Tether buoyancy idea.

[Pilikia]

Paul ~ Thank you for your answer. I like that the video doesn't need coax.

When you say, "... I only have one or two cables ...", does that mean you are using onboard batteries for primary power? If so, what batteries are you planning to use?

[PaulC]

I am actually using a topside battery. When I say that I am using one or two cables I mean that I was using one cat5e cable for control and power, and was using another cable for video. I know that most people use a cat5e for control, separate for power and video, but in my opinion that makes the cable way to bulky. Now on the new rov I am going to use 2 cat5e for everything.

[PaulC]

I meant most people I think are running separate power along side the cat5e.

[Pilikia]

Paul ~ I see Steve has quietly added something interesting in his "How To" pages:

http://www.homebuiltrovs.com/howtotethe ... edrop.html

It's weird, the Forum software refuses to print the entire address. But the link does work. Check it out.

[PaulC]

Thanks Pilikia I also must note that if you look at Steve's Sea Fox retrofit. Look at how he set up his tether. Like I said earlier it seems that most are using separate power for the ROV.

[sthone]

I think what Pilikia is referring to with my link is the fact that cat5 really can't handle the power requirements needed to power thrusters, which is why most people run a separate thicker main power wire to the Rov.

Running a separate power feed will make the tether more bulky but there just no way around the voltage drop while sending power over the tether. (unless you do use on board batteries)

-Steve

[PaulC]

Hey Steve
How did you run power down to the terminal blocks on your first Sea Fox before the retro fit, and how did you tie that all in with the phone cable for control? The reason that I am asking is because I am using terminal blocks instead of relays at least for now.

[sthone]

On the original Seafox I sent the power down to each thruster through a doubled up pair of phone wires, (4 wires per thruster) my results were meager at best. (even over only a 50' tether.) I really didn't understand voltage drop back then. The terminal blocks where just a means to attach the tether wires to the thruster wires. The pumps were so under powered the only reason it worked at all was because of such a short tether and I would only use the Rov directly under the boat so it really didn't have to drag the tether around much. If I tried to use it from shore with floats on the tether to keep it off the bottom the wind would blow the tether around (from the floats) and just drag the Rov with it, it was that underpowered.

I wouldn't even waste your time trying to do this as the voltage drop is huge. If you look at the results from my testing on this page http://www.homebuiltrovs.com/howtotethe ... edrop.html you will see that starting with 12 volts over 100 feet of cat5 the thruster only put out about a 1/10 of a pound of thrust.

It's still not the perfect method but a simple relay setup is probably the easiest way to start.

-Steve

[PaulC]

Thanks for the tip Steve I think that on my new ROV I am going to try relays.

[bigbellydude]

Has anyone ever considered using Styrofoam as a buoyant? I would think that it wouldn't compress at further depths because of its rigidity. I don't have any experience with this yet, but my MATE team is considering using it for our floats.