Terms related to ship handling
Athwartship component of propeller thrust. |
When engine works ahead of a right screw vessel,
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When engine works astern of a right screw vessel,
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When engines works ahead, a spiral flow of water is thrown towards rudder. | |
It is opposite to transverse thrust. |
When a vessel moves ahead, a cavity is created at stern. | |
Water from sides flow and swirl to fill the cavity, which is called wake current. | |
Steering will be adversely affected as the rudder works in partial vacuum. | |
Propeller works in disturbed water, speed will be lost, vibration will set up. | |
Wake current increases with speed. | |
In a finely sterned vessel, wake current is less. | |
When engines work astern, wake current is less and propeller is not affected. |
When a vessel moves ahead, belt of water is drawn along the hull, which is called frictional wake. | |
This frictional wake creates a resistance to upper blades of propeller. | |
As a result, transverse thrust reduces. |
Updated: 22-Sep-2007