Originally Posted by foolishsailor
As the energy displacement
effects of a Karman vortex street would extend no deeper than the keel
of the boat generating it and that depth would decrease rapidly as it got farther from the boat? And over 90% of a waves energy is contained in the depth from surface to 1/2 the wavelength of the swell.
So wouldn't a huge portion of the waves energy be out of reach of the surface effects of the karman vortex street?
Yes and no. One good reason for crossing blue water
in a deep full keeled boat.
Second, well yes; the bulk of the waves energy is deep below the surface, but,... it is the surface of the wave you're worried about. That is where the water
driven by the wind overtakes the waves and forms vertical peaks that overrun the waves velocity in fluid, and breaks collapsing down the front of the wave and flips you're boat.
That is the water you need to slow down, so the wave passes under you're boat as a large swell, instead of a breaking wall of water.
So does heaving-to and forming a slick affect deep long period ocean waves?....NO, does it force a breaking wave to break early in front of you, instead of on top of your boat? According to experienced mariners, and fluid theory, yes.
According to Pardey
stalling the hull
by heaving-to, or by sea anchor, (in conjunction with heaving-to), is a critical skill to surviving a storm with breaking waves greater than 40% of you're boat's LOA
. He also stated the tactic you use should depend on your boats stability, characteristics, and strength of storm, wave period, etc...
Running before a storm, was NOT recommended as a storm can increase without warning overunning the boats, (helmsman's), ability to steer, breaking waves on the stern can force a boat beam to the breaking waves and flip you, and you spend more time in the worst part of the storm, and can be driven miles off course or onto a lee shore.
Using a drogue, (off of the stern), while preventing surfing down the waves subjectes the rudder
, and the stern of the boat to breaking waves, it may not flip you, but it may break something.
Using a drogue off of the bow is a sea anchor by another name.... I may have to give it a try. Having 1 device that serves two purposes has several benefits. A series drogue may not be as effective in stopping a boat, as a large sea anchor, but if it helps keep the hull
centered in the slick, it MAY be a usefull survival tool.
If not you can always move it back to the stern.