GB/T 43501-2023 Ships and marine technology - Guidelines for measurement, evaluation and reporting of vibration with regard to habitability on specific ships
1 Scope
This document gives guidelines for the measurement, evaluation and reporting of vibration with regard to habitability for all persons on board ships satisfying one or both of the following conditions:
a) 2-stroke cycle, long-stroke, low-speed diesel engine directly coupled to the fixed-pitch propulsion propeller is installed.
b) length of deck house is limited as compared with its height (i.e. deck house of around 1 and above). An example of length of deck house (L) and its height (H) for slenderness ratio is shown in Annex A.
Overall frequency-weighted r. m. s. vibration values in the frequency range 1 Hz to 80 Hz are given as guidance values for different spaces on ships.
This document is applicable to specific ships with intended voyages of 24 h or more.
This document specifies requirements for the instrumentation and the procedure of measurement in normally occupied spaces. It also contains analysis specifications and guidelines for the evaluation of ship vibration with respect to habitability.
This document is not applicable to machinery spaces, other than engine control rooms, where persons do not stay for prolonged periods of time.
ISO 20283-5 is generally applicable to all ships. Requirements for measurement, evaluation and reporting of vibration with regard to habitability for all persons on board passenger and merchant ships, including specific ships to which this document may also be applicable can be found in ISO 20283-5.This document is only supplementary to ISO 20283-5.The shipbuilder can select either this document or ISO 20283-5 to apply to any specific ship upon due consideration to individual design conditions of the ship and, if any, experience in building sister or similar ships, and that particular selection is intended to be agreed on by the shipowner.
The evaluation of low-frequency ship motion which can result in motion sickness is covered by ISO 2631-1. For the evaluation of the global structural vibration of a ship, however, see ISO 2631-2.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2041 Mechanical vibration, shock and condition monitoring - Vocabulary
Note: GB/T 2298-2010 Mechanical vibration, shock and condition monitoring – Vocabulary (ISO 2041 : 2009, IDT)
ISO 2631-1 Mechanical vibration and shock- Evaluation of human exposure to whole- body vibration- Part 1: General requirements
Note: GB/T 13441.1-2007 Mechanical vibration and shock - Evaluation of human exposure to whole-body vibration - Part 1:General requirements (ISO 2631-1:1997,IDT)
ISO 2631-2 Mechanical vibration and shock - Evaluation of human exposure to whole body vibration- Part 2: Vibration in buildings (1 Hz to 80 Hz)
Note: GB/T 13441.2-2008 Mechanical vibration and shock - Evaluation of human exposure to whole-body vibration - Part 2: Vibration in buildings (1Hz to 80Hz) (ISO 2631-2:2003, IDT)
ISO 8041 Human response to vibration- - Measuring instrumentation
Note: GB/T 23716-2009 Human response to vibration - Measuring instrumentation (ISO 8041 : 2005, IDT)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2041 and the following apply.
3.1
accommodation space
space intended for recreational and administration use, namely cabins including day and sleeping rooms, hospitals, mess rooms, recreation rooms
Note: Examples of recreation rooms are lounges, smoke rooms, cinemas, gymnasiums, libraries, hobby rooms and game rooms.
3.2
office
space or room for carrying out a ship's business
Example: Deck office, ship office, meeting rooms.
3.3
work space
space allocated predominantly for manual work, namely workshops, laundries, galleys and laboratories, but not machinery space (3.4)
3.4
machinery space
space which contains steam or internal-combustion machinery, pumps, air compressors, boilers, oil fuel units, major electrical machinery, oil filling stations, thrusters, refrigerating, stabilizing, steering gear, ventilation and air conditioning machinery, etc, and trunks to such spaces
3.5
duty station
work space (3.3) where crew members typically stay over prolonged periods of time (typically for a watch of 4 h) to monitor navigation or machinery
Note: Main duty stations are the engine control room and the wheel house excluding bridge wing areas.
3.6
open-deck recreation space
designated space on the open deck to be used for the purpose of recreation
3.7
free route
condition achieved when the ship is proceeding at a constant speed and course with helm adjustment of +2° or less
4 Instrumentation
4.1 General requirements
Measurements in accordance with this document may be carried out using different types of measuring and recording equipment, e.g. instruments of digital, spectral or time-based type. The measuring instrumentation shall meet the relevant requirements of ISO 8041.
It is acceptable to use instruments manufactured in accordance with ISO 8041 that have frequency indications above 80 Hz provided that the filter characteristics comply with ISO 2631-2 (for frequency weighting, Wm, see Annex B]. The compliance of the instruments with the specifications of ISO 8041 requires a calibration of at least every two years. The date of the last calibration shall be reported.
If further data analysis is required following the measurement analysis as described in this document, the measurement data should be recorded with an electronic system which produces permanent records.
4.2 Functional test
Each channel of the instruments shall be checked on board the ship prior to and after each measurement series to ensure proper functioning. The check may be made by comparing the vibration value measured at any location by the instruments with that measured at the same location by other instruments, or with that provided by a portable exciter.
5 Measurement locations and directions
5.1 Measurement locations
Measurement locations shall be selected on all decks of normally occupied spaces in sufficient quantity in order to characterize satisfactorily the vibration behaviour of the ship with respect to habitability.
In work spaces, measurement transducers shall be especially placed at main duty stations of the crew. In accommodation spaces, transducer shall be positioned in the centre of spaces or where a person stays for prolonged periods of time. In general, measurements should be made at least 1 m from a steel wall as far as practical.
Vibration transducers shall be located and attached properly to the floor surface such that the vibration at the interface between the person and the source of vibration is adequately captured. If the floor is covered with a non-rigid or resilient material, the transducer shall be suitably mounted such that the pressure distribution on the surface of the floor covering is not altered. A transducer mounted on an appropriate three-spike plate may be used. The details about the transducer installation on rigid and soft material shall be clearly stated in the measurement report.
5.2 Measurement directions
The transducer directions shall correspond to the three translational axes of the ship: longitudinal, transverse and vertical.
6 Measurement conditions
Measurement data shall be obtained, in the first instance, during the acceptance or performance trial of the ship. The collection of consistent and accurate vibration data requires the following uniform and favourable measurement conditions:
a) free-route test on a straight course;
b) constant propulsion power according to contractual normal seagoing condition;
c) propulsion rotational speed is set constant during measurements;
d) full immersion of the propeller;
e) all systems to be in normal operation mode [heating, ventilation and air conditioning (HVAC), auxiliary engines, stabilizers, etc. ];and
f) for acceptable water depth needing no shallow water correction, Beaufort scale for wind and significant wave height, refer to ISO 15016.
Any deviation from the above measurement conditions shall be mutually agreed between the interested parties and shall be stated in the test report.
