U 1: diving and hovering (3D)
About this app
Germany's first submarine of 1906: flood the ballast tanks, hover with the regulating tank, feel pressure and depth.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
How a submarine dives and surfaces
A submarine dives by flooding its ballast tanks: water replaces the air inside, the boat gets heavier until its weight exceeds its buoyancy. Buoyancy is the weight of the displaced water (Archimedes' principle). Once the boat is fully submerged it hardly changes with depth, because water is almost incompressible. Hovering therefore means weight and buoyancy are equal, fine-tuned with a compensating tank. The crew controls depth with speed and diving planes and the attitude with trim tanks. To surface, compressed air pushes the water out of the ballast tanks.
What the app shows
The app reconstructs U 1, the first submarine of the German navy (Germaniawerft Kiel, launched 1906, 42.39 m long, 238 t surfaced and 283 t submerged). As in the Deutsches Museum in Munich, the side is opened: outer hull, pressure hull, three ballast tanks with a visible water level, trim and compensating tanks, batteries, kerosene engines and electric motors, compressed-air bottles and diving planes. Arrows show weight and buoyancy, a depth scale the water pressure in bar. The permitted diving depth of 30 m and the merely calculated crush depth are marked. The app states its assumptions openly.
What you can try
You go through the sequence step by step: surfaced, flood, hover, depth control, blow. With the compensating-tank slider you feel how fine the balance is: just 0.3 t too much water makes the boat keep sinking slowly. You set speed, diving planes and trim, let a planesman hold a set depth and watch the pressure grow with every metre. An AI tutor can demonstrate the app and answer your questions directly in the scene.
Frequently asked questions
- Why does a submarine sink when it floods its ballast tanks?
- The incoming water makes the boat heavier while its volume stays the same. As soon as the weight is greater than the buoyancy, the weight of the displaced water, it sinks. On U 1 about 45 t of water were added when flooding.
- Does a submarine's buoyancy increase at greater depth?
- No. Fully submerged, the boat displaces practically the same amount of water at every depth, so its buoyancy stays the same. That is why there is no depth at which a submarine stops by itself; hovering has to be maintained with the compensating tank or with speed and diving planes.
- How high is the water pressure at 30 m depth?
- With p = ρ · g · h and seawater (1025 kg/m³) it is about 3 bar on top of atmospheric pressure, roughly 30 tonnes of force on every square metre. 30 m was the permitted diving depth of U 1.
- What can I adjust in the U 1 app?
- The fill of the ballast tanks, the water in the compensating tank, speed, diving planes, trim and a set depth. You can also toggle labels, force arrows, water pressure and the outer hull and read depth, pressure and forces in the Values panel.
Subject: Physics experiments (Deutsches Museum)
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