•intended fuel type- capacity
- tank material and thickness
- serial number
- maximum test pressure
In addition, gasoline tanks must also contain
the note
“This tank has been tested under 33 CFR
183 .510(a)”
If the tank has been tested under 33 CFR
183 .584 at less than 25g vertical accelera-
tions, the statement that follows must be on
the label:
“This tank must be installed aft of the
boat’s half length”
Metal gasoline tanks should be pur-
chased from a qualified tank manufacturer
with the facilities to conduct the full range
of required tests.
All the lettering on a fuel tank label must
be at least^1 / 16 inch (1.6 mm) high and clearly
contrast with the background color of the
label, or be clearly embossed on the label.
Stamping, engraving, molding, and etching are
all acceptable methods of lettering on the
labels, as long as the result is clearly readable.
The label itself must be resistant to fad-
ing, corrosion, or damage by water, petro-
leum products, sunlight, or heat and cold. It
cannot lose legibility over years of routine
use, and it must be resistant to tampering or
modification or show clear signs that it has
been altered if tampered with.Tanks Under Pressure
Several years back, I had a launching delayed
by two weeks. The vessel seemed ready in all
respects when the builder filled the tank only
to find a steady leak—on the tank’s bottom,of course. The only out was to remove the
soft patch. (Happily—if it can be called
that—I’d insisted one be built in, or we’d have
had to chainsaw the deck.) Then we pulled
the tank and returned it to the fabricator.
That tank’s maker claimed he’d run a pres-
sure test, but somehow I doubt it.Tank Pressure Ratings
ABYC and CFR Yacht both require that all
fuel tanks in pleasure craft be able to with-
stand 3 psi (20.7 kPa) of pressure. This is sub-
stantially less than the CFR Commercial
requirement of 5 psi (34.5 kPa). ABYC and
CFR Yacht, however, also require additional
tests such as slosh tests and pressure impulse
tests for gasoline. These are not really prac-
tical for any but large commercial tank fabri-
cators. Accordingly, on my custom designs, I
always specify that the tanks be built to 5 psi
(34.5 kPa) commercial or T-boat standards.
This is the most cost-effective way to come
close to ensuring that a custom or short-run
production tank would meet the additional
slosh and pressure impulse tests. Be careful
in testing tanks, however. If you test a 3 psi
(20.7 kPa) tank to 5 psi (34.5 kPa), you may
well burst it! Check the tank label before running
any pressure test, and if in doubt, test only to
3 psi (20.7 kPa), as no fuel tank on any boat
should be accepted if it can’t withstand this
pressure.
When you’re installing a new tank, it pays
to perform the simple minimum pressure test
required by the CFR—it’s not difficult. A shop
air compressor, standard hose fittings, and
pressure gauge will do the job. Alternatively,
attach a vertical standpipe to the fill opening
(a watertight screw-in fit). Seal tight all other
openings in the tank, and fill the tank and
pipe with water to the top of the standpipe.
A pipe 7 feet (213 cm) high gives 3 psi
(20. 7 kPa), and 11 feet, 6 inches (350 cm)
gives 5 psi (34.5 kPa) of hydrostatic head.
Leave everything to sit for 6 hours. The tank
shouldn’t leak a drop anywhere. If my builder
had done this before installation, he would
have saved himself a lot of work later on.
On larger vessels, an 11-foot, 6-inch
(350 cm) standpipe might not be tall enough.
The design pressure should be 1.5 times the
pressure from the deepest drop from the
highest vent opening. A 12-foot (366 cm) ventPART TWO: FUEL SYSTEMS
Figure 5-15. Tank
label