Selecting a Waterproof BLDC Motor for Electric Surfboard

I am a final-year student studying Electronics & Computer engineering at Camosun College in Victoria, BC, Canada. I am a part of a group of three working on creating an electric surfboard for our final capstone project that we will be working on this fall. At the end of the term, we will showcase our project in front of hundreds of people at the capstone presentation event so some marketing material would be beneficial to us both (stickers, flyers, etc).
The plan is to design, prototype, and construct both the electronic components (motors, battery packs, ESC, and various other controls) and the hull of the surfboard.
We have been looking around for a reasonably powerful BLDC motor that we could use to power the board. Our goal was to achieve a top speed of around 30kph to 40kph and we estimate that we would need about 6kW of power to achieve our target speed. This is based on values found in other commercial electric surfboards that are available.
We are currently looking at either using two ATO-BLDC-WP3000 model motors or one ATO-BLDC-WP6000. Which one would you recommend for our use case? Also, seeing as we are planning on making our own ESC for the motor, do they come with a hall effect sensor package built in? If not, how does your recommended ESC know the position of the poles, etc.? Does it use back EMF to find the poles?

Tambor wrote:
We recommend using the ATO-BLDC-WP6000. The motor doesn't have a built-in Hall Effect sensor, and the ESC uses the back EMF to find the magnetic pole.

If you're targeting 6000W, using a single ATO-BLDC-WP6000 makes more sense. One motor simplifies the mechanical design, reduces synchronization issues, and requires fewer components (e.g., one ESC instead of two). You’ll also have less weight and drag in the water.
As for position sensing, most high-power BLDC motors don’t include built-in Hall sensors. Many ESCs, especially sensorless types, rely on back EMF to detect rotor positions. If you're designing your own ESC, you'll need to ensure it can handle sensorless operation smoothly.

Based on your needs, I recommend using ATO-BLDC-WP6000 directly because:
It is simpler to use a 6kW motor directly, and there is no need to consider the synchronous control of two 3kW motors and additional mechanical structures.