Waterproofing Cable Entry Points: Ethernet, Power, and SMA RF Connectors for BlueBoat Integration

Blue Robotics Vehicles BlueBoat
1

Hi everyone,

I’m integrating several devices onto my BlueBoat platform, including:

  • Jetson Orin NX
  • OAK-D stereo camera
  • Ouster OS1-32 LiDAR
  • ArduSimple simpleRTK3B compass module

I need to route the following through the hull:

  • 1× power cable
  • 1× Ethernet cable
  • 2× RF cables (SMA connectors for GPS antennas)

My main challenge is figuring out how to waterproof the cable entry points—where these cables pass through the hull/junction box.

I’m a complete newbie at waterproofing, so I’d love any advice. For the power cable, I assume a WetLink connector works well. But:

  • How do you waterproof Ethernet (RJ45) and SMA RF connections at the entry point?
  • Are there bulkhead connectors or pass-through glands that don’t require me to cut/re-terminate the cables?

If anyone has experience or product recommendations for waterproofing these kinds of entry points, I’d really appreciate it. Thanks so much!

2

Hi @andycyl -
Cutting the connectors off, passing the cable through an appropriately sized WetLink penetrator, and re-terminating is likely the best bet for a reliable seal. While bulkhead ethernet connector options are out there, in my experience they don’t remain leak tight for very long. The product page has extensive guides to help you select and use this solution.

When it comes to your RTK GPS, we’ve had success simply mounting the antennas under the deck, on the stern and bow side of the starboard/port hull - that makes routing the co-ax into the hull unnecessary! Otherwise, WetLink Penetrators, when used with coax cable, usually need to be drilled out to eliminate the internal step. By drilling the ID out to the OD of the coax cable, you can pass the cable through without having to remove the outer jacket, and re-terminate the connector. This does compromise the depth rating, but only at extreme pressures - your BlueBoat won’t be going below 40-100m!

3

Couple input points on the SMA connector.

I’ve not found one of the BR WetLink penetrators small enough for RG-178 coax which is around 1.8mm od. So, I’ve experimented with the following approaches:

  1. using the blue robotics potted cable penetrator. I pot a bulkhead sma using marine epoxy and make sure it flows down the stem. This has worked for me most of the time but I have found some SMA providers have SMA connectors that actually leak through the center connector. I’ve had good success with Gradcon (now GCT) type connectors which apparently seal that center conductor. I’m actually using a gradcon/GCT connector wihtout the pot mounted directly on a 6mm hole in a endcap coupled with the o-ring flange.

  2. I’ve considered moving away from SMA and going with the more robust TNC connectors. I need u.fl connection to my electronics on the inside of the enclosure.

So far, I’ve had successful pressure tests with one version of #1 and another with the Gradcon/GST directly through an endcap (without the pot).

My application is for an external wifi antenna running about 50ft back to the surface.

4

Hi @Lprevost -

Another approach for using a WetLink Penetrator with a smaller cable is to increase the diameter of the cable with one or more layers of heatshrink (with internal glue) present. If you get it up to a size for the penetrator, and compress the seal on to this thicker portion, it is typically fine, although certainly not to the standard 1000m depth rating. If you’re going 100m or less I wouldn’t anticipate any issues, beyond that you’d want to test!