(3) SPLS in Engine Room No. 1.

3 engines and 3 generators. Figure 42 gives the

PWL of one engine, and tables 728 and 729 of the

N&V manual give PWL data for a generator. A

3500-hp engine would drive a generator with a rat-

ing of about 2.4 MW. The generator is direct-

coupled to the engine, and would be driven at 450

rpm. Table 728 of the N&V manual indicates an

overall PWL of about 105 dB for a generator of this

speed and power. The PWL of the engine casing is

123 dB (from fig. 42), so it is clear that the engine

is the controlling source and the generator can be

ignored.

steps used to obtain this SPL.

L P = LW + REL SPL ,

Column 2 gives the PWL of the engine casing (from

Part A of figure 42), column 3 gives the Room

where REL SPL is negative valued, as shown in

Constant (from fig. 45), and column 4 gives the

column 4 of table 41. The 3-ft. SPL values are

REL SPL (from table 57 of the N&V manual) for

then inserted in Items 1 and 4 of DD Form 2296

the 3-ft. distance and the various R values of col-

(fig. 4-7).

umn 3. Finally, column 5 gives the SPL, as ob-

tained from equation 53 of the N&V manual,

which is