Coastguard helicopter causing a boat?

[robemcdonald]

I was on the ferry out of Yarmouth on the IoW yesterday at around 11:15am. There was a coastguard helicopter hovering over a smallish cabin cruiser that wasn't stopping. The helicopter was keeping up with the boat about 50 feet above it.
Was this a training excercise? I have had a bit of a search on the net and can't seem to see anything about it.

[robemcdonald]

Apologies if the original post wasn't very clear. I was multitasking at the time.

Basically a small cabin cruiser passed the ferry (I couldn't estimate a speed sorry)

Hovering above it was a Coast guard helicopter (a AW139 I think, but not great with helicopters)

The helicopter was keeping pace with the boat with the fuselage of the helicopter at a right angle to the hull of the boat.

The helicopter was around 50 feet off the water (maybe less)

The boat had a blue hull, but was otherwise unmarked.

There were no lines from the helicopter.

My initial thought was a training excercise but the whole thing passed quite close to the ferry, probably less than 200 metres. So I thought they wouldn't run a training excercise so close to a fairly busy shipping lane.

I will try and answer any questions, but I'm keen to know what it was.

[robemcdonald]

Also the thread title is clearly wrong. It should be chasing a boat. iPad spell checker will be sacked.