Basic (stupid) ESC +2.4ghz receiver question
 

Hello all,
I'm new to modifying my rc boats. I want to upgrade the ESC and motor brushed to brushless, and higher amp esc. I bought a UDI001 Venom, and tore its guts out and transplanted it into a Walmart/Target Super Air Nautique. Its a cool little build, but the boat is under propped now, and the motor is running a bit hot for my liking. Doesn't go as fast so the water cooling isn't as effective. I wanted brushless before I figured out any of this anyways. So, my UDI001 has a single unit (or what appears to be) ESC/Receiver. I took apart the little black box that it sets in, and it is caulked or glued solid. You can see nothing but the antenna, and wiring going out to the servo, battery, and motor. I was hoping I could take the existing receiver off and use it with my new ESC, does anyone know if this is going to be possible from what I have described? And if not, I suppose I need a new receiver to make it work. I know I will need a 2.4ghz, but what else? Am I going to be able to keep my steering and throttle trim settings? How will this wire in? do I take the wiring leads for the servo from the ESC and run to the receiver and run wiring from the receiver to the servo? I'm lost here.

Just out of curiosity, why are you trying to use parts out of a $45 toy boat to retrofit a $25 toy boat? Toy grade parts don't have the capabilities of hobby grade stuff. With hobby grade parts, you can install a brushless motor with a matched ESC, be able to use better battery packs and have a radio system that will have longer range and, if something goes wrong, it's repairable or replaceable. I just went and looked up your two toy boats and and wondering why you're spending the time on them. You're $45 UDI001 is only good for 15mph according the the Walmart website, making it not really worth the time.
To answer your question about using one boat's receiver with the other boat's ESC, the answer is probably going to be NO. If it comes in a big block, that usually means the receiver and ESC are built up as a mixed unit on a single circuit board.
If you want to upgrade your Nautique, you really need to think about spending some money on quality parts rather than trying to mash together parts from two boats that are really only good to run in a swimming pool

Under propping rarely causes motors to overheat. Too much prop overloading the motor and causing it to run slower does that, as does not having working water cooling if the original was intended for it. If it isn't going as fast as intended, a smaller prop spinning faster gives a faster boat and longer run time with a cooler motor at the cost of a bit of lost accelleration.

As Hydro Junkie said, if it is a single board, or a sealed box, it is likely to be proprietary, i.e. not intended to work with standard items. Having said that, if a standard servo has been used, the black wire will likely be ground, the red wire +5 volts (or thereabouts) and the white will be signal. Or, on many, brown, red, yellow in that order.

I suppose I should have elaborated a bit more. The boat is 2" bigger than the UDI001, and probably 5x the weight. Not to mention running wet (because of increased weight and being a submerged prop, as it was designed for surface drive. In order to achieve similar speeds, the boat will need a more aggressive prop, or faster motor. Needless to say, the motor does have more load in the set up than what it did in the Venom boat, and the slower speeds are not doing any favors for the water cooling system, but the motor is still able to reach about the same RPM.

I am wanting to find a brushless motor for it anyway. It shouldn't run as hot as the brushed 370 to begin with, but I doubt the current ESC will work with one. and if I replace the ESC for an ESC for a brushless motor, then I lose the receiver. Because Hydro Junkie was right, It is a single circuit board. And yes, it uses a standard micro servo.

I think I may have found my own answer. But I need to consult as I am no expert here. The ESC and receiver of the UDI005 are separate units. it is a brushless boat. So I am thinking this should work. I have found the receiver for that boat on Ebay for $8.99. Now, my reservations. The remote has low battery indicator, low signal indicator (range), and steering and throttle trim adjustments. I would LOVE to keep the functionality of these. As far as I can tell, all of these things are done by the receiver, correct? Or does the receiver just send the signal to the ESC which houses the brain for these functions? Assuming all of the settings are controlled in the receiver all I would need to do is find a brushless motor ESC combo with reverse capabilities to maintain full functionality of what I have now? Or does the ESC play a part in the low battery/throttle trim settings? Is this something that can vary depending on the units, or is it straight across the board?

A bigger, heavier boat, to go as fast or faster than another, will need more power. Since a battery is an energy store, and power is the rate of using energy, more power = faster use of energy, or shorter run time with the same battery.
The radio transmitter takes information from the channel controls (sticks, knobs, buttons, whatever) places it into a stream, then transmits it. Some modern sets, not just 2G4 ones, have the capability of modifying the behaviour of the data. In older basic sets, this happened in real time, the data was transmitted serially.
The receiver takes the data signal that has been transmitted.and distributes it around the output channels. Old (pre 2G4) sets looked for the "end of frame" indicator, then started working on the new frame when it arrived, distributing the data contained within each segment from the frame to the appropriate output pin. With modern digital systems, there is scope for the manufacturers to introduce lots of confusion.
In simple radios, the behaviour is much as before, Data that starts at a stick on the transmiter winds up appearing at a pin on the receiver telling the servo plugged in there to assume the same position as the stick. If its an ESC, the ESC throttle response does the same.
If the radio signal blanks out, the ESC switches off (i.e. no input, no output), servos stay put.
Enter clever radios. Depending on make, model, and instructions, you gets lots of extra features, or, as the experienced say, "extra ways to mess up". Fail safes are a good example. The generally safest for a boat is to stop the motor. With a normal boat ESC, that means either no RX output OR an RX output pulse of 1.5mS. Some modern clever RXs fail safe to what a plane ESC regards as "stop the motor", about 1mS. Unfortunately, to a boat ESC this means "go as fast as you can, backwards". Generally, ESCs just do as they are told. Some parameters can be changed if a programming card is available or if you are very good at counting beeps while reading the instruction sheet.
Not much specific help there, but hopefully enoug accuracy to help you think along the right lines until someone with specific knowlege turns up.