Theory behind Turning dynamics of ships
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- เผยแพร่เมื่อ 29 เม.ย. 2020
- SAMMON Lecturing Video describing
"Theory behind turning dynamics of ships"
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SAMMON - the IDEAL tool to identify manoeuvring capabilities of a ship - SAMMON - learning the EFFECTIVE way
Thank you so so much kind Sir, i can finally grasp the topic
Many thanks.
thanks alot,Sir!
Thank you! Could you treat in a video how can a pilot appreciate or what landmark can be used to know when to start turning the ship in a tight place so that you have enough space. I know it s not possible to pinpoint exactly, but there has to be some standard.
Excuse me, Sir. Can u design control of autonomous ship using NMPC in matlab?
Hooyer publication textbook describes these forces as “lateral resistance” forward and aft of the pivot point.
if tugboat with ASD thruster, is this test necessary? even if it can rotate fully 360°
Could you please specify what test do you mean more precisely?
How about a front rudder? Would it have similar effects to a front thruster?
Yes, it would have the same effect. But this is working only with an inflow to the rudder, i.e. when the ship is moving.
Sir ,
Is the track the movement of ship's pivot point or the COG ?
The track you see as blue line is the bridge position which was taken as Common Reference Point where the speed vector is starting...
i know this is kinda of silly question but does this apply to world of warships game as well?
The principles are the same for all ships: similar types of forces and moments, maybe different in size, balancing each other...
How sped reduces during a turn under steady engine power?
The reasons for speed reduction during a turn under steady engine power comes because:
a) an increase of resistance: mainly due to drift angle and rate of turn, but also due to the increase of rudder drag.
b) there is also an additional force against the ships motion due to the centrifugal force which has a component to the stern.
c) the direction of propeller thrust goes out of the forward motion / CTW due to the drift angle
All these components together lead to an speed loss of up to 50%, specifically for long and slender ships....
Maybe a should make another movie?...:-)
The reasons for speed reduction during a turn under steady engine power comes because:
a) an increase of resistance: mainly due to drift angle and rate of turn, but also due to the increase of rudder drag.
b) there is also an additional force against the ships motion due to the centrifugal force which has a component to the stern.
c) the direction of propeller thrust goes out of the forward motion / CTW due to the drift angle
All these components together lead to an speed loss of up to 50%, specifically for long and slender ships....
Maybe a should make another movie?...:-)
Thank you so much
The confusing thing to me is how the pivot point shifts aft yet the turning diameter decreases. You would think the pivot point moves forward through the turn, increasing the turning arm (rudder to pivot point) creating more leverage to turn the vessel tighter.
Even though the pivot point is not mentioned in this video, I think you know the concept of it since you have mentioned it here.
In the first scenario, the boat's motion is a combination of surge, sway and yaw. This means the pivot point will shift forward.
If you want to know it more specifically, check the figure 8 and figure 9 of this paper: drive.google.com/file/d/19HBN82hZKkXYJcM3dJQ-TuZ9aWHCSa9b/view?usp=sharing
One should understand that there is no leverage related to the pivot point as a sort of fixed fulcrum! because it immediately moves away when a force or moment is applied.