[Phaedrus]

If the definition of stall is a loss of control of the vessel because of a disruption in the flow of water over it's control surfaces, I would say submarines can indeed stall.

Submarines do rely on forward momentum to some degree to maintain depth and heading.

A good way of looking at it is to say that the ship uses the ballast and trim tanks to determine where it is at the present moment, while the planes and rudder control where the boat will be in the soon-to-be-present future.

The flooding and blowing of the ballast tanks controls depth, but the majority of underway submerged flooding and blowing has to do with maintaining the boat's trim.
Once the boat achieves a neutral buoyancy, trim needs to be adjusted based on water density and other factors to allow the boat to be controllable, and remain on a (relatively) level plane.
The fact that there is air left in a partially flooded ballast tank means that the submarine is destablized by the 'free surface' effect of water (a good example of this is the difficulty in trying to carry water in a wide flat pan)... much of trim adjustment is to find the stabilizing balance.


The dive planes and rudder determine the ship's future position by moving to provide resistance as water hits (or rather, flows over) the surface of the planes.

The minimum amount of momentum needed to be able to maneuver the boat via the helm is known as steerageway.

While it is techincally the true that the dive planes do not make large adjustments to the depth of the boat, they do make an ascent or descent controllable, ensuring that the boat glides smoothly to the desired depth - rather than plummetting to unsafe depths or rocketing out of the water like a cork rising from under water.

Though the formal definition of a stall is obviously aeronautical in nature (disruption in the flow of air over an airfoil, resulting in a loss of lift; thereby inducing a loss of control and altitude until sufficient lift is once again established), a similar state could be said to be induced in a boat during a dive (a negative buoyancy situation) - where no combination of high degree of up-angle on the dive planes, and forward momentum would be sufficient to propel the boat upward because of lack of buoyancy.

... or perhaps during an unwanted ascent, where the boat was trimmed with a slightly positive buoyancy, but a combination of forward motion and bow planes down led to a minute and continuous dive rather than an ascent. If the boat reduced revolutions to a speed below what was necessary to overcome the very slight buoyancy and dive, it would rise without control unless the boat adjusted trim, or increased speed.


I think that a lack of steerageway (though in this case, referring to both the helm and the planes, rather than just the helm in the typical nautical sense of 'steerageway'), would be the submersible equivalent of a stall.