Foam for tether jacket

Hi there,

Currently working on making my own neutrally buoyant tether for my ROV build. I’ve spent quite a while looking into this but can’t seem to find specific details on which closed-cell polyurethane foam is well suited for neutrally buoyant jacket for the tether (perhaps unsurprisingly). Has anyone found any hints or useful information on this? The tether length is in the range of 100-200m.

Many thanks,


Hi Russ,

Can you give a little more detail on your design? Due to the difficulty in design, drag effects, power requirements, tether design can be challenging. The kevlar lined tethers used by Sofar and BlueRobotics are the cheapest and easiest to use. Yes, this is a COTS solution, but given how, at 200m, tether drag is going to highly affect ROV control, negatively, plus tensile load requirements. All this needs to be factored into the design with NB as an additional parameter. I looked at this a few years ago and decided that a COTS solution was best, lol. But don’t take that as a bash against designing your own. Post your design or general idea and we may be able to help.