cruiser. It provides all the advantages listed
previously. Note the plastic (Marelon) sea-
cocks. I often use these in metal yachts
because they eliminate the chance of cor-
rosion, but as we’ve noted, metal seacocks
are required by some class rules and for
Chapter 17:Sea Suction
Figure 17-12. Sea chest seen from outside
the motor cruiser (port grate not yet
installed)
Figure 17-13. Sea
chest profilecommercial passenger vessels under the
CFR. You can also see the suction-line
hoses running immediately to sea strainers.
Many boats do not have a box keel to fit a
two-sided sea chest. A one-sided sea chest
still offers nearly all the benefits of a two-
sided one and can be worked in on most
boats. Note the zinc anode (Figure 17-15).
This should be installed inside the sea chest
on steel and aluminum boats. A sea chest can
also be molded into the bottom or keel of a
fiberglass boat.
These sea chests are all for intake. It can
appear attractive to have an outlet sea chest
for many of the same reasons; however, I’ve
never found outlet sea chests to work all that
well. Taking water from a deep central point
and leading it to where it’s necessary makes
sense, but there can be quite a few discharge
lines. Running them all back to a central
location just about doubles the piping com-
plexity and lengths in the boat. Discharge
will also contain impurities. These can foul
and corrode the interior of an outlet sea
chest. This doesn’t mean you shouldn’t ever
use an outlet sea chest, but it hasn’t worked
out as advantageous in any of my design
work to date.