Dive planes

[_Seth_]

Why does modern subs have their dive planes at the conning tower, when the WWII-era subs didnt?

[Shaffer4]

My first guess would be the positioning of the Tower closer to the bow of the ship on the newer subs, that and Ice-breaking operations?

My guess would be that WWII-era submarines were basically surface boats that had the ability to submerge. They primarily spent their time on the surface, and had dive planes at the bow to help the boat dive rapidly. Whereas modern submarines are designed primarily as submerged vessels, and placing them at the conning tower probably reduced both drag and noise.

One thing to keep in mind that many people are mistaken about. The ballast and negative tanks' primary function weren't, exactly, to submerge and surface the boat, although they did play a part in that and would, on their own, do so. The dive planes were what inclined the boat and greatly assisted submerging and surfacing it when the boat was under power. The ballast and negative tanks effected the boat's bouyancy. Granted, they work hand in hand: dive planes alone won't drive a boat under with fully empty tanks nor will they keep constantly afloat one with fully flooded tanks. Likewise, with the planes set neutral, flooding the mains and negative will submerge the boat and blowing them dry will surface it (albeit at a very slow rate of descent/ascent). But the design of the system is for the tanks to affect bouyancy (and depth), and the planes to effect the inclination of the boat, which in turn (when under power) effects how quickly it rises or sinks.

So having dive planes at the bow, already underwater, means that WWII-era boats can begin a dive without the tanks being, as yet, flooded. While modern boats, spending the majority of their time submerged, can place the planes for best effectivity without needing to worry about their dive times.

[_Seth_]

Thanx guys, made it easier to understand now!