FirstClassSkeptic wrote:[ How do crewmen on a sub know if they are submerged or surfaced?
They can see that they are on the surface via the periscope. There are depth gages that show the depth of the keel. When on the surface and not rigged to submerge the bridge hatch is open and there is a lookout on top of the sail. Prior to surfacing, the ship rigs the ship for surfacing. The lower pressure blower is also used to blow the ballast tanks dry after the sub drives to the surface and when it is operating it can be heard throughout the ship. There is also much more rolling around on the surface. With a portion of the round hull out of the water, the stern planes are not able to maintain much axial stability.
I also had another way to determining that we were on the surface even if I ignored everything else. Each sub has what is called a beta counter to count radioactive coolant samples. The background radiation level is determined each day and when something happens that changes the background radiation level in the lab. Due to the thick shield forward of the reactor compartment, the operations compartment of the sub received more radiation from the sun than from the reactor plant. So when on the surface, I could tell from the radiation level as determined by this sensitive instrument.