What do they mean by "down bubble" when there in a submarine?

Question

On TV when they say the submarine is going down they say "down bubble" How much is that what is down bubble?

Answer 1

If you have ever used a level, the bubble on the indicator will show if an object needs to be raised or lowered on one end or another of the object being leveled.So on a submarine the command will either be UP bubble or DOWN bubble depending on which way the ship needs to go.

Answer 2

Several clarifications required.

You are presumably watching a show with a diesel submarine (i.e., WW2 movie).
Diesel subs had a slightly upward angle when riding on/near the surface.
The bubble merely indicates the front-to-back angle of the sub, so a down bubble means the submarine is pointed downward. It does not mean the sub is actually going down!

So, saying the sub has a down bubble means that the sub is ready to start diving and/or already is. Basically, "we've started going down."

Answer 3

Think of the slightly curved glass tube in a carpenter's level which contains liquid and a small bubble. When the left end is tilted up the bubble goes to the left and vice versa. The same would apply to the bubble in a sub. Its actually an inclinometer which indicates which way the bow is pointing. Down bubble means the bow is down, they're diving.

Answer 4

The inclinometer is a horizontal-mount slightly curved glass tube that is almost completlty filled with fluid. If sub is level the bubble is in the center; if sub is angled the bubble moves along the length of the tube, which is marked in degrees. Imagine a marked carpenter's level.

Answer 5

Bubble Sub

Answer 6

Really not sure about this one

Answer 7

It depends..