scope:

This NES sets down the philosophy, methods and rules recommended for the design of auxiliary machinery seats in Surface Warships built to noise-reduced standards .

It is intended for use, both in design and drawing offices, by staff who may not have had previous experience of the design of seatings and therefore does not aim to cover every aspect in full detail . Worked examples are given in Annexes A, B and C.

For ships built to noise-reduced standards, the design of seatings is of great importance, therefore both the design stage and the assessment of the completed seat are covered .

An accurate evaluation of the acoustic properties of seatings is difficult and complex and the intended user of the Guide is not necessarily expected to be able to undertake the whole of this task . In this document the emphasis has been placed on features which will in general give adequate acoustic performance .

This NES deals with seatings under auxiliary machinery of all types . It is not intended for use on seatings under Machinery which requires to be kept closely aligned with connected or adjacent items . Seatings for main engines, gearboxes, diesel generators are dealt with as special cases in each new design of ship and so are omitted.

Auxiliary machines are not always minor sources of noise and experience has shown that lack of attention to this aspect of design is a significant factor leading to a 'noisy' ship . In this context noise means the vibration of the structure of seatings which causes significant amounts of energy to be passed into the structure of the hull, to adjacent compartments and particularly to the sea .

While the experience upon which this NES draws has been gained mainly from seatings in engine rooms, that which follows is relevant to the design of seatings throughout the ship.