Video

Theory behind Turning dynamics of ships

published on 6 May 2020 - 2304 -

Show comment section |

Found on YouTube. Created by

"ISSIMS GmbH - Marine Prediction Technology"

SAMMON Lecturing Video describing

"Theory behind turning dynamics of ships"

-------------------------------------------------------------
SAMMON - the IDEAL tool to identify manoeuvring capabilities of a ship - SAMMON - learning the EFFECTIVE way

Comment by Gunter Schütze via LinkedIn:
"Prof. Benedict a very interesting video by HS Wismar / Maritime Simulation Center Warnemünde ( MSCW) & Innovative Ship Simulation and Maritime Systems GmbH (ISSIMS). Excellent and understandable the dynamic effects of the forces and moments in turning circle explained. A really good illustration for students, nautical officer and Captains to lead them to the dynamic basics and to refresh the knowldege. I can only recommend this video. Thanks for sharing."

Germany, Wismar

ISSIMS GmbH
Innovative Ship Simulation And Maritime Systems

Education

Join the conversation...

Knud Benedict Germany

on 21 December 2020, 11:49 UTC

Thanks to Gunter for the recommendations and Michael for bringing in ideas and questions. To answer your questions, I like to explain the following:
1) The transverse force Y(ß) can be explained by two models:
a. Either it can be seen from its nature as a Lift force, i.e. the same force who lifts an airplane wing up in the air, works now horizontally on the ship hull due to the drift angle ß. It is generated by the uneven force distribution caused by an additional circular flow around the body (wing, or here the ship’s hull). This lift force has it maximum close to the wing nose – this means for the ship it is working more to the bow, so it turns the ship: I made an additional movie on that effect at out ISSIMS website on YouTube (“Effect of Drift Force and unstable moment”, https://youtu.be/agQPMQNwhxU.)

b. A second way is to look at the effect of the transverse speed along the ship length (This as named as “Slender body theory”). You are right that the transverse speed distribution is constant. However, the force due this inflow is not constant: because of the friction in the flow there is a boundary layer around the ship which is getting thicker to the stern and therefore the transverse forces are smaller at the stern than on the bow – this model also explains why the bow turns to increase the drift angle, which is called as unstable moment.
2) The "additional force at the stern" Y(r) is not just the aft component of the above evenly distributed drift force. The rotation /Rate of Turn creates a linear transverse speed distribution with maximum at bow / stern and minimum / zero at the ships center. This has an effect which can be explained by the wing/lift model under a) as curved centerline of the wind profile
3) You are right: A centripetal force is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path - so in case of the ship motion on a circle these are the forces due to drift Y(ß) and turning Y(r). These forces are balanced by the centrifugal forces (which is Ycentrifugal in the movie). The ship is able to move in a steady state motion - This is also an equilibrium condition at constant speed and also constant rate of turn.
I do hope my explanations are of some help for professional as you are. And I should underline that these are attempts of us as humans to understand the nature – that’s why I mentioned two models (there are even more…). And they are not “Laws” - even the equations of Newton and Einstein are not Laws, but they represent our current views and approaches to describe the nature with our brain in order to think and plan ahead (– and have to be checked and approved continoulsy in daily life). In this way I made some comments in my movie about “digital twins” as key maritime innovations (https://youtu.be/jYRq6xRrVUw) you can have I look if you like.

[show more]

Mr Michael Nicholson Shipmove Ltd., United Kingdom

on 7 May 2020, 09:43 UTC

I either; don't fully understand, or disagree. 1) Why must the working force (transverse force) Y(B) be acting close to the bow. The rudder is providing a moment, I don't see why/how the ship also provides a turning moment. The drift angle of the ship to its bodily movement is uniform. Surely the forces would be distributed evenly?
2) Is the "additional force at the stern" Y(r) not just the the aft component of the above evenly distributed drift force.
3) The use of the term Equilibrium, is this correct? For an object to describe an arc or a circle requires an acceleration towards the centre, caused by centripetal force. This is not in equilibrium. Equilibrium would be a straight line at uniform speed.

Video Pivot Point Demo - HS Wismar

published on 10 July 2020

SAMMON Lecturing Video describing
"Pivot Point Demonstration"
-------------------------------------------------------------
SAMMON - the IDEAL tool to identify manoeuvring capabilities of a ship - SAMMON - learning the EFFECTIVE way

Video SAMMON Intro Ships Manoeuvring Predictions

published on 11 July 2020

SAMMON Introduction into Ships Manoeuvring Prediction
- newly made Video to display the principles of SAMMON

Video Knud Benedict Presentation on “Digital Twins” at IMLA SMU Seminar

published on 28 October 2020

This is the recording of the presentation with the title:
“Digital Twins" as Key Maritime Technology Innovations for MET - and for Operation of Intelligent Ships
It was held at the MET Training Course by Shanghai Maritime University on Oct 27 2020 on the occasion of IMLA 40th anniversary

Video AMPI Marine Pilot Profiles Webinar - November 2021

published on 16 November 2021

Thanks to Jacqui Kenyon, Chevi King and Kate Delisky for joining Jeanine Drummond on this webinar to discuss their careers and pathways into marine pilotage. The audience was a great mix of experienced marine pilots and newer maritime industry participants, as well as school aged children, with people joining us from Australia and overseas. It was an opportunity to create greater awareness of the maritime industry, and the important role marine pilotage plays in protecting our port...

Opinion 1000 stanchions around… Which ones are correct and which ones are killers?

by Arie Palmers - published on 6 December 2022

Stanchions therefore are an often-overlooked part of a pilot transfer arrangement and therefore I
want to give them more attention in this article. They proved to be the cause of a whole series of accidents, some of which were even fatal.

Article Education And Training Of Pilots In The Netherlands

by Eline van der Vlist-Lammers (Coordinator education and training for STODEL) and Ed Verbeek (Master Mariner) - published on 30 September 2022

Article originally published in SWZ|Maritime September 2022

Through the years, the Dutch Pilots have developed a system of selection, initial education and continual professional training. What is the current state of affairs?

Article IMPA Information on Pilot Transfer Operations (May 2024)

published on 13 May 2024

This document aims to provide information to pilot organisations and/or competent pilotage authorities on the conduct of pilot transfer operations.

Article Pilots and VTS operators working together to improve maritime safety

published on 2 February 2022

The Norwegian Coastal Administration has signed an agreement with Aboa Mare to provide a new
course for pilots and VTS operators. By practising together in a simulator, maritime safety along the
Norwegian coast will be reinforced.

Video Pilot boarding via Helicopter

published on 14 April 2021

Video Cosco Shipping Galaxy breaks away from Felixstowe as showers passes through. 11th October 2020

published on 13 October 2020

The Cosco Shipping Galaxy alongside Felixstowe Berth 9 cargo operations come to an end with the cranes beginning to boom up. Mooring gang in attendance and the tugs begin to go to station. The pilot requests for both to make fast on the centre lead fore and aft. Svitzer Kent makes fast centre lead aft while the Svitzer Sky makes fast centre lead forward. The Sky comes under the bow to pick up the heaving line but the crew slackens the head lines before the last crane had boomed up. Sky...