Hell of a Christmas ....

[Magic1]

My real name is John Kent, although most of my life I have been called Magic. My wife died over Christmas (27th) and an ROV was one of the ways of coping with that. Why build an ROV ?. Well, Britain is a cold and miserable place in the winter and if I was going to use an ROV it would have to be in the Med. Sparkling clear seas, sandy bottoms, lots of brilliant sunshine and I guess that coloured my thinking.

At the moment there is a pile of 21mm pipe and fittings here in my lounge in UK, one 5 bladed Graupner 40mm prop and one 1100 pump on the way from China (not a Rule).

Gut feelings. I get the feeling that I need to control the vertical motors with PWM and that rules out relays and means H bridges. Initially I did not feel that a single 1100 pump had enough vertical lift, to use an arm for other than very small objects and insufficient for a reasonable rate of climb from any depth .... even if I switched from the 5 bladed 40mm Graupner prop to a three bladed 50mm Graupner prop. In the Med, we do not have the same sedimentation problem as in lakes and some rivers, so it may make sense to go for thrust, over disturbance of sediment on the bottom. With PWM I can control the overall current drawn from the surface to suit the actual need.

I side thought is that it would be reasonable to expect the need of a very large ROV to lift heavy loads. I now don't agree with that, so it leads to me looking at the manipuation arm in a different way.

It will also be interesting to see what can be done in fitting a a small ROV with metal detection , air lifts and magnetometers.

[scubersteve]

I know it may not mean much from a faceless stranger half a world away, but I am sorry for your loss.
On a hopefully happier note, welcome to the forum.
I agree with your evaluation that proportional control is preferrable especially for the vertical thruster. I don't know how else precise depth control could be easily achieved. It sounds like you have an ambitious design in mind. Please post plenty of pictures as you progress.

[rossrov]

The kindest gestures often come from total strangers. This hobby and forum can certainly keep one busy Welcome.