Do it yourself remote control vehicle basics?

That’s a bit tricky. R/C by itself is relatively simple though; the problem is elsewhere.

For basic R/C, ou have the transmitter, and the vehicle has a receiver, and some things to take the signal sent from the transmitter to the receiver and make the vehicle do stuff. Those “things” are often servo motors that move some part of the vehicle, whether it be turning the front wheels of a car, moving the rudder of a boat/sub/plane, or actuating the carburetor of a small fuel-powered engine. Yes, some R/C vehicles use small 2-stroke engines, but even though they are called “gas powered”, they actually run on special fuel; trying to run them on regular gasoline will not only not work, but will probably do some damage. If you’re building a sub, odds are that you’ll be using electric motors; they are about the only way to move a sub without a snorkel, and electrics are FAR simpler than “gassers” anyways. Trust me, you really don’t want a gasser as your first.

Electric-powered vehicles often also have an Electronic Speed Control (ESC) that allows for controlling the speed of an electric motor with no moving parts; this a stark contrast from the old mechanical speed controls that used a servo.

That is the control end of things, and it is actually simpler than it would sound from the word count above. An electric car or boat will have one servo for steering, an ESC between the battery and the motor, and both of those will have a control wire plugged into the receiver. Four connections; that’s it!

Boats and subs have issues that transcend radio control though, and that will be your undoing. See, the motor itself cannot be in the water, but the props to move the sub/boat must be in the water. That means you have to have something along the driveshaft that seals water out while allowing free rotation of the shaft.

R/C subs have their own special requirements for diving, which you can read about here. But suffice it to say, despite having quite a few years with R/C cars under my belt, even I would be a little hesitant building my own sub. I would just get a hobby-grade kit (not one of those rinky-dink toys) and go from there.

My young teenage son and I had a lot of bonding time together racing electric R/C cars and trucks. I’m with @jerv , a kit is the best way to get started.

I believe that when submersed an antenna must reach above the water line in order to receive signals from the transmitter. Also, I think that some form of automated surfacing would be needed in case problems arise with motors or depth and steering controls.

Cool when it works: https://www.youtube.com/watch?v=b056Enh1oCE

Hit your local hobby shop if there is still one around you, especially the ones that sell train sets. They’ll have all you need. It’s easy and there are all kinds of kits and goodies to do this.

@Bill1939 Radio range is a bit more of an issue with subs than with surface vehicles, but given the size of the sub and the fast that a hobby-grade R/C transmitter has teh range to control an R/C car in a ¼-mile bike track (yes, they sometimes run “super speedway” races on those) and drag strips (here is one going >180 mph!), I would say that you would lose sight of your sub before you ran out of radio range… if you use a HOBBY-GRADE controller!.

Now, by “hobby-grade”, I mean something better than you’d get by gutting a Walmart truck; something like a Futaba 2DR, though I would pring a little more for a 2.4GHz system like a Tactic for a sub, though for a car, I prefer pistol-grip transmitters. All of those are available relatively cheap, and will have enough range to control the sub at ranges where you won’t see it.

As for the other, if you follwed the link above, you will see that some subs use “dynamic diving”. What that means is that, at rest, they naturally float/rise, and will only dive when moving. You can control their rate of descent by controlling their speed; if you slow down or stop, they start to come back up on their own. Quite handy if you do manage to lose radio signal or the battery dies while submerged.