Homebuilt ROVs Forum

Has anyone experimented with running your tether wiring inside a flexible tube, such as 1/4" air hose? Or are you running you wires directly in the water?

A 1/4" pneumatic hose sounds like a pretty small diameter hose to be running cables in. Plus it would probably be a real pain to have to push a bunch of wires through any length of pneumatic hose long enough to be a useful tether.

For the Purdue ROV, we needed a 100' tether, and it contained: 2, 10 AWG conductors for power; 1, burial grade Ethernet cable for comm. and video; 2, pneumatic hoses for the supply and exhaust, and a bunch of small strips of home insulation foam that we used for buoyancy along the length of the tether. Then we wrapped the entire thing in that woven wire wrap or snake skin. I forget the proper name for the stuff. All in all, it was about 3/4" to 1" in diameter.

To answer your question though, all of the wires were exposed to the water, and as long as there is little damage to the insulation, you should not have an issue.

I'm using 1/4" ID polypropelene air hose (3/8"OD). I used a vacuum on one end and an air hose blowing in the other to get a thread with a BB sized piece of foam tied to it through it. Pulling the hose out straight and silicon spray helps a lot along with shaking and wiggling the hose around to help the thread pull/blow through. After the thread is through I pulled a stronger nylon mason line through...then the wires. I found that 4 pair (cat six cable with the outer covering stripped off) plus one 24 ga wire makes the tether very slightly positive bouyant.

We did the same. Used a vacuum on one end, and poured soapy water behind the small wad of paper tied to the string. Next we tied the 100 foot wire bundle (2 power wires and 3 pairs of cat-5 wire.... TX/RX, video, and a spare set) to the string and pulled them through.... pouring soapy water in the tube to keep the wires moving.

Jim

This system has been used on commercial ROV in the past, ie, workable.

using the vacuum/ string technique is the best way to do that.

using ceiling grid string is a good idea.

putting vaseline on the paper or foam serves a dual purpose: lubrication/stronger grab by airflow.

At work we tow a sonar array ,behind an AUV, that is flexible plastic tube with the wiring pulled through under vaccum and then filled with a parrafin like oil at 4 bar to make it neutrally bouyant. i'm sure we could do something similar at home. very messy but do-able.
P.S.- Quote: "I forget the proper name for the stuff." We call it Nomex. but there's all sorts of names for it.

I was thinking the same way but it was out of question as I decided to use a fiber optic tether. I made before some experiments how to get the wire through the hose and final solution was to use a ball (pearl in my case) that fits just into the hose. I took my fishing rod and attached the braided line to the pearl. Then I went to the fuel station with the coiled hose and used the air to put pressure on the car tires and was shooting the pearl in seconds through the entire hose, so the hose was prepared. But as I said, i didn't use the hose, pulled the line back out and returned the hose to the store to claim my money back