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

the waterline, or had the bottom edge of the ex-
haust pipe even an inch (25 mm) or so below,
without a problem. You certainly can’t immerse
any standard exhaust more than this. At least
90 percent of the exhaust outlet area mustbe
above the waterline, except for a true underwa-
ter exhaust, which we’ll investigate shortly.

MUFFLER-ABOVE-MANIFOLD SETUP If you

have to install the waterlift canister above the

exhaust manifold, you need to lift the manifold

to get the same 12-inch (305 mm) drop to the

muffler inlet (Figure 7-13). How? Use an ex-

tended exhaust riser for small to moderate

lifts or install an dry exhaust section—very

Chapter 7: Wet Exhaust Systems

Figure 7-12.

Standard waterlift

muffler installation

Figure 7-13.

Waterlift muffler

above manifold exit