[Heibges]

I think you can't use the deck gun above Wind 7ms.

Once you know what 7ms waves look like you can easily tell by looking through the periscope.

But until then it's either trial by error, or you have to ask your Watch Officer.

But it's not like you have been submerged for a week either. Chances are the conditions on the surface are exactly like when you submerged.

It can be dangerous just popping up close to a merchant for a gunnery raid. If they are well armed, you may find yourself with irrepairable damage to your boat in short order.