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

first became popular on the North Sea, a
cold, rough bit of ocean. Everything on these
boats had to work and work well, or they
would be in for serious trouble. Figure 7-15
shows a 42-footer (12.8 m) my office de-
signed with the North Sea exhaust system.
You can just make out the puff of the exhaust
a bit aft of midships at the waterline.

I have to warn you that most of my clients

haven’t cared for the North Sea exhaust sys-

tem, even though they have been very happy

with their boats. They complained that they

did get more exhaust smell aboard and that

they had to wash soot off both sides of the

boat instead of the transom. This has mystified

me. I spent 16 days cruising on three different

boats of my design with the North Sea exhaust

system. I did not experience more exhaust

smell (and possibly less) nor more cleaning of

soot. When I asked the clients about this, they

just shrugged—but they still complained

while happily motoring along. It’s a mystery to

me. Regardless, though the North Sea exhaust

may solve your installation problems, you

should be aware of the operator reaction I’ve

experienced, even if I can’t explain it.

If you follow the height clearances

shown in Figure 7-14 along with the engine

manufacturer’s standard wet-exhaust-line

diameter recommendations, a North Sea ex-

haust will work fine. Remember, the maxi-

mum lift for a waterlift canister (from the

bottom of the canister to the highest point on

Chapter 7: Wet Exhaust Systems

Figure 7-14. North

Sea exhaust system

with waterlift

muffler

Figure 7-15. Forty-two-foot Summer
Kyle/Belle Mariewith North Sea exhaust
(Courtesy Starke Jett)