Section 5 Engine seatings
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Inland Waterways Ships, July 2022 - Part 3 Ship Structures (General) - Chapter 6 Machinery Spaces - Section 5 Engine seatings

Section 5 Engine seatings

Parent topic: Chapter 6 Machinery Spaces

5.1 General

5.1.1 Main engines and thrust bearings are to be effectively secured to the hull structure by seatings of adequate scantlings to resist the various gravitational, thrust, torque, dynamic and vibratory forces which may be imposed on them.

5.2 Seats for main propulsion engines

5.2.1 The seats are to be so designed that they distribute the forces from the engine(s) as uniformly as possible into the supporting structure. Longitudinal girders supporting the seatings are to be arranged in single or double bottoms, and should, in general, extend over the full length of the machinery space. The ends of the girders are to be scarfed into the bottom structure for at least two frame spaces. Adequate transverse brackets are to be arranged in line with floors, see Figure 6.5.1 Typical engine seatings. Small brackets may be required under the top plate in way of holding down bolts.

Figure 6.5.1 Typical engine seatings

5.2.2 In determining the scantlings of seats for main propulsion engines, consideration is to be given to the general rigidity of the engine itself and to its design characteristics in regard to out of balance forces. As a general guide to designers, minimum scantlings are given in Table 6.5.1 Seats for engines.

Table 6.5.1 Seats for engines

Item Parameter Scantlings
Top plates Area for one top plate
A = f (0,088P + 25) cm2
(A = f (0,065H + 25) cm2)
Minimum thickness
t = 0,1A + 14 mm
Girders under top plate Web thickness
t 1 = 0,043A + 7 mm
Girders fore and aft of engine Web thickness
t 2 = 0,01d f + 2 mm
Face plate area
A 1 = 0,1A + 4 cm2
Floors (in way of seating) Web thickness
t 3 = 0,02A + 6 mm

or as that required in Pt 3, Ch 6, 4 Single and double bottom structure, whichever is the greater
Symbols
d f = depth of girder, in mm
f = 1,3 – 0,0003R, where R = rev/min of engine at maximum service speed
t = minimum thickness of top plate, in mm
t 1 = main engine girder thickness, in mm
t 2 = thickness of girders in line with engine seating girders, fore and aft of the engine, in mm
t 3 = thickness of floor plate in way of seating, in mm
A = area of top plate for one side of seat, in cm2
A 1 = area of girder face plate in, cm2
P = power of one engine at maximum service speed, in kW
(H = power of one engine at maximum service speed, in bhp)

5.3 Seats for auxiliary machinery

5.3.1 Auxiliary machinery is to be secured to seatings of adequate scantlings, so arranged as to distribute the loads evenly into suitably designed supporting structure. For larger auxiliary machinery the scantlings of Table 6.5.1 Seats for engines may be used as a guide.

5.4 Seats for boilers

5.4.1 Boiler bearers are to be of substantial construction and efficiently supported by the ship’s structure.

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