[Abd_von_Mumit]

From the Kriegsmarine "Submarine Commander's Handbook" that I started reading yesterday and I think everyone here should learn by heart , some excerpts about bad weather conditions:

27.) It may also be advisable to remain submerged in misty or foggy weather. In poor visibility, the approach of ships can be more easily detected underwater [from the sound of the ships' engines] by means of the hydrophone, than on the surface by the look-out.

28.) This possibility of using the hydrophone to help in detecting surf ships should, however, be restricted to those cases in which the submarine is unavoidably compelled to stay below the surface. The hydrophone must not lead to inactivity [passivity] underwater, which would be wrong; it is an auxiliary instrument and no more, and can never be a substitute for ocular perception and surface viewing. As soon as visibility allows, the, place of the submarine is on the surface. Otherwise valuable opportunities of attack are lost.

[...]

37.) Conditions are different, in particular, in areas threatened from the air, when the submarine is engaged in operations that cause it to remain stationary in misty weather, with poor visibility and low clouds. In such circumstances it is right to remain submerged during the day, because, if it has surfaced, the submarine may easily be surprised by aircraft suddenly appearing in near sight, without being able to submerge in time, and reach safety.

[...]

392.) The torpedo must always be ready for action at shortest notice. Always be prepared for unexpected opportunities of attack. A neglected opportunity will not recur.

In foggy weather and bad visibility, the tubes should be ready flooded. If necessary, they should be flooded via the mouth flaps.