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There are many
references to drogues and sea anchors in the literature of the sea, going
all the way back to ancient times. For the most part this equipment was
not carried aboard as emergency gear but was jury rigged when the vessel
found itself in dire straits, such as the American privateer David Porter
in the war of 1812. She "took a square sail boom spanned at each end with
a four inch rope, and with the small bower cable made fast to the bight of
the span, the other end being made fast to the foremast, the boom was
thrown overboard and run out some sixty fathoms, the effect was
miraculous. The boom broke the force of the waves and kept the schooners
head to the sea so she rode like a gull till the storm abated." However,
in the days of commercial sail almost all vessels which went to sea were
over 80 feet and of heavy displacement. Such vessels are not very
vulnerable to breaking wave capsize and there are few reported instances
of such disasters.
In the early
1900s, stimulated by Joshua Slocum's circumnavigation, yachtsmen began to
make ocean voyages in small boats. The danger of breaking wave capsize was
recognized and some sailors developed tactics to cope with the threat.
Many of us who spend winter nights on vicarious cruises are familiar with
The Venturesome Voyages of Captain Voss in which he tells of his
adventures in the dugout canoe, Tilikum, and the yawl Sea Queen. He
credits the sea anchor for his survival on several occasions and gives
specific instructions for its design and use. In his worst encounter he
rode the ultimate storm, a major typhoon, for hours with no damage until
finally his riding sail failed, the sea anchor broke away and he lay
ahull. Shortly after he was struck by a breaking wave and capsized.
In recent
years the number of small boats that go to sea has increased dramatically.
Most boats do not carry a drogue as emergency equipment. When caught in a
storm most sailors lie ahull. Some report that the boat rode well with a
makeshift drogue such as 150 feet of 1/2-inch chain on the end of 50 feet
of nylon line. Many report that towing simple warps is ineffective. One
very experienced sailor has developed a system of three drogues streamed
simultaneously: a spinnaker pole and small anchor at 200 feet, two tires
and medium anchor at 300 feet, and two tires and a heavy anchor at 400
feet. He reports that before deploying this rig in a severe storm the
spreaders were driven into the water three times but with the drogue the
boat rode easily.
Multi-hulls
(trimarans and catamarans) are now making numerous ocean voyages. In fact
this type of yacht now holds many records for speed of passage.
Unfortunately a number of these vessels have been lost as a result of
breaking wave capsize. Unlike a conventional yacht, a multihull does not
right itself after capsize. one experienced couple, the Casanovas, has
experimented with the use of a large (24 foot) parachute deployed
from the bow of their trimaran. They report that they have ridden out
several severe storms with this rig.
Despite these reported
examples of successful use of drogues, few boats carry such equipment as
emergency gear. In the 1979 Fastnet race none of the boats were so
equipped. organizations such as the National Yacht Racing Union in the
U.S. and the Royal Ocean Racing Club in England do not require
participants in an ocean race to carry such equipment. There is, however,
the organization, the Royal National Lifeboat Institution, in England that
specifies a drogue as required emergency gear on their motor lifeboats.
They have used the equipment for many years to prevent broaching and
capsizing when running an inlet with breaking waves. They have a firm
specification for the gear and their crews are trained in deploying and
retrieving the drogue.
As part of this report it is
important to consider the question of why drogues have not been developed
and accepted as a standard item of emergency equipment up to the present
time. The following reasons seem to be of the greatest significance.
- Breaking waves capsize is relatively rare, and many sailors survive
storms by lying ahull or by running off. They do not perceive the need
for more gear.
- There is no firm specification for a drogue. When a makeshift
arrangement has been tried it often has not worked and in some instances
has made the situation worse.
- Prudent sailors are aware that a drogue can impose high loads on the
boat. Since they do not know the magnitude of the loads they are
reluctant to take the risk.
- In a survival storm the crew is of ten tired and disorganized. If
the drogue is difficult or dangerous to deploy they are unable to handle
the job.
The research program
described in this report is intended to address these concerns and to
provide the information needed to make a rational
decision on emergency equipment for the prevention of breaking wave
capsize.
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