Pardon me, the "Similar Threads" sidebar brought me here...
A common theme for future submarines has been going totally sail less. That or extendable types. Would it make the hull stronger in that area if the hull form was to have greater circumferende to allo the sub to ride higher and achieve the same effect as a sail/conning tower?
Before the Virginia class and the fiber-optic "photonics mast" periscope, it just wasn't possible to go without a sail. The traditional periscope is a single tube that is however long. Hull diameter, maybe plus some. It doesn't telescope, it's just 40ft long or whatever. It gets raised by hydraulic power to bring the eyepiece end up to the control room, and then stick up however far that is above the top of the sail.
So there are 5 holes in the hull under the sail. 2 for the periscopes, one for the bridge access hatch, Snorkel Mast (air in), and diesel exhaust (air out). The periscope holes are tiny in comparison, maybe 10"/25cm across.
You're not getting rid of the other 3 holes. You have to be able to get up to the top of the sail, that's where the bridge is on the surface. You have to have the snorkel mast to take air into the boat. And you have to have the diesel exhaust to get air out.
On something like a Virginia-class, the Snorkel Mast is 18" in diameter, exhaust is less than that. On an Ohio-class, the snorkel mast is a 36" diameter hole in the hull...