Dave Gerr - Boat Mechanical Systems Handbook-How to Design, Install, and Recognize Proper Systems in Boats

PART THREE:EXHAUST SYSTEMS

Figure 9-3.
Expansion slip
joint

stainless pipe of the diameter required to meet

the engine manufacturer’s specifications.

Alternatively, a flexible bellows may be

used instead of the slip joint (Figure 9-4). Note

that the expansion slip joint is not completely

vapor tight. It should be used only in locations

where the ventilation air will clear any possi-

ble fumes. This means high up on the exhaust

stack. Lower down or in the boat hull and

cabin spaces, bellows should be used.

Keeping Water Out

To keep rain and spray out, the open end of

the exhaust outlet is cut off at approxi-

mately 15 degrees past vertical as shown in

Figure 9-1 and equipped with the three drain

slots as shown in Figure 9-5.

Fastening to Accept

Expansion and Contraction

Keep in mind that the exhaust piping’s tem-

perature will vary from as cold as 10° or

20°F (−12° or −6°C ) or less, to as hot as

Figure 9-4. Slip joints or stainless bellows

allow for expansion

Figure 9-5. Drain slots (Courtesy

Caterpillar, Inc.)