This circular is due to a problem created by service
vessels waiting to dock
with the north sea oil
rigs. These vessels would sometimes have very long waits before they could approach an oil
rig. They would shut down the engine
, indicate NUC, and go below. The problem was that Icelandic fishing
vessels also plied these waters. With their nets deployed the fishing
vessels are restricted in their ability to maneuvre. The service
vessels were drifting into the path of the fishing vessels creating an unnecessary hazard. This is clearly not an exceptional circumstance but rather a routine practice.
OTOH, the rules do provide for a vessel to indicate that it is NUC and drifting as well as being NUC and underway. The problem is that "exceptional circumstance" is not defined in the rules. The oil rig service vessel skippers figured that going around circles for hours was an exceptional circumstance. Maybe, if their hadn't been any fishing vessels around they would still be drifting and watch TV.
IMHO, it is always best to provide the most accurate infomation possible about your vessel to other vessels that may cross your path. That way, on the rare chance that you should come across another sailing vessel while you are below, they will know what to expect from you.