This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 7 STANDARD MANEUVERING TESTS This section describes some of the typical maneuvering tests which are performed on full-scale vessels, to assess stability and performance. 7.1 Dieudonn´ e Spiral 1. Achieve steady speed and direction for one minute. No changes in speed setting are made after this point. 2. Turn rudder quickly by 15 → , and keep it there until steady yaw rate is maintained for one minute. 3. Reduce rudder angle by 5 → , and keep it there until steady yaw rate is maintained for one minute. 4. Repeat in decrements of-5 → , to-15 → . 5. Proceed back up to 15 → . The Dieudonn´ e maneuver has the vessel path following a growing spiral, and then a con- tracting spiral in the opposite direction. The test reveals if the vessel has a memory effect, manifested as a hysteresis in yaw rate r . For example, suppose that the first 15 → rudder deﬂection causes the vessel to turn right, but that the yaw rate at zero rudder, on the way negative, is still to the right. The vessel has gotten “stuck” here, and will require a negative rudder action to pull out of the turn. But if the corrective action causes the vessel to turn left at all, the same memory effect may occur. It is easy to see that the rudder in this case has to be used excessively...
View Full Document
This note was uploaded on 02/27/2012 for the course MECHANICAL 2.154 taught by Professor Michaeltriantafyllou during the Fall '04 term at MIT.
- Fall '04