A frigate overtaken

There seem to be a rather active community of warmongers cruising the virtual waters. Sometimes a sub pops up at Tradewinds, but it has been a while since my last "sighting". This time I was out sailing the Dolphin Moth; Didn't take long for me to get from Tradewinds to teh Blake Sea. In fact I was just thinking: 30 knots is too fast for these waters, when I saw this vessel...

A mighty big ship

Then I realized that I was outrunning the thing. I sailed in circles around it. Portside first. I a minute or so I was in front in this unequal race. After another minute I was about to be squashed between the ship and an island, so I tried to go the other way around.

Can't that thing go any faster?

Dunno if the skipper up there got annoyed by me, but after that he set a course consistantly forcing me to beat upwind; That kinda took a factor of 1.4 off my speed; At 21knots I was left in the wake, hehe. Now, I am not an expert, but I assume this is a frigate of sorts. Also, it looks modern - or at least not like a ship from WWII-movies.

Is that a frigate?

One gun only? It must have rockets of sorts then... also there is a helipad on the aft deck, but what really interests me is that strange thing on top of the bridge... It kinda looks like a old WWII mine. What is it, and what's it doing there?

Top view

Here's another shot, where that thing is even more visible... Does anyone know what kind og ship this is, and what that thing up there is? There's an English flag flying - look closely on picture three. Perhaps it is a replica of something real?