Quote:
Originally Posted by Platapus
Given all the technology we have these days, why are not modern submarines constructed without sails?
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This is not a dumb question at all. In fact, several leading naval architects have asked the same question. They really wanted to eliminate the sail as it is a major source of hydrodynamic drag.
The main purpose of the sail was to provide a streamlined housing for the masts. These masts have to be a certain length in order to be able to penetrate the surface while at the same time keeping the boat at a deep enough depth to maintain control. This made for a fairly long mast. In order to house the mast completely when retracted, the hull of the boat would have had to be huge in cross section. This is impractical so the compromise is the sail.
The other important feature of the sail is the bridge. A partially sheltered, raised bridge is vital to safe navigation once the boat is on the surface entering or leaving port. It has to be some distance above the hull in order for the OOD and lookouts to be able to see anything.
On two separate occasions in the 1950's and 1960's the proposal to eliminate the sail was seriously put forth. However, each time the designers ran afoul of the problems that I described above. They tried one more time in 1968 during the CONFORM project, which was the first attempt at designing a follow on to the Permit and Sturgeon class SSN's. A scale model of the proposed design was built that had no sail at all. The masts and periscopes folded flush with the hull, similar to the way the snorkel mast folded on the late war German U-boats. The CONFORM design even featured a small folding bridge structure. This project would have produced a radically new and different submarine if it had been built. However, Admiral Rickover was adamantly opposed to these radical changes and championed the more "conservative" SSN-688 design. Rickover's forceful protestations eventually won out. CONFORM died and his design eventually became the Los Angeles class.
Realistically, we are only just now coming into a technology level that will permit the removal of the sail structure. CONFORM would have stretched the state of the art to its limits, and ultimately may not have been practical. Our newest submarines of the Virginia (SSN-774) class have non penetrating masts (i.e. they don't retract into or penetrate the pressure hull). This would allow a serious reduction in sail size. See this link for an artists impression of a proposed sail design for later Virginia class boats:
http://www.navsource.org/archives/08/0877413.jpg