[Bear_Slayer]

Quiet diesel subs?

I drive a diesel. I hear diesel 18-wheelers on the highway. These things are noisy. How can a diesel sub be quiet?

I would think the technology would preclude that.

[ArrogantBustard]

The proper term for these boats is "diesel-electric" ... noisy enough when running the engines, of course. Extremely quiet when running on batteries.

[stuartcr]

ID of diesel subs when they are on the surface, is very difficult because they sound like any other vessel, underwater, they run on electric motors that make very little noise.

[roaddog727]

Diesel powered at the surface - battery powered under water.

VERRRRRRRRRRRRRY quiet under water where silence counts.

[FreedomPoster]

To follow up on ArrogantBustard's diesel-electric explanation, to get some idea of what a D-E boat sound like, running on batteries, go out to your garage, open your hood, and listen to your battery.

Obviously this is a bit tongue-in-cheek, but not all that much.

[pfflier]

How can a diesel sub be quiet?

The Diesel is only used on ot near the surface when charging the batteries, because it is air aspirated. The battery set(s) run electric motors. The rest of the time, when the sub us submerged, it is running on batteries. The electric motors are verrrrry quiet.

[puppypusher]

Deisel subs are quieter because they run on batteries when they are submerged so there is No powerplant noise to detect.