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

Chapter 9:Dry Exhaust Systems

Figure 9-24. To allow good airflow, 30 per-
cent of the exhaust trunk (length ¥width)
should be open

not having seawater anywhere in the system

to cause corrosion. To install a water-jacketed

drystack exhaust, you must have this second

raw-water pump and associated seacock and

sea strainer (sea suction, see Chapter 17). In

fact, one way to do this is to install a heat-

exchanger-cooled engine with its full raw-

water system (no keel cooler), but dump the

raw water into the water jacket of a dry ex-

haust and from there overboard. It may be

necessary to have a bypass leading overboard

on the raw-water exit line, as the water-jacket

flow may not be sufficient to handle all the

raw water pumped through such a heat-

exchanger-cooled engine. The seawater in the

Figure 9-25.

Exhaust-ejector

ventilation: cone

“jet” ejector

(Courtesy

Caterpillar, Inc.)