Ethernet tether

[Octonaught1]

Hi everyone,

I am in the design/prototype phase for my rov. I intend to use ethernet cable down to 100m if I can, but I have the following concerns about it:

1) Twisting. Has anyone encountered problems with the cable getting twisted
2) Bouyancy. Would having up to 100m of cat6 cable above the sub might affect the subs bouyancy characteristics at depth?

I did a search and there are companies spruiking bouyancy neutral and ruggedised cat5 cable. Has anyone tried this?

[thegadgetguy]

If by twisting, you mean the entire cable being twisted as the ROV rotates, you just have to make sure that you try to make as many turns in one direction as the other. If you mean how strong is the ethernet cable in regard to twisting (as mentioned above), you will probably not have a problem with twisting if you plan to run anywhere close 100m of tether, unless you turn a lot.

In regards to bouyancy, you will need to attach floats periodacly to the cable(or buy a comercial tether that is nuetrally bouyant) so that your tether doesn't pool on the bottom and keep your ROV from moving.

Good luck and welcome to the forum.

[Octonaught1]

Thanks Gadgetguy,

I am also toying with the idea of using power over ethernet (POE) for some of the onboard devices like the camera for example. Has anyone played with poe yet?

I have found a 48v 4 port poe switch I am thinking of putting into the sub with probablya stepdown transformer for the 12v devices. Not be electronically experienced, I wonder what the drawbacks to this would be?

Either way I am going to put in an ethernet switch anyway for the camera and mainboard so I just have the one uplink cable.

[derelicte]

I use poe for the security cameras in my house. it is super convenient, but you don't get a lot of power over a single link.

the older spec only supplies 15.4w (1.28a at 12v). The newer one provides up to 25.5w (2.13a at 12v). Even with the newer spec, you won't be able to run a single thruster but it would be fine for a couple of cameras and a controller.

[Octonaught1]

Thanks derelecte,

It looks like it'll probably be a normal switch then.