Vortex Attenuator Questions

[redboat219]

How do Vortex Attenuators work?
How come I only see them on Russian and not US boats?
Other than foiling wake homing torpedoes, do they have any other use-like reducing drag?

[subicman]

Re: Vortex Attenuator Questions

How do Vortex Attenuators work?
How come I only see them on Russian and not US boats?
Other than foiling wake homing torpedoes, do they have any other use-like reducing drag?

A vortex attenuator agitates the wake from the main propeller and reducers the low pressure area created around the screw. This in turn reduces the amount of cavitation (little tiny bubbles that are created and then destroyed by sea pressure) created by the screw. Depressed cavitation is a sure sign of a submerged contact. (Dead giveaway). U.S. boats have them, but the shape and configuration are highly classified and when a boat is in dock, they are covered over with the main screw. Several of my boats that I served on had them. The shrouded screw and the pumpjets don't need them, due to their design. Other than that no other useful byproduct that I know of. Hope this helps you.