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 ?
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