Introduction and personal background info

[RDTwigg1]

Hello from the Pacific NW:

I am currently retired and looking to build my first ROV. I was a systems design engineer with Honeywell Marine Systems. I also had my own Consulting engineering firm with ~19 employees. With Honeywell I designed sonar systems for ROV tracking and acoustic drill rig positioning in deep water. Also worked on 'other' dark projects for the government. I got interested in ROV's when I was in the North Sea with the HarborBranch folks. They were having problems with their ROV and preventing the project from getting underway. So I helped them to get it going and I became hooked. My goal will be to design a wireless Semi-autonomous ROV for shallow water (<100ft) inspection and repair. I will be using a Beagleblack CPU with additional peripherals. I may need some UNIX assistance so I have joined this forum for support in that arena.

[RDTwigg1]

My preliminary thoughts are that I want to increase efficiencies wherever I can. A couple things I want do to is reduce the IR drop in the cable or eliminate the cable altogether. The second thing I want to do is improve the water flow around the prop to get the most power efficiency in the water column past the blades. I think I can do two things here. First, I can eliminate the wash off the blades with a lightweight prop shroud. To improve thrust I believe (without proof) that I can place two props on a single shaft. This will probably double the load and decrease prop speed. I do not know if there is any cavitation going on at higher speeds but if there is, a dual prop will both reduce the maximum speed of the prop, thus reducing any shallow water cavitation, while increasing the water flow (thrust) at lower speeds.

Any thoughts here would be appreciated.

To eliminate the cable I am thinking of 100% battery operation. This will undoubtably limit my submerged time. But the increased local efficiencies to the motors with very little IR drop and overall system improvements like adjustable ballast, LED lighting, isolated supplies, etc should give me plenty of time to do shallow water inspections.

Eliminating the power cable would mean a wireless communication scheme. I'm thinking of a tethered antenna float on a constant tension reel. Alternatively there are acoustic techniques I could use the minimize reverberation and noise interferences.

Anyone out there with any experience on having tried these ideas?

[rossrov]

Welcome RDTwigg1. The floating antenna on a reel thing or similar is something I want to try one day. Acoustic control and low bandwidth comms sounds interesting if that's what your'e referring to, but what about the video - though you may have something else in mind? Anyway, sounds like you've found a good forum!

Ross

[RDTwigg1]

Here is my first conceptualization of the ROV. I have not tried to attach a PDF here so this might fail:

[scubersteve]

I keep thinking a counter-rotating dual prop on a single shaft setup would help with efficiency.
I know it was a big deal when the "Bravo" outdrive came out for boats.

[RDTwigg1]

Good to know - I don't know how to implement it but I will check it out. My thought was to have a small sump pump blade in combination with a propeller type blade going in the same direction. I might try that to see if it works. Might be too much turbulance at the blade to be efficient. - Don't know.

Included a thruster concept (page 2) which would probably load down the motors, but increase thrust. Might be a waist of time. - Any thruster experts?

The main outer cylindrical frame makes the whole assembly rather robust and configuration flexible. I might punch some strategic holes in it to lower overall weight. Strateigic cutouts might be needed to reduce the sail area on each side.

[martinw]

Looks quite similar to this one, which sells, so it must be a good concept ....

http://www.jwfishers.com/rov.htm

Martin

[kenl]

The Sealion design is what I'm aiming for, I hope to improve on it

[RDTwigg1]

Made a few changes to the initial concept - moved the thrusters fwd/rev to the outside of the housing. I will angle these two thrusters to the inside by about 5 - 8 degrees to reduce turn radius. I may initially have a 1/2 inch thick clear flat plexiglass instead of a dome. I added a couple aluminum bumpers to protect the thrusters.