near the tank bottom, once again, isn’t nec-
essary for a diesel tank, but it costs little and
helps isolate the fuel in the tank and reduce
foaming—both well worth doing. Fills
extending this far down into the tank must be
supported structurally at their lower end to
prevent stress cracks from vibration.
Another common source of leaks, by the
way, is at the joint between the fill cap flange
and the deck. Vibration and weathering can
destroy the sealant or bedding compound,
allowing spills at fuel-up to find their way
below. Check the boat carefully. You should
also make sure that spills can run or drip over-
board easily and absolutely cannot get down
into the boat. Fills must be at least 15 inches
(38 cm) away from any opening into the hull.If you’re installing hose from the deck-
fill fitting to the tank, it’s a good idea to have
about 8 inches (200 mm) of pipe directly un-
der the fill. This way, years of repeatedly jab-
bing the fill nozzle into the fill won’t abrade
the hose, yet another potential source of
leaks over time.
Antipollution laws are a real poser with
regard to minor fuel leaks. These laws forbid
anyoil or fuel spills into the water, while at
the same time, safety regulations forbid any
spills into the boat. (I wonder where they
expect spills to go?) Obviously, some small
spills and drips are unavoidable, and you
can’t have them run into the boat or you
would have a very serious fire hazard. The
only solution for the moment is to make
certain that those few, unavoidable small
spills do go overboard and hope that the
policing agencies are reasonable. So far, I
know of no cases of the Coast Guard or har-
bor police ticketing small, unintentional
spills from boats, though it appears they
could do so.The Vetus Splash-Stop
Vetus offers its Splash-Stop unit (Figures 5-10
and 5-11), which is basically a vent collection
tank combined into the fill-cap assembly.
This gizmo addresses both the expansion and
fill spill problems noted earlier, and it is avail-
able for both 1^1 / 2 - inch and 2-inch (40 and
50 mm) hose.Seacurefill
Another approach to controlling spillage
during fueling is Seacurefill (Figure 5-12).
This unit is a vent assembly with a built-in
fitting for a clear hose with a quick-
connect device to the fill. During fueling,
the vent and the fill are opened. The clear
plastic hose is fastened into the vent fitting
and led in a U down into the fill pipe next
to the fill nozzle. When the tank tops off,
the nozzle’s pressure switch clicks off, and
the clear hose fills with overflow that’s di-
rected back down into the tank. This is a
clear warning of a full tank, and there are
no spills.PART TWO: FUEL SYSTEMS
Figure 5-8. Vent
collection tank
(dimensions can
be modified)