The Anchorage is a bay off Tanera Mor in the Summer Isles, in North-west Scotland. After swimming in this water for a few consecutive days and being quite annoyed with a strange sound that was disturbing my peace, I found out that the noise was a Sealscarer, a computer generated sound that kept seals away from the fish-farm further up the bay.
This is an audio recording of that noise; it was recorded onto a portable solid-state recorder that was encased in an aquapack, a fexible plastic case that is watertight till 5m depth.The knocking noise is the waves on the botton of the boat, this was unavoidable as the recorder was hand-held and the sea too rough to swim near-enough to the fish-farm. This was part of a Triangle Arts residency earlier this year, where 20 international artists worked together for two weeks on a small Scottish Island.
I've attached a PDF which is a catalogue for the sealscarer used on this particular farm. Unfortunately it has not got nearly the same amount of technical information that the user manual has, but gives some idea of how the deterrent system works.