MAY 2021 SHIP VIBRATION

1 GUIDANCE NOTES ONSHIP VIBRATIONMAY 2021 American Bureau of ShippingIncorporated by Act of Legislature ofthe State of New York 1862 2021 American Bureau of Shipping. All rights City Plaza DriveSpring, TX 77389 USAF oreword (1 May 2021)The American Bureau of Shipping recognizes the overall ship VIBRATION as an important measure to ensurethe habitability, safety and functionality of the vessels. The ABS Guidance Notes on ship VIBRATION havebeen developed to provide users with specific guidance on the design , analysis, measurement proceduresand criteria in order to achieve the goal of limiting the ship VIBRATION to an acceptable level.

2 In the textherein, this document is referred to as these Guidance Notes .The design and construction of the hull, superstructure, and deckhouse of a steel vessel are to be based onall applicable requirements of the Marine Vessel Rules. Specifically, for the Container Carriers over 130meters in length, the ABS Marine Vessel Rules require the consideration of vibratory responses of hullstructures, as applicable (5C-5-3 ). For the LNG Carriers, the ABS Marine Vessel Rules require specialattention to the possible collapse of membrane due to hull VIBRATION (5C-8-4 ). For ship -type floatingproduction units with spread mooring, the ABS Rules for Building and Classing Facilities on OffshoreInstallations require the flare tower/boom and hull natural frequencies to be separated to avoid resonanceor near resonance (3-3 ).

3 In conjunction with the propulsion shaft alignment, the Marine Vessel Rulesrequire the consideration of propulsion shaft vibrations (4-3-2/7). For the cargo and passenger vessels,ABS provides optional classification notations for crew habitability and passenger comfort (ABS Guide forPassenger Comfort on Ships and Guide for Crew Habitability on Ships). Also ABS provides ConditionMonitoring Program for machinery VIBRATION (7-A-14 of the ABS Rules for Survey AfterConstruction (Part 7)).These Guidance Notes provide practical guidelines on the concept design to assist ship designers to avoidexcessive shipboard VIBRATION at an early design stage.

4 These Guidance Notes also assist with the finiteelement analysis (FEA) based VIBRATION analysis procedure to calculate the VIBRATION response and evaluatethe design at detail design stage. The analysis procedure represents the current analysis practice in Guidance Notes also offer guidelines on the VIBRATION measurement procedure at sea trials and theacceptance criteria on VIBRATION limits based on the international standards and the practice in 2018 edition provides guidance on quick local VIBRATION analysis methods for 2021 edition introduces a new coefficient of the Kumai formula for calculating the hull girder 2-nodevertical VIBRATION mode natural frequency of ship -type floating production Guidance Notes become effective on the first day of the month of are advised to check periodically on the ABS

5 Website to verify that this version ofthese Guidance Notes is the most current. Comments or suggestions can be sent electronically of UseThe information presented herein is intended solely to assist the reader in the methodologies and/ortechniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of aqualified professional. It is the responsibility of the reader to perform their own assessment and obtainprofessional advice. Information contained herein is considered to be pertinent at the time of publication,but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or moreupdated information and the reader assumes full responsibility for compliance.

6 This publication may not becopied or redistributed in part or in whole without prior written consent from GUIDANCE NOTES ON ship VIBRATION 2021iiGUIDANCE NOTES ONSHIP 1 Overall Procedure for ship VIBRATION design Main Diesel .. Pressure 24 TABLE 1 External Forces and 2 Guide Force 3 Nominal Wake Distribution for a Typical MerchantShip(DTMB Model 4370, CB= )..16 FIGURE 4 Alternative Shafting Arrangements: Open Strut Stern(upper); Conventional Skeg Stern (lower)..17 FIGURE 5 Open Strut Stern 19 FIGURE 6 Conventional Skeg-Stern 19 FIGURE 7 Maximum Skew 8 Burrill Cavitation Inception GUIDANCE NOTES ON ship VIBRATION 2021iiiSECTION4 Structural Girder Vertical VIBRATION .

7 265 Main Machinery/Shafting System Longitudinal VibrationExcited by the Propeller ..307 Superstructure Fore-and-Aft VIBRATION Excited ..34 TABLE 1 Comparison of 2-node Vertical VIBRATION 27 TABLE 2 Flexible Base Correction 1 Natural Frequencies of Vertical Hull 23-mass Longitudinal Model of Main Propulsion 31 FIGURE 3 Example of Natural Frequencies vs. Foundation 33 FIGURE 4 Deckhouse 5 Fixed-base Superstructure Natural 35 FIGURE 6 Deckhouse 37 SECTION5 VIBRATION and Outline of ship VIBRATION Element , Propeller Shaft and Weight , Water Ballast in Tanks and Fuel Oil in Structural Component Models (1 February 2018).

8 Structural Panel Models (1 February 2018).. 445 Loading of Loading Conditions and ship Mass (1 February 2018).. Shaft Surface Forces Induced by Propeller Calculation of Bearing and Surface 54 ABS GUIDANCE NOTES ON ship VIBRATION 55 TABLE 1 Propeller Bearing Forces and Moments for 20 RealShip Case 49 FIGURE 1 Procedure to Perform ship VIBRATION 2 Global FE Model 41 FIGURE 3 Engine Model 4 Turbine Engine and Propeller Shaft Modeling 43 FIGURE 5 Propeller Shaft .. 43 FIGURE 6 First Two Vertical Mode 7 First Two Horizontal Mode 8 Scale Effect due to Propeller Inflow 573 Instrumentation.

9 And Engine Engine and Thrust Shaft Shaft Deck Machinery and Near Processing of GUIDANCE NOTES ON ship VIBRATION 2021v11 Measurement and Reporting of 65 TABLE 1 Typical Frequencies 2 Examples of Alternate VIBRATION Limits for Crew and Criteria for Crew Habitability and 6954 (1984) Criteria for Crew and PassengerRelating to Mechanical 6954 (2000) Criteria for Crew and PassengerRelating to Mechanical 695 VIBRATION Limits for Local Limits for Machinery .. Propulsion and 1 Maximum Weighted RMS Acceleration Levels for 2 Maximum Weighted RMS Acceleration Levels forPassenger Comfort.

10 68 TABLE 3 Overall Frequency-Weighted RMS Values (ISO 6954:2000)..70 TABLE 4 VIBRATION Limits for Main Propulsion Machinery ..72 FIGURE 1 ISO 6954 (1984)..69 FIGURE 2 VIBRATION Limits for Local 763 General Modifications ..777 Structural Modifications .. 799 Case Study .. of Model 80 ABS GUIDANCE NOTES ON ship VIBRATION Rectification 1 Wake Improvement with Special Lines-adapting SternDevices Conventional Stern Cargo 2 Mass-elastic Model of Deckhouse and Support 3 Equivalent One-mass Excitation and Flare Slamming and Impact design GUIDANCE NOTES ON ship VIBRATION 2021viiS E C T I O N1 General1 IntroductionWith the increase of ship size and speed, shipboard VIBRATION becomes a great concern in the design andconstruction of the vessels.