface, thanks to different methods of depth control (see step 6 for a movie and step 7 for an additional method).

Above that, it is easy to build from a few components. Apart from the soldering in step 2, which you can do in preparation, you can easily make it in a childrens' workshop. The total cost of materials can be limited to about 6 euros.

This submarine is so simple because of the use of a laminated/moulded solar module, waterproof by itself and by skipping any attempts to waterproof the connections or the motor. Don't worry, many simple electric motors do withstand running them immersed in water. Some of them might corrode somewhat after use, making starting up the next time a little difficult, but For several this will not even be a problem (for hints on which ones see the next step).

"What about the current leaking through the water?" you might ask. This will indeed give a slight energy loss, but it is very limited and the energy comes for free from your solar cells anyway.

I added a short video on March 27th (long video still in step 6):

Step 1: Parts and Materials

- laminated/moulded solar module
- low voltage, low current electric motor
- propeller
- floating material (see below)
- 2 x 15 cm flexible electric wire
- For an optional "periscope" depth control about 1mm diameter steel or brass wire, 10 cm long and piece of clear plastic about 2,5 x 2,5 cm.

Tools and various:
a soldering iron and some solder
hot melt glue gun + glue
some superglue
hobby knife
waterproof markers to decorate

Here are some specs and hints, but feel free to try out alternatives:

Solar module:
Make sure you use laminated or moulded solar module. Do not use simply encapsulated solar cells. Trying to make the latter waterproof will not solve the problem of condensate and will never reach the level watertightness that comes ready with the laminated/moulded ones

I use a laminated solar module specified as delivering 250mA at 1V, available at Opitec under reference number 103.890 or at Kelvin, number 260190 (at quite a higher price). Using an alternative module delivering 300 mA at 1.5V gives the sub a little more boost for a couple of euros more.

Electric motor:
I get very good results with the "FF 130" motor available at Opitec (ref. 224.079). With this motor I left the sub in the pool for a day, took it out a couple days, put it in again and it was still working fine. The more common "RF 300" (851105 at Kelvin) on the other hand seems not to survive repetitive wet and dry conditions. The motor under ref. 851165 at Kelvin also seems to do the trick. It's open structure will also help it dry quickly. The 1.5 mm shaft however will need some tape added arround it to fit common 2mm shaft propellers.

propeller :
A simple plastic propeller is mounted directly on the motor's shaft. I us the ones available under nr 842.479 at Opitec or 851102 at Kelvin.

Floating material:
The next important thing is the material for the sub's body, giving it its floating capacity. I use 5 to 6 mm thick extruded/expanded polystyrene sheet as found in foam trays, as thermal isolation sold under the name Depron or Climaplan or found under ref. 870.539 at Opitec. It is easy to cut, which is important for trimming your sub. It is rather fragile though, so you will better put your sub in your shirt's pocket, rather than your pants' pocket (the latter is not a good idea with a solar panel anyway).

The amount of material will vary with the type you use and the weight of your other parts. You need it to be able to carry all the other parts, with some floating capacity to spare. Attached is a template scaled to the 6 mm extruded polystyrene sheet (best printed it at 100% by disabling the scale to fit page option when printing from Acrobat Reader). If for example you use a thinner piece of foam tray you should scale to compensate an obtain about same floating capacity. The easiest is to make it to large and cut of the excess material when trimming later.

I have been experimenting with foam rubber and some expanded polyethylene packaging material. This is much less fragile but not stiff enough. You can add (metal wire) stiffeners of course, but that complicates things. Yet another possibility is the use of "Aqua Soft" floating plasticine.
I dont quite understand how the sub dives and rises on its own
The propulsion pushes the sub not only forwards but also slightly downwards (the solar panels doubles as a rudder surface tilted slightly downwards. When the sub comes in the shadow the propulsion diminishes. The forward movement slows down and the downward push is no longer larger than the buoyancy. Keeping it going does require some trimming.
what makes it go in and out of the shadow at the right time? Does part of the submarine make a shadow as it tilts or does it have to be external?
The shadow is external. In the video I looked up the part of the pool where a shadow was cast by a building nearby. But you can also use your own body or some piece of board to cast a shadow and move it to control the sub.
hello.this is such a cool project for me because i have an indoor pool at my house (im not bragging or anything).I prefer RC than solar so can you give me some advice on how do i make a casing and can i use RC powered in water?
Thanks. Sure you can RC in water. Forget the use of 2.4 Ghz or 900 Mhz systems though. But classic 27 to 40 Mhz systems pass through a couple meters of swimming pool water. You can find a vast amount on RC submarines on the net. There are also kits available.<br> <br> A tip I would add to this abundance of information commonly available is that a simple approach is to forget about waterproofing the propulsion. Most simple DC motors will run just fine immersed in water. You can also use motors for all movements, eliminating any trouble of passing the controls from the dry inside to the wet outside. You can use hacked standard servo's in way similar to what I did on my&nbsp;<a href="https://www.instructables.com/id/Sub-Micro-Blimp/" rel="nofollow">micro blimp.</a><br> I used to build simple and small submarines that way.<br> <br> Obviously all electronics and batteries should be in a water tight casing. Chose the casing only slightly larger than needed to fit al components as you do not want to much air inside (to much buoyancy).<br> <br> Also make sure you have the right glue to close holes (e.g. where motor leads pass) for the material your casing is made of. Many containers in PE or PP need specific glue (hot melt glue generally works on them).<br> <br> Good Luck and keep me posted please. <div id="myEventWatcherDiv" style="display: none;"> &nbsp;</div>
I don't know a place for solar panels, so can you use a baterie as well?\ But it is <u>soooooooooooooooooooooooooo </u>cool
Glad you like it.<br><br>You can use a battery to some extend. I've done it before.<br>First make sure you do not leave the battery in the water any longer than let's say a couple of hours. It will corrode and in the long run it will pollute the water.<br>Older types of batteries with fabric at the poles should be waterproofed (see https://www.instructables.com/id/Waterproof-your-Batteries-in-seconds!/)<br><br>It is not recommended to solder the leads to the battery (can be dangerous). Try and make a reliable contacts without. Duct tape should work nicely. If you can get hold of a battery holder, the job will be easier. It will corrode in time, but not right away. You can also make waterproof battery compartment from an old 35mm film canister. An AA battery should fit with a little deformation from the lid. Pass the leads through a hole glued tight. You might need to add some weight to keep the submarine diving.<br><br>Bare in mind that with a battery, it will probably run faster. Don't let it escape!<br>
&nbsp;very nice makes a good gift for a little kid&nbsp;
dude, solar powered propeller beanie
im gunna have to make that and im posting an ible in a week or sumpthin
auuuugh i totally forgot about this. I'll try and make one, i never got the parts either<br />
awseome!!! really like the way it is solar powered!!!!
how does the motor work under water? it would fill with water and not work
It does work filled with water. The conductivity of water is that much lower than the conductivity of the motor, therefore it does not have much influence. You can see it as a high ohm resistance in parallel with the motor and some extra mechanical resistance, but it still works fine. This does not work equally well with all motors. It seems to work best with simple but good quality motors (see step 1). Some motors stop working after some repeated use, probably due to corrosion. But some keep running time after time.
sorry capacitor dog on the keyboard
a capister would be good who whould want a slow submarine
1-I DONT THINK ITS SIMPLE 2-Makes my head hurt 3-if ur like me mabey u should look at the "how to open a banana like a monkey"
1. "Simple" is a relative notion of course. As submarines go, I do believe this is a simple one. 2. Sorry for that 3. That instructable is indeed much more fun than simply telling to start at the other end.
1. ok <br/>2. again with the simple thing <br/>3. nice instructable non-the-less =P<br/>
nice, indeed. anyways, isn't this switch better?connect one wire to the green thing and the other to the thing connected to the balloo and there u have it, a water level switch(sorry poor quality, I was kinda sleepy when I made it, and there's no worse image editing program than paint...)
Dear Awkrin, A water switch could indeed be a good solution in many submarine and related projects. And you made clear drawing if the principle. It is however somewhat more complex than the extremely simple system explained in step 7 of this instructable. Also, the start/stop effect might be difficult to trim as these pocket submarines move slow and have little inertia. Actually, I recently had the chance to shoot some video of a slightly different little sub I made in a children’s workshop (it was battery driven, as it was used in an indoor pool). I added the video to the step 7. It shows the explained depth control system works very well.
then u a capacitor to make the sub get some boost while in water..
you already got my vote!
I love it! I am definitely looking forward to trying this out.
I'm sure I'm your biggest fan! How I love creative and inspiring people like you... I'm so happy I got got to know you! Veerleken xxx
kool :)
DUDE this is so cool.
You got my vote.

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