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Help with ROV building!

(Luis Gamez) #1

Hello guys,

its me again, as said before I am trying to build an ROV for 100 meters

I want to build azimuth propellers, for that i am using a stepper motor with titanium Magnetic coupling, this is great for watertight but here I have a problem

if we go under 100 meters subsea, we have 11 atm of pressure if we go to formula:

P=pgh F=P*S

p=sea water 1030
g= gravity 9.8
h= 100 meters

P= 1,009,400 Pa

if F=P*S
S= my propeller lenght

F=1,009,400Pa * .2meters
F= 201,880 Newtons!!

so the sae is giving 201K newtons force to my building, how much Torque do i need on my stepper motor to move my azimuth propeller?? or am I doing anything wrong here??

please i need help

(Harold Scadden) #2

@Luis - you are freaking out over nothing. Your rig will experience the pressure overall. It doesn’t matter if you are at 1 meter or 100 meters … the prop is still going to turn. Your problem is you are looking at water depth as something that is going to provide resistance against the prop turning … it is not. A fluid is a fluid is a fluid … your device just has to handle the pressure and the T100/200 motors themselves will handle that pressure all day long.


(Rusty) #3


The stepper motor will just have to deal with the friction of rotating the azimuth mount. That could change a bit with depth, especially if the materials compress, but for the most part, you won’t have to worry about pressure. The important part will be sealing the stepper motor so that water stays out of it.