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My favorite R/C vehicle is actually... Boats! Most of my R/C boats were very slow and had a very bad radio system. Then, I made my homemade Jet Boat, that was very cool and I did a video about it:

But the motor was a brushed one, so the lipo battery (11.1V) fried it.

Later on, I searched on youtube about brushless motors and found that they are INSANELY GOOD. So, I decided to build a brushless R/C boat myself for an reasonable cheap price. It worked well for a while, the motor burned and this project is still in progress...

Here's the video:

Step 1: Gaining the Materials...

First I bought the Fiberglass hull, that was at a good price (because I don't know how to build a professional hull).

Then the electronics:

-A watercooled brushless motor from banggood - 4000Kv, up to 4S, 4-pole, 15A Max, inrunner.

-The watercooled hobbyking 30A ESC that holds up to 4S and has a BEC voltage of 5V.

-The hobbyking waterproof servo (HK-15269)

-A turnigy 3S battery of 2200Mah.

-The the hk 3100 receiver with a turnigy 3XS radio.

Step 2: Shaft, Prop & Rudder

I found a old large R/C boat that contained two shafts with self-tightening counter-rotating props. It also contained the apropriate stuffing tubes.

For the rudder, I found some lego pieces and a flat rectangular part of a box. I hot-glued them together in the back side of the boat. Then I connected the servo push-rod at the rudder's arm.

Later I used again lego pieces to make a holder for the water pick-up located at the front of the prop.

Step 3: Motor Mount and Coupler

For the motor, I built a metal support and glued it on the hull with heavy duty epoxy (since the motor can vibrate a lot).

Then, I found those wire terminal blocks and removed the plastic case arount it. It was used as a motor coupler.

Step 4: Installing Electronics

I installed everything with hot glue on the boat. The battery was held by a velcro strap.

Then, I drilled two holes on the sides to fit the two indicator leds (red-left and green-right).

Step 5: Watercooling System

For the watercooling, I used small and long tubes that are in the following order:

Water pick-up (mentioned earlier) > Motor > ESC > Out

Step 6: Test Run

I got some problems... The rudder was too small to turn the boat and the motor overheated too much. Because of the watercooling sequence, the water wen to the motor, got very hot and then overheating the esc. one day, the motor bursted into flames. When I took the boat off the water and opening the hatch, all I could see was smoke.

Step 7: Upgrade!

I went on HobbyKing searching for a new motor and I found one that should work. It's the Turnigy Aquastar 2842-2800Kv. I ordered it (+ an 50A esc because the motor is 40A) and while that, I upgraded the rudder with a 3D printed one.

Step 8: Arrived!

About 1 week later, the electronics arrived. I then connected the bullet connectors (everything comes pre-soldered!) then, turned on the transmitter, connected the battery and calibrated:

battery connected > BEEP BEEP > full throttle > BEEP BEEP ... BEEP PEEP > calibrated.

When turning on normally, it goes: BEEP BEEP ... BEEP BEEP. I turned on and it sounded like a jet engine! (because of cooling fan) After a continuous 1/3 trottle, anything heated! Is a very good power system!

Links down below:

Brushless motor at hobbyking

ESC at hobbyking

Step 9: Motor Mount

I found some old building toys that contained metal and did another motor mount with it. I also used a screw mounting adapter.

<p>I looked over your setup from your pictures and your rudder seems to be installed too high on the transom. It looks like very little rubber actually in the water and therefore you can't get much out of it in turns. Take a straight flat edge and place against the bottom of the hull to see how much rudder is extending below the bottom of the hull. Also, boats have a tendency to want to turn to one side more then the other (like aircraft as well) because of the rotation of the prop. It also looks like your stuffing box is not fitted properly. The diameter of the actual draft shaft seem to be too lose in the casing. Is that the actual stuffing box setup for that boat? And it looks like you have a slight angle issue between the motor output shaft and the stuffing box and drive shaft. Any little misalignment takes away from the power and speed output and causes vibrations. And finally, don't give up, stay with it and you will gain lots of knowledge and fun once it is setup properly. Thumbs up!</p>
<p>Oh, sorry, in the pictures the brass bushing fell off, but now it's re-installed. Part 2 is already in progress and I fixed the vibration issues from the shaft, using a wood block to hold it in place. Because the motor didn't fitted in the old motor mount, I built one with metal pieces from old building toys, screws and nuts. As I mentioned, I upgraded with a new rudder that at the end turned the boat really well. I faced a new problem at the moment: when I get the boat in plane, it wanted to dive in the water, maybe putting some foam at the front may help! Thanks for your feedback!</p>
<p>I am not sure what you mean with the boat wanting to dive into the water when you get it on plane. Adding anything to the front isn't going to fix that issue. And I really have no idea what you are talking about with adding foam. IDK. Usually a dive points to the angle of the prop to the transom. But I can't see how you could easily change that without some additional parts. Post some more pictures.</p>
<p>Actually, the shaft is very angled down, because I'm having prop height issues.</p><p>The prop is too high in relation to the water, it's sucking too much air and providing low thrust even at high RPM.</p>
<p>Following your feedback, I angled the shaft straight, in a way that the prop is still in the water, now it works great and turns very well! Thanks!</p>

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