More about Fuel Tanks
by George E. Shilala Jr. CMS
"The letter of
the law, or using common sense".
|Over the past few years I have been retained by
insurance companies to 'render my professional opinion' . My background
and history are in the 'design and construction' of performance
powerboat hulls, structures and power systems. Twice I was retained to
"inspect and report" on a 'leaking fuel tank' in two different 29' Magic
Power Boats. The "Magic Sorcerer" 29' V-bottom offshore powerboat, is
a single engine I/O drive, constructed of 'normal fiberglass hand
lamination' methods. The Magic Power Boat company is located in Lake
Havasu City Arizona. (my home town) Magic is one of eight brand name
boat builders in this town, along with a few 'racing boat builders'
(like myself) here. During the past twelve years, Magic boats have been
sold all over the world, and many have been raced offshore. Within the
past six months the company has suffered financial troubles and are
currently owned by a new group of people. My inspection of both
29' boats showed "the fuel tank aluminum material failed" and that is
what created the "leaking fuel problems". The fuel tanks in both boats
were mounted the same way, in the center, between the main stringers,
not directly resting on the hull bottom, with the cockpit floor bonded
above, and grounded to the vessel's fuel fills and electrical systems.
All of the USCG requirements were met and yet the fuel tanks both failed
without either hull having suffered a grounding or accident. I looked at
the 'aluminum fuel tanks' themselves. (one in each boat) The tanks are
correctly labeled, "82 gallons, USCG, etc.... They were fabricated
in the normal manner, of "5052 aircraft aluminum", the material is .120"
thick due to it's 82 gallon capacity. They were both built and tested by
the same tank manufacturer, and both had NO weld failures. Internal
baffles, along with correctly installed, pick ups, vents, senders, and
grounding tabs, indicated to me that 'these tanks were built to USCG
specs'. I removed the tank from the first boat and found my answer.
During tank installation the "materials and methods" used were not
adequate to control the 'weight and mass' of the fuel tank. Prior to
lowering the fuel tank into position, an installer would "spray a bead
of (2lbs A/B) foam into the hull bottom. Each boat received "an unknown
amount of foam" in a random pattern with no regard for 'minimums or
maximums' of foam material. Compounding the problem was the fact that
the 'fiberglass cockpit floor' is the upper restraint that holds the
fuel tank in place, and it's installed in exactly the same way. The fuel
tank gross weight (aluminum + 82 gallons X 6.5 lbs per = 561 lbs
*approx) is being retained in place by a 'few beads of foam', (or not).
I concluded that the "materials and methods" of fuel tank installation
were not adequate to control unwanted fuel tank movement, and this
'unwanted tank movement' caused the tank to fail and leak. The small
amount of A/B foam beads were being compressed while the boat was in
motion, and continued to compress until the tank became 'uncontrolled'
within it's compartment. On the trailer or in the water, the fuel tank
was being "bounced around in it's compartment, like a toy ball". I did
note that "even with all this unwanted tank movement, the fittings
and all the fabrication welds held without any leaks or failures". "The
fuel tank filler neck and it's welds are intact". I went on to offer
'installation methods used by other boat manufacturers', along with my
findings on this 'leaking fuel tank' assignment. My last point here is
that another "Professional Marine Surveyor" wrote a report on one these
two suspect 29' Magic boats. He was asked to 'report findings on the
fuel tank leaking'. He wrote "the fuel tank is built to USCG specs, the
installation is also to USCG specs". He went on to say: "I can find no
areas were USCG specs have not been followed". "I conclude that the
boat must have been 'abused or misused' at some time during it's use". I
(George) feel our work goes far beyond 'just following the rules', we
must seek the facts. The letter of the law or using common sense ?
George E. Shilala Jr. CMS