Hoving (?) into view was an oil/gas rig. Presumably one of the submersible ones which arent anchored on the sea bed but sort of float, and can be towed in by tugs to wherever to be repaired or whatever.
Since the land that is going to be drilled cannot provide a base for offshore drilling as it does for onshore drilling, an artificial platform must be created. This artificial platform can take many forms, depending on the characteristics of the well to be drilled, including how far underwater the drilling target is. One of the most important pieces of equipment for offshore drilling is the subsea drilling template. Essentially, this piece of equipment connects the underwater well site to the drilling platform on the surface of the water. This device, resembling a cookie cutter, consists of an open steel box with multiple holes in it, dependent on the number of wells to be drilled. This drilling template is placed over the well site, and usually lowered into the exact position required using satellite and GPS technology. A relatively shallow hole is then dug, in which the drilling template is cemented into place. The drilling template, secured to the sea floor and attached to the drilling platform above with cables, allows for accurate drilling to take place, but allows for the movement of the platform, which will inevitably be affected by shifting wind and water currents. Courtesy of NaturalGas.org.Okay, got all that? Normally we dont see the platforms as they are miles out, so this one was being towed, probably into Peterhead, where we have seen them towering above the harbour and being refurbished.