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From: (no name) (no email)
Date: Fri Jul 16 2004 - 08:58:54 EDT
In a message dated 7/16/04 12:05:46 AM, Arild writes:
<<
The one use I have not seen mentioned and which might be most relevant to
river running is as an emergency brake.
In the Great Lakes all the freighters specifically designed and intended
only for St. Lawrence Seaway use all have full sized anchors mounted on the
stern. Located on a ramp for quick deployment.
This is to be used in the event something goes wrong with either the
steering or the propulsion while going downstream.
In many places the river current is as much as 5 knots during spring
freshet.
Dropping a bow anchor may not be a viable option since doing so would result
in the vessel first being pivoted broadside to the current as the bow is
stopped and the stern continues to over run the anchor position. >>
Very good point!
Worldwide at least one ship a day is lost because of impact with another
ship, shore facilities, or the ground, most in shallow water at harbor approaches.
Given the preponderance of flammable and/or toxic cargos, the risk to
inhabited areas and the environment is very high.
Twenty-five years ago I was a consultant to Marad and the Marine Board of the
NSF and director of a project devoted to minimizing collisions, rammings, and
groundings.
One conclusion of the study was that ships should be equipped with emergency
retarding devices, i.e., anchors, which could be depended upon to halt the
ship within a few boat lengths. Our engineers even came up with a feasibility
proposal which consisted of a large, wide fluke Danforth like anchor which would
be driven into the bottom by rocket assist devices. The rode was a 12 inch
diameter nylon rope with a breaking strength of about 2000 tons. The elongation
of the nylon rode under tension would minimize anchor breakout and failure of
the mechanical attachment to the ship. Each ship would be equipped with several
units, depending on ship size, fired by remote control from the bridge.
Computer simulation showed that in the shallow harbor waters, depth less than 100
ft, most ships could either be stopped or the course diverted sufficiently to
avoid collision.
The proposal was not adopted for political rather than technical reasons. US
flag ships were carrying a diminishing portion of US maritime trade and Marad
was afraid any additional requirements would cause the few remaining US
carriers to transfer ships abroad. Since the USCG could not enforce regulations of
foreign flag ships outside of US waters, it was felt that the overall increase
in maritime safety would not be significant.
Anyway, since completing the study, I've always kept an emergency anchor and
nylon rode at the stern of my boat, right near the steering station, in case
of a power failure or potential collision emergency.
Larry Z
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