spiral-groove tubing such as Walter’s “turbo
tube.” All these approaches increase surface
area and cooling efficiency to make a more
compact unit provide sufficient heat transfer.
FILTERS/STRAINERS ON KEEL COOLERS
Regardless of the type of keel cooler, it’s a
good idea to install a standard water filter
(sea strainer) in the piping at the exit from
the cooler. This strainer collects any stray
sediment, algae, or corrosion by-products
that may accumulate in the system, and it
thus protects the engine. The filter should be
inspected and cleaned at regular intervals.
KEEL-COOLERAPPENDAGEDRAG Though
keel coolers aren’t appropriate for really
high-speed planing hulls, they can be used
without too much appendage drag on semi-
displacment and even low-speed planing
hulls. Of course, such higher-speed vessels
should have their keel coolers recessed to re-
duce drag.
Walter Machine Co. reports a test of a
boat powered with twin V-8 gas engines of
200 bhp each (see Table 8-4).Chapter 8: Engine Cooling Systems and Their Exhausts
TABLE 8-4. SPEED COMPARISONS
BETWEEN HEAT-EXCHANGER AND
KEEL-COOLED BOATS
RPM Heat Exchanger Keel Cooled2,800 16 .48 mph 16 .40 mph
3,300 20 .85 mph 20 .62 mph
4,000 25 .40 mph 25 .25 mph