I live on a lake and swim quite often. When you go underwater and a boat goes by a 1/4 mile away, you can distinctly hear the prop and engine whirring. Also, the boat sounds much closer and louder than it does above water because sound travels better in water than in air. This is because it is more dense than air.
Yes the U-Boat can stay under water.
Buoyancy affects a boat by keeping it "on" the water, not "under" the water.
Sound waves propagating through the water do.
they jump into the water and save the swimmer usually by swimming or by boat depends how close or how far the attack is.
No because the firt tendancy of the boat going in reverse is to dig the back end of the boat under water, witch causes the boat to go under water and sink.
Stay with your boat, and climb out of the water if possible. A boat is easier for rescuers to see, than a single person in the water. Don't attempt to swim from the boat, unless you are a good swimmer, you are wearing a life-jacket, and the land is not too far away.
A fishing boat using sonar to locate fish is employing reflection. The technique that uses sound propagation to detect objects under the water.
Always turn engine off when a swimmer is re-boarding
Always turn off engine when A swimmer is reboarding
Always turn off engine when A swimmer is reboarding
a under water boat hmm... titanic (kidding) submarine
U = Unter (in German) = under so is a boat that goes under (the water) namely a submarine