a.) no mention is made of a "breaking" wave, and
b.) it an amateur's recollection of an accident.
but nice try. stew ped, but nice try anyway.
From: (Bryan Glover)
Date: 2/8/2005 12:45 A.M. Eastern Standard Time
Message-id:
Following is from www.seriesdrogue.com
and I scoff and mock all you scared weard little guys,like Jax, who
will no doubt cry foul, because someone with a commercial interest in
this subject dares make a post.
Worst Case Breaking Wave Strike
I have chosen the case of the Winston Churchill in the 1998 Sydney
Hobart race as an example of a worst case breaking wave. The Churchill
was a classic wooden sloop of 25 tons displacement and 55 ft. LOA. Of
the experienced crew of 9, two perished in the accident.
From "Fatal Storm' by Mundle. "A sea came out of nowhere", said
Stanley, " I could feel it from where I was in the aft coach house. It
picked the boat up and rolled it down its face - 25 tons of boat- into
the trough at a 45 degree angle. It was like hitting a brick wall when
we hit the bottom". A crewman below reports that a sudden motion of
the ship picked him up and threw him 7 ft. He observed that 8 ft of
the heavy timber bulwark and planking had been torn off near the
leeward shrouds, and the ribs were exposed. . The boat filled rapidly
and sank in a matter of minutes.
This is an unusual type of accident. Although there are records of
many storm casualties, I am aware of no documented instance of a well
found yacht of the size and reputation of the Churchill and crewed by
an ample group of expert sailors, suffering such catastrophic
structural damage that it sank in a matter of minutes. How could this
possibly happen? The severity or the storm was extreme but by no means
unprecedented. There are numerous reports of large sailing yachts
surviving hurricanes of the same general magnitude. Although yachts
have been lost in such storms I have been able to find no record of
comparable structural damage.
History shows that the probability of a yacht being capsized and
damaged by a large breaking wave is strongly influenced by the
displacement of the vessel. Yachts under 35 ft. have a poor history
while yachts over 50 ft are rarely capsized and damaged.
The nature and extent of the damage incurred by the Churchill is also
most unusual. The vessel was designed by Sparkman and Stevens and was
maintained to the highest standard. Yet the heavy timber bulwark was
shattered, the planking gone and the ribs exposed.
There is no question of the fact that the leeward bow of the boat was
driven into solid green water at an extremely high velocity, far
higher than would be expected in a simple contact with a breaking
wave. We now have a technical understanding of how such a destructive
force can be generated. Observations from many experienced sailors on
a number of the SH yachts provide data which permit a sound
engineering analysis of the performance of the waves and the boats in
the race.
Water forces are applied to the hull of a yacht by two means, buoyancy
forces and dynamic forces. Buoyancy forces are the familiar pressure
forces which keep the boat afloat. They never reach sufficient
magnitude to damage a well found yacht.
Dynamic forces result from the motion of the boat relative to the
water, either as a result of the boat velocity or the water velocity
due to wave motion. A speeding power boat can be destroyed by striking
solid water. Similarly, a sailing yacht can be destroyed if it is
accelerated up to a high speed by a breaking wave strike and then
impacts solid green water in the preceding trough. This is the fate
that befell the Churchill.
To understand this phenomenon we must consider the concept of energy.
A moving car or boat has energy. This form of energy is called kinetic
energy. Kinetic energy is measured in foot-pounds. Kinetic energy can
be calculated by the formula KE=1/2 (w/g) times (v squared). Where w
is the weight of the car or boat, g is the acceleration of gravity
(32.2 ft/sec) and v is the velocity in ft./sec.
Thus a 3,000 lb. weight traveling at 30 m