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Making a waterproof USB 3 cable

Hi guys,
I need to make a waterproof USB 3 cable with Blue Robotics penetrators on each side (optionally a subsea connector on one side).

I was thinking of using a 10 core PUR cable and solder on an usb C male PCB kit on the inside of side A, and a standard USB 3 on the inside of the enclosure on side B.

Side A:

Has anyone done this kind of custom cables before? Will it be problematic getting real USB 3 speeds?
Any input on cable choice?

Cable option:

Lapp Olflex Servo FD 798 CP 10 Core CY Control Cable 0.25 mm², 0.5 mm²


It would be nice to use the Fathom cable, but it is only 8 core.


I don’t know about long-term subsea use, and how it compares to the polyurethane jacket you’re considering, but L-Com sells high-flex USB-3.0 cables with a thermoplastic elastomer jacket:

I bought some for this purpose (connecting an external camera through BR penetrators) and it seems pretty tough and flexible, but I haven’t pressure tested it to any substantial depth yet.

USB 3 has a bunch of shielded twisted pairs for tight electrical impedance control. If you’re going to need full USB 3 speed I’d expect you’ll run into problems if you don’t use real USB 3 cable, but I haven’t tried it. The shorter the better if it’s not properly constructed cable.

Maybe some usb 3.0 over ethernet adapters inside the device at each and and then just use the Fathom tether?