Wheelhouse window

[hayhugh]

I left the Lakes back in the early 70s. At that time the front window was always open, maybe not all the way, but enough to see out and near if another vessel blew her whistle. Before someone entered the Pilot House they had to knock so the Mate could close the window and then the window was again opened. I have been on the wheel when the Captain would Tell the Mate that he would stand by while the Mate went below to get his rain gear because it looked like it would be a wet night in the river. The front window would be open day or night, rain or shine, in the rivers or out on the lake.

[Bob Graham]

The device is called a Clearview.

[CG Bob]

It's a rotating clear view screen, a type of windshield wiper. There is a motor on the inside of the window that spins the round window - throwing off the rain or sea spray.

[C Pike]

On every vessel I have seen either salty or laker, even smaller vessels like USCG, or CGC, there is a circle window attached to the main window usually in the centre or off to one side.
What is this additional window, and how is it used?
This may have been answered previously.
Charles Pike