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DIRECTIONAL STABILITY ANALYSIS IN SHIP MANOEUVRING MIMET Technical Bulletin Volume 1 (2) 2010 ASSOC. PROF. IR MD SALIM KAMIL* Department of Marine Design Technology Malaysian Institute of Marine Engineering Technology, Universiti Kuala Lumpur Received: 20 May 2010; Revised: 8 July 2010 ; Accepted: 7 October 2010 Feature Article 1 ABSTRACT The directional stability analysis method presented is useful for solving directional instability problems of a vessel during the feasibility studies and design stage of a new construction or for operational ships. The governing equations and the influences of trim, rudder and skeg on the stability criteria are briefly derived. The computation of the analysis is per‐ formed using a simple program written in FORTRAN. Extracts from the computation output based on a known ship’s data are shown. One could provide recommendations for the solution of the directional instability problem of the vessel from the typical output. Apart from the stability criteria, a measure of manoeuvrability could also be investigated based on the turning radii evaluated. Keyword: Directional stability, manoeuvring INTRODUCTION Manoeuvring performance is one of the many technicalities normally checked by the ship designers during the initial stage of the design of a new construction. Corrections of directional instability can be made during or after the model tests phase. The standard tests on the particular free model are neces‐ sary to be carried out to determine the ap‐ propriate manoeuvring derivatives. The stan‐ dard tests to determine the manoeuvring derivatives carried out utilizing models in special manoeuvring tanks are oblique, ro‐ tating arm and planar motion mechanism tests. The planar motion mechanism tests which are necessary to be conducted for this *Corresponding Author: Assoc. Prof. Ir Md Salim Kamil CEng, CMarEng, PEng, FIMarEST, MIEM, was once the Dean and Head of Campus of Universiti Kuala Lumpur Malaysian Insti‐ tute of Marine Engineering Technology and a retired Commander of the Royal Malaysian Navy. He graduated with an MSc in Naval Architecture (London University ), a BSc (Hons) in Naval Architecture and Ocean Engineering (Glasgow University), a Diploma in Naval Architecture (University College London) and a Diploma in Mechanical Engineering (Universiti Teknologi Malaysia). He is currently pursuing a PhD course at St Petersburg State Marine Marine Tech‐ nical University, Russia. Email: mdsalim@mimet.unikl.edu.my Tel:+605‐6909000 purpose include the pure sway and pure yaw tests. The options available to solve the in‐ stability problem without changing the ship hull form include altering the design trim, addition of a skeg, changing the rudder size or the rudder effectiveness and any combi‐ nation of the above options. The Directional Stability Criteria The derivatives of the linearised non‐ dimensionalised equations of yaw and sway motions are derived based on the Taylor’s Theorem. Taking into consideration of small deviation or variation, the roll, surge and heave motions and the second derivatives are neglected. The linearised equations of | MARINE FRONTIER @ UniKL 3
motions of yaw and sway are simplified as fol‐ low: � � � � � � � � � � � � � � � � � � � �m � Y � � � v Y v Y m r Y �� v v v � ' (1) � �I� � N�� r � N�v� � N�r� � N� �� v r r where m’ ‐ Non‐dimensionalised mass. Y� v ' Y� v ' ‐ Non‐dimensionalised first derivative of sway force with respect to sway acceleration. Y �� v ‐ Non‐dimensionalised first derivative of sway force with respect to sway Y Y�� N �� r N �� v velocity. ‐ Non‐dimensionalised first derivative of sway force with respect to helm angle. � �� 1 2 m � L ‐ Non‐dimensionalised first derivative of yaw moment with respect to turning acceleration. ‐ Non‐dimensionalised first derivative of yaw moment with respect to sway velocity. (2) MIMET Technical Bulletin Volume 1 (2) 2010 3 � �� N Nr r N N� � � � ‐ Non‐dimensionalised first derivative of yaw moment with respect to rate of turning. ‐ Non‐dimensionalised first derivative of yaw moment with respect to helm angle. v' ‐ Non‐dimensionalised sway velocity. v � v� � ‐ Non‐dimensionalised sway accelera‐ tion. R ‐ Radius of curvature. � � r ‐ Non‐dimensionalised turning accel‐ eration. � � � I � ‐ Helm angle. ‐ Non‐dimensionalised helm angle. �� L L r� L L r�� x �� U R ‐ Non‐dimensionalised turning rate. ‐ Non‐dimensionalised second mo‐ ment of inertia of mass. Equations (1) and (2) can be written as follow: �m��Y�� ( m� � Y � � �� ) D Y � r� Y �� v v �� v v � � ��N��r��N��I��N�) D� � �� (3) v� � v � N �� r ( �� (4) r | MARINE FRONTIER @ UniKL 4
Page 2 and 3: EDITORIAL CHIEF EDITOR Prof. Dato
Page 6 and 7: The determinant from equations (3)
Page 8 and 9: Table 1 ‐ Results of Stability Cr
Page 10 and 11: DO 20 J=1,7 REFF(J)=1+((J‐1)*1.5/
Page 12 and 13: Skeg Effectiveness Skeg Effectivene
Page 14 and 15: Skeg Effectiveness Skeg Effectivene
Page 16 and 17: A WATER FUELLED ENGINE FOR FUTURE M
Page 18 and 19: Stainless steel pipes are used as e
Page 20 and 21: Current development Hydrogen Oceanj
Page 22 and 23: Car industry A small group of local
Page 24 and 25: Big oil companies. For business sur
Page 26 and 27: Websites: 1. http://www.schatzlab.o
Page 28 and 29: Table 1: Global maritime Fleet Rank
Page 30 and 31: No. of Ships No. of Ships 300 250 2
Page 32 and 33: time players is 30. The demand for
Page 34 and 35: References [1] UNCTAD, Review Marit
Page 36 and 37: Table 3 : Tug boat Registered in Ma
Page 38 and 39: NO SHIP NAME OWNER/OPERATOR GRT DWT
Page 42 and 43: MIMET Technical Bulletin Volume 1 (
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Table 8 : Tankers Registered in Mal
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NO SHIP NAME OWNER/OPERATOR GRT DWT
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Table 10: Passenger Ship Registered
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NO SHIP NAME OWNER/OPERATOR GRT DWT
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Table 11: Container Ships Registere
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age and appropriate steps must be t
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tends to oxidize rapidly, even at a
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oxide or other anti‐oxidant addit
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MIMET Technical Bulletin Volume 1 (
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METHODOLOGY Description of Apparatu
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Preparation and procedure for Mecha
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Objective of the Research The resea
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Figure 2.1: LNG Trade Volume 1998,
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Mean Median Table 3.1: Carrier Aspe
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From the result in Table 3.1, it sh
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adversely affecting ship operations
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distributed system and other equipm
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Knowledge based system is a compute
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Again Butler and Sarma [28] put for
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particle swarm optimization (PSO)[1
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MI [27] Butler, K. L, Sarma, N.D.R.
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Positive transformation from its tr
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mutually exclusive, but rather comp
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Table 2. Measurements for Integrity
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Table 5. Measurements for Excellenc
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have become a major issue without m
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used to model the pneumatic transmi
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Figure 2: Transmission Line Diamete
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PDE equations (1) and (2). Comparis
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Since chemical products have high p
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Figure 6: Enclosed life boat with s
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UNIKL MIMET AND ALAM SHIP MANAGEMEN
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