What are wind shields on a submarine?

Answer 1

A "windshield" on a submarine is a thick plexiglass shield about 4-5 feet long and 12-15 inches high that is used on the bridge (top of the sail) when the boat is underway transiting on the surface. Unless the weather is so bad that the bridge can't be manned, it is standard procedure for the bridge to be manned at all times by the Conn Officer and 2 lookouts. The shield helps divert the wind over the bridge crew, as watches are typically 6 hours and it can get pretty breezy in rough weather, when it is typically used.

The primary focus of manning the bridge on the surface with modern submarines is purely navigational - submarines are low in the water, black, and very hard to spot by commercial ships and other warships in low light conditions. Submarines on the surface transiting at night are required by maritime law to use a yellow blinking light to signal other ships a submarine is in the area. Even though Radar is used on the surface, it's not infallible, and 3 pairs of eyes with binoculars with a 360 view searching for surface contacts is considered an essential navigational safety measure.

It helps some, but if the weather is really bad it doesn't really make much difference one way or the other. Some submarines (Russian in particular) have enclosed bridges with windshields on the front and sides of the forward part of the sail. The reason the U.S. Navy and most others don't use that system is because it limits your field of view (you can't see behind you) and plexiglass gets pretty weathered when traveling underwater.

While on the surface (usually transiting to and from a port) it's common for crew to request permission to visit the bridge and get some fresh air and time to look around. The ocean is beautiful at night in calm seas, and Dolphins are usually around riding the ship's bow wave. It's one of the things I really miss about submarine life.