Lee wrote:
> Last night I sent some scans (which apparently are too large for the mail
> list server) of the original Evinrude construction process.
I found one of them, and have added it to the "lit" page.
> Here's what the paragraph said of the original construction and foaming
> process:
>
> "Rigid, closed-cell polyurethane floatation (equivalent to 73 life
> preservers) provides additional structual strength. Foaming is done under
> 250,000 lbs of pressure. Closed dies lock the hull in a steel embrace during
> the foaming operation."
>
> "Special foaming machines produce high-pressure foam twice as dense and far
> stronger than poured-in foam. It can't "work" or develop voids; won't absorb
> moisture, shrink. or pull away from the hull regardless of temperature or
> operating conditions."
>
> If you do the simple math that one live preserver could support an adult
> weighing 170 pounds x 73 then that equals roughly 12,410 lbs of floatation.
>
> I think Evinrude was more than meeting the floatation standards of BIA or
> whoever it was reasponsible for setting such standards..
One of the main innovations Ralph Lambrecht (head of the OMC Boat
Division, and a co-designer of the OMC/Johnson 17 hull) wrote about in
his "40th anniversary of the OMC 17 -- a benchmark in boatbuilding
standards" article, published in the July 2003 issue of "Boat & Motor
Dealer" was the flotation;
Not just convenicnces, but safety too
Between the flat interior floor and the bottom were two
fiberglass hat-section stringers with alumninum plates molded
in for the engin mounts, of which there were only two on the
floor for th two-cycle V-4 sterndrive. The upper mounts were
bolted to an aluminum beam running across the inside of the
transom. The stringers were filled with high-density urethane
form, as were all the empty spaces between the floor and the
bottom. Plenty of room was left under the engine, making it
easy to keep clean. The bilge-pump/blower-unit was mounted in
a sump molded into the floor panel. If the water level ever
got high enough to submerge the entire unit, both the pump
and the blower on top of the sealed electric-motor housing
would pump water out of the boat.
The high-density foram in the bottom was mainly for support,
but it also made the boat unsinkable. One of the side
benefits of the OMC 17's unique bottom design was that it
placed a large ammount of foam out in the sponsons on either
side forward. And the deepest part of the foam near the stern
between the stringers, giving the boat three-point boyancy.
The result was that the OMC 17 floated level and upright when
swamped. In fact, every boat that OMC designed in built in
the 8 years they were in the boatbuilding business had this
capability.
You could also leave the drain plug out of your OMC 17 and
stay on board, because there was no place for water to go
under the floor. In fact all five 170-pound people the boat
had seats for could stay in the boat with the plug out, and it
still floated with the hull-to-deck molding out of the water.
This was a safety feature worth talking about. Virtually all
fiberglass boats built in the early 1960's sank when swamped,
or loaded with only their bows out of the water.
Changing the Industry
The OMC 17's remarkable floatation characteristics came to the
attention of the American Boat and Yacht Council, and what was
to become it's Hull Performance Project Technical Committee.
In the early 1970's more than 1,700 people were dying each
year in boat accidents -- mostly in boats less than 20 feet
long. Clearly, the OMC 17 offered some promising solutions to
this trend. One result of the committee's investigation was
the enactment of the "ABYC" Standard H-8 for outboard boats
under 20 feet in length," which required that all such boats
float level and upright when swamped with their rated
passenger load centrally located on board.
This meant that passengers in a flooded boat would only get
wet up to their waists if the didn't panic and they were not
out in big waves. Such boats would also be stable when
inverted, providing a large, unsinkable, and highly visible
object to hang on to. Major boat manufacturers began to
follow the standard voluntarily.
Also in the early 1970'sthe Boating Safety Act was enacted,
empowering the Coast Guard to establish regulations for
recreational boatsq aimed at reducing the rate of boating
fatalities and injuries. The causes of these accidents were
analyzed, and it became apparent that the greatest reduction
could be made by doing two things: increasing the availibility
and use of personal floation devices, and making it possible
for the passengers to stay with the boat, whatever condition
it may be in. The level-flotation requirements of the ABYC
standard were among the first federal safety regulations,
along with a requirement that a PFD be carried on board for
every passenger.
These requirements addressed the causes of more than
two-thirds of the boating fatalities, and were futher targeted
for outboard-powered boats less than 20 feet in length -- the
boats most frequently involved in fatal accidents. The rules
were somewhat relaxed, though, for inboard boats, due to the
difficulty of keeping a boat's stern afloat with an 800-pound
engine located there. Inboard boats were required to only
have "basic floatation," meaning that the vessel would have to
stay afloat, but not neccessarily as a stable and level
platform. At the same time, federal regulations also enacted
standards for the fuel and electrical systems, ignition
protection of electrical components in gasoline engine and
fuel-tank spaeces, positive compartment ventilation and so on.
Thirty years after the regulatory process was initiated, annual
boating fatalities in the United States have declined from more
than 1,700 to about 700.
While it may be a stretch to give OMC all the credit for
establishing these manufacturing standards, it's clear that
they led the way. Someone had to show that it could be done.
OMC produced more than 6,000 boats a year -- mostly inboards
-- in the late 1960's and each one of them had level and
upright floatation. The OMC 17 was the first of that line,
and as such, it deserves our recognition.
(hmm, only the first two columns, and I will have typed the entire
article!)
phil
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Received on Wednesday, 24 August 2005
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