I wanted to start a project for this summer, linked to the sea and the pool and out of the session of the movie Aquaman, it was all found!

The idea is to make an underwater thruster in the form of jet pack (attached to the arms and legs), powerful and reliable but at the lowest cost! So bye Blue Robotics thrusters and Pelican cases, here it's cheap.

I did not have a lot of time in front of me so, the goal is to simplify the task, I have spend a lot of time to obtain directly on the internet the majority of components I needed. So those who like me, want to realize this project but have not much time to devote to it will be very happy. Some others, and I understand totally, prefer to spend long hours to design and make their own parts, that's even better !

Supplies

So for the list a supplies we have to main components

The thrusters
1. The best choice at the moment to get great cheap thrusters is to buy this unit by rovthruster.com
  They did a great job designing a very efficient thruster (up to 4.78kg of thrust and efficiency of 52 g/w) all in strong and durable plastic. They are also responsible for the great carbon tape from carbonheater.us ;)
  40$ each (shipping inclded) from rovthruster.com, Ebay or Amazon
2. DT700 brushless motor
  From HobbyKing or Aliexpress
3. Some low viscosity epoxy to protect motors from corrosion (especially in salt water)
4. 16 AWG wires
5. Heat-shrink tubes and insulated braid / PET sleeving
6. Custom 3d printed arm mounts
  File avaliable on Thingiverse
The control box and remote control
1. As the waterproof box I have choose one from Decathlon fishing products
2. Two brushless ESC (I have two 70A RedBrick ESC from Aliexpress, you will need at least 30A ESC)
3. Two waterproof connectors to connect the thrusters to the control box
4. Some 3S Lipo batteries (I have two 5000mAh 20C from HobbyKing, they fit perfectly into the waterproof box)
5. Two XT60 female connectors for connecting the ESC wires to the Lipo battery (if your batteries have XT60 connectors)
6. A remote control, I have used a wireless waterproof remote control designed for electric foil and skateboard.

That's it, a budget around 150$

Knowing that you have some options, taking a wired remote, switching from Lipo batteries to GEL / AGM lead acid waterproof batteries. Feel free to adapt this tutorial.

Step 1: Build the Thrusters

What you will need for this step (all details in supplies list)

Thrusters nozzles from rovthruster.com
(Very efficient thruster, up to 4.78kg of thrust and efficiency of 52 g/w)
Two DT700 brushless motors
Low viscosity, heat conductive epoxy to protect motors from corrosion (especially in salt water
16 AWG wires
Heat-shrink tubes and insulated braid / PET sleeving
Two custom 3d printed arm mounts
Two 3 poles waterproof connectors

Very simple to build,

Poor some epoxy into the disassembled brushless motors to protect the wires from water.
Follow the guide given by rovthruster to put together the nozzle, motor and propeller.
Solder to the three motor's wires 1m of 16AWG cable and protect the solder with heat-shrink tubes.
cover the wires with the insulated braid / PET sleeving.
Solder at the end of the wires the three poles of the males waterproofs connectors.
Screw the thruster to the arm mount.

Repeat the operation for the second thruster.

Step 2: Prepare the Waterproof Control Box

What you will need for this step (all details in supplies list)

A waterproof box
Two ESC
Two female waterproof connectors
At lease one 3S Lipo battery
Two XT60 female connectors for connecting the ESC wires to the Lipo battery
A remote control

Drill two holes of 21mm inside the middle section of the box
Place the two female waterproof connectors and check that the rubber joints are well positioned and squished enough.
Solder wires from the connectors to the ESC
Solder the XT60 female connectors to the ESC
Plug the receiver of the remote to the ESC

You are all set :)