Trim Tank

The trim tank is located at the center starboard side of the control room. It has three gauges and two handwheels. The left most gauge shows the current amount of water in the trim tank. The center gauge is the coarse depth gauge, and shows water above keel, with each minor line representing 2m, intermediate lines 10m and major lines 20m. To the right is the fine depth gauge. This gauge makes one full revolution for every 10m, with each line representing 0.1m, intermediate lines 0.5m and major lines 1m. One can think of the fine gauge as the minute hand on a clock, while the coarse gauge is the hour hand. And thus these two gauges makes up the most accurate depth gauge on the boat.

The left hand wheel controls the flooding of the trim tank, and the right blows the trim tank. The wheels are moved by moving the mouse over the wheel, left clicking and moving the mouse left or right. It is important to make sure you have properly closed the valves when you are done, as they will stay in what ever state you leave them in.

The main purpose of the trim tank is to fine adjust the buoyancy of the boat so that it can maintain a close to neutral buoyancy. At the start of every session the boat will start with a randomized amount of water in the trim tank, as well as a randomized weight. In order to achieve neutral buoyancy the boat must be submerged to a depth of at least 12m and the dive planes set to a neutral angle. If the boat is ascending, the trim tank must be flooded more, if it is descending it must be blown. With a delicate touch on the controls and a bit of patience, one can achieve perfectly neutral buoyancy by observing the fine depth gauge, and make sure it remains stationary with both valves closed.

When firing torpedoes, the boat gets lighter, and more water has to be added to the trim tank for each torpedo in order to maintain neutral buoyancy.