Underwater Thruster, Low Power Deep Water Thruster 500KV Motor ...

1. Exquisite workmanship and materials ensures long service life and higher work efficiency.
2. Low power deep water thruster, 300M performance and workmanship.
3. High strength bearing, with and anti- function.
4. Special anti-seawater coating, which can be used in high salt and water for a long time.
5. Metal and electronic component material manufacturing ensuring maximum durability.

Specification:
Condition: Brand New
Item Type: Underwater Thruster Motor
Material: Plastic and electronic component
Color: Black
Motor Rotation: CW
Motor KV: 500KV
Maximum Power: 312W
Diameter of Axle: Approx. 3mm / 0.12in
Matching ESC: 30A
Maximum Current: 13A
Operating Voltage: 12V-24V
Standard 12V Parameters: Current 8A/ thrust 1.2kg
Maximum Speed: RPM
Diameter: Approx. 71mm / 2.8in
Length: Approx. 112mm / 4.4in
Frame Width: Approx. 43mm / 1.7in
Depth: 300 Meters
Mounting Screw Size: M4
Suitable for AUV ROV, RC Boat, deep-water submersible propeller engine

packing list:
1 x Thruster

Note:
1. Please allow 1‑3mm error due to manual measurement. Thanks for your understanding.
2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.
3. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.

If you want to learn more, please visit our website.

I know that bow thrusters don’t do much with any speed on, but like a lot of things people know I am not sure I know exactly why.
I was helping try to get a high-freeboard vessel hooked up to a mooring with no painter. I took a tender out to the mooring, tied a line to it, and stood by to hand it up. The boat came right at me and then hit the bow thruster. I could see that they had enough way on for the bow thruster water exhaust to be streaming aft, the boat didn’t change course, and I had to fend off from being rammed. We did get the line up though and all my limbs are still attached
So…the actual part of the assembly that pushes the bow I think would be the prop thrust in the tunnel. If the prop was loose it would tear itself off the shaft and depart, wouldn’t it? Why does it care where the water goes next?
It clearly does though, every vessel has a speed beyond which the bow thruster is just wasting electricity. I used to install the things and warned the owners about this, but I can’t quite get exactly why offhand?

Most thruster tunnels I’ve seen have a deflecting bump on the outer edge at the front to guide waterflow past the tunnel when underway to reduce the effect of the water colliding against the trailing surface of the tunnel. I worked on one yacht where the owner would demonstrate his marginal helming abilities by traveling at excessive speed in a harbor and using the thruster. The result was a lot of increased noise and cavitation from the thruster with little effect, other than everyone in the harbor swiveling their heads towards the racket.
I believe the physics is that the propeller “screws” itself in one direction or the other, with the actual reactive force being on the propeller and all it’s supported by. If it’s cavitating, it’s acting more on a gas than a liquid.

May be this?

If a water stream crosses a perpendicular opening, (even water in a pipe if it passes a lateral and pressure less bifurcation) it will create suction in the bifurcation; the higher the speed of the water flow, the higher the suction force in the bifurcation.

Link to Haoye

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The thruster’s tunnel is just such a bifurcation… on both sides of the ship. Beyond a certain speed of the ship, the thruster may not be able to overcome the suction forces.

A bow thruster is most efficient when a vessel is stopped because basically it is a clean flow of water and clean flow out of the thruster. When moving ahead or astern , the flow of water across the bow thruster tunnel causes the flow to reduce and become less efficient.

Moving above say 5 or 6 knots ahead or astern ( less with a weak thruster) the thruster becomes completely inefficient and not effective at all.

A bow thruster is most effective when moving astern. You can imagine for practical purposes it is the long lever from the bow thruster to the pivot point moving aft but is actually the hydrodynamic effect of water on the moving vessel.

yep the bump is there for 2 reasons, to mitigate resistance while the vessel is going forward under standard operation and to allow for clean water without bubble/resistance while going at slower speeds when thruster is in operation. Propellers are designed to operate fully submerged so the bubble create cavitation and cavitation is not good for efficiency
On a bow thruster they are evenly balance to have equal amounts of thrust depending on which way they are turning, screw analogy works
Generally speaking you will not see bow or stern thruster tunnel much longer than 6x the diameter of the thrusters propeller as that is generally the size that efficiency completely falls off
Research vessels often have water jets in lieu of tunnel thrusters to allow for thrust underway

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