Tethers at high depth(beyond 1000ft)



I read this on Video Ray’s website,
"For shallow dives, any of the neutrally buoyant tethers will suffice while a combination of negative and neutral is usually employed for deep dives down to 305 m (1,000 ft)."
Can anyone please explain why we should use a combination of tethers at high depth and how to determine the combination?


Great question!

For deep applications, a negative tether can be used to for the distance between the surface and the operating depth, and a neutrally buoyant tether can be used between the bottom of the negative tether and the ROV so that the ROV can move freely. This combination of negative and neutral tethers at greater depths is often used to keep the ROV from having to pull an entire length of tether behind it as it moves, and to save cost since neutrally buoyant tether (especially the kind that can stay neutrally buoyant at those depths) can be very expensive.

A clump weight is also often used at the interface between the two tether types so that the negative tether stays relatively vertical and acts less like a spring which could pull the ROV back from the direction it goes. The negative tether should be long enough to get to the expected operating depth, and the neutral tether should be long enough for the radius it prescribes around the clump weight is sufficient for the mission.

Incidentally, you can see a fun video of our first experimentation with a clump weight and gripper arm here.

Hope this helps, and good luck with your project!


Manufacturing a shell for deep dives at 1000m+

Thanks a lot Eric. Great explanation.


I suggest to have a look on xingtera adapters

coax for long distance is my recommandation

G.hn an Powerline 200 is the same technology … just G.hn is ITU standard and Powerline Qualcomm proprietary stuff