What are the 2 portions of propeller current?

Master the Navigation, Seamanship, and Shiphandling (NSS) – Officer of the Deck (OOD) Phase 2 Exam with engaging flashcards and multiple choice questions, complete with hints and explanations. Prepare comprehensively for your test!

Multiple Choice

What are the 2 portions of propeller current?

The water flow created by a propeller has two distinct parts that matter for steering. One is the suction current, which is the water drawn toward the propeller on the forward side. The other is the discharge current, the water expelled behind the propeller that forms a wake and washes over the rudder, helping to drive its effectiveness. This wake over the rudder is why the rudder works even when the ship is moving slowly or under power. Terms like intake/exhaust or vague forward/aft currents don’t capture these two distinct and interacting parts of the propeller’s wake.

The water flow created by a propeller has two distinct parts that matter for steering. One is the suction current, which is the water drawn toward the propeller on the forward side. The other is the discharge current, the water expelled behind the propeller that forms a wake and washes over the rudder, helping to drive its effectiveness. This wake over the rudder is why the rudder works even when the ship is moving slowly or under power. Terms like intake/exhaust or vague forward/aft currents don’t capture these two distinct and interacting parts of the propeller’s wake.

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