This Kort nozzle designed for DT700/750 motors. We use them in 2 our ROVs. They are about 15kg weight because of 12v leed batteries onboard so we limited current to 5A maximum to have long run time. It gives enough speed and thrust to help our divers even if they ask to bring a spare scuba tank. We also use them for small trolling boats, two motors at 10A each one give 5-6 km/h.

We never use them at 20A cause big current means very short battery run time.

If you will use them at high power you should prepare DT700 for it. Our test show this two small screws can not keep the motor from turning at maximum load.  Even if you screw them hard they cannot make a good hole. This can lead to a break in the wires and damage to the motor.


I recommend you to drill a sink:


Ring with 3 nuts  can be set only this way:


Insert 3 wire through the hole:



Then insert motor shaft in to holder. Make sure that all three wires are laid exactly opposite the hole:


Insert the motor as far as it will go into the holder:



Insert your hex key from DT700 kit in to hole and fix 2 set screws:



Now gently screw the cone nozzle onto the shaft. Tighten it to the stop with a little effort:

The nozzle does not give much traction, but protects the motor wires from damage.



Screw the propeller on the shaft until it stops but do not over tighten  then fix it with nut:



DT700 can work underwater as it is but after a few hours wire will corrode even through protective lacquer.

To prevent corrosion you should epoxy it.

1. Remove lock washer


2. Pull out stator from rotor


3. Wrap with kapton tape


4. Cut a circle with a diameter of 35 mm from a thin transparent plastic (for example from a blister pack)...


5. ... and stick it with a piece of plasticine to the stator.


6. Wrap it with kapton tape.


7. Prepare epoxy. Choose an epoxy with a low viscosity and a long hardening time. To reduce viscosity you can preheat the epoxy.

 This will help fill all the gaps between the wires and leave as few air bubbles as possible.


8. Pour epoxy slowly with a syringe. This will give time for the air to escape without the formation of bubbles.

For the best result you should vacuum it:



9. When the epoxy hardens remove the kapton tape.

If necessary, grind the edge of the epoxy with a nail file.


The DT700 motors have stainless steel ball bearings and they not afraid of fresh water. After working in salt water, it is NEEDED to rinse the motors with fresh water.

The DT700 motor is very effective for the thruster because of the long axis, which allowed the motor to be moved beyond the tip of the nozzle. But the long axis leads to a rapid wear of the bearings and the appearance of play. At our robot motors worked without repair for 2 years and during this time the backlash reached 5mm! The motors at the same time continued to work but the efficiency decreased and there was a strong noise. For best results, we recommend that you replace the ball bearings with porous bearings self lubricating bronze 4x8x3mm.

Using the motor shaft, push out the old bearings.


Replace two ball bearings with two bronze.


Compatible motors

hexTronik DT700






hexTronik DT750:






Volantex 4023 Brushless Motor 850:






Required shaft replacement: