Underwater Ethernet

This isn’t security related but nonetheless is a good story about how it can be useful to attack a problem in an unusual way. Sometimes the result is suboptimal, but often by thinking “outside the box” you can chance upon a solution that is simple and cost effective.

A few years ago a client gave us a somewhat unusual design brief. He owned a large rural property which featured a lake which provided fresh water recreation. He also had some log cabins on site and leased these out to vacationers and for school camps. Recently he has been diversifying into offering executive “weekend workshops” which appear to have become somewhat of a trend. I believe that large corporations send a team of employees away for a weekend of “trust building” exercises all mixed in with a few conferences. As pointless an exercise as this may be, it has been a great little additional income stream for the property owner. There was just one small problem.

A large corporation wanted to make these weekends a regular thing but complained that there was no cellular coverage and no Internet access available within the rooms. Which is kind of the point of a rural retreat, but nonetheless – the customer is always right. So we set about rectifying the situation. Cellular coverage wasn’t a major bone of contention, so we didn’t try and rectify this issue (the client was so far away from civilization that a picocell running over IP would be the only potential solution. That said I believe that the latency of satellite would make voice calls frustrating).

The owner had satellite Internet available in his home (about half a mile away on the same property) which was installed on the cheap several years ago thanks to a state subsidy program that has since been disbanded. He approached me with the idea of using wireless to somehow get the signal to the cabins.

Unfortunately the property has very undulating terrain and there are dense tall trees blocking the line of sight. No doubt we could have snuck a repeater somewhere – or even used a wireless mesh, but I felt it wasn’t the way to go. There appeared an obvious way forward.

The homestead was just 20′ away from a channel that fed water from a small river that fed his lake. The river flowed all year round and the small creek was also supplemented by a bore that pumped into the creek. The log cabins were all centered around the shore of the lake where he’d placed sand to make a beach like foreshore area.

So we purchased a reel of armored Ethernet. This fantastic stuff is designed for direct burial and is basically a heavy duty Ethernet cable covered with a metal cladding to keep your cable safe. We then purchased an obscene amount of “bituminous butyl tape” which looks and feels like cloth tape soaked in tar and set out with the boat.

We ran up along a small wooden boardwalk near the homestead and cable tied it along a PVC water pipe, then dug a small ditch and got the cabling to the homestead end.

The night before we begun we got a collection of beer cans, opened the top with a can opener and filled them with concrete. We embedded an eyelet into the concrete of each can. By morning we had our own homebrewed weight system.

As we motored along the center of the creek we attached a weight every 8′ or so with cable ties and dumped the cable into the center of the creek. When we reached the lake we went in a diagonal to a small wooden pier in relatively deep water. We took it right under the pier and brought it up the 8′ pole, where it went into an outdoor AP which fed two patch antennas. All of the log cabins had adequate reception and no repeaters or WDS arrangement was required. Despite the distance the PoE worked as advertised and the Ethernet functioned well. Perhaps it is due to our choice of cat6 cable despite not requiring 1000base.

I checked back with the owner a few months after installation and it is still operating just fine. Sometimes it pays to think outside the box.