I just thought I’d share my build now.
Finally came round to potting those subcons, not the greatest pot, but it should do the job.
I also found a Gardena reel, on which the 200m thether fits nicely. I may find it a bit small in the long term.
The slip ring is in and ready to interface to the Fathom X, just need to find or make a good enclosure.
The idea here is to use a Hootoo Titan Tripmate to power the Fathom X at the surface, and use the access point facility to make it wireless, so the Ground control laptop is not tethered to the reel, giving us a bit more flexibility in the setup.
Any (constructive) comments are welcome