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Post: "Heavy Weather Tactics On W32"

12,268 posts on 2,444 threads   •   From Mar 07, 2004 - Jan 08, 2012

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- Archived Message from Inactive Forum -

Norm Rhines

Some extra thoughts
within a wave (near surface)
the uplift; (as the wave is overtaking you) is a flow from the trough to the crest i.e. you have flow past the boat and rudder if you are going in the same direction as the wave.
the crest; this is the top 5% of the wave and is greatly effected by the wind and breaking; this is where the water speed and direction matches the wave speed +/- roughly so this is where a fin keel and even the w32 to some extent wants to turn fall off or change direction. To this end the drogue works well to keep the boat on course as the unit is spread out in waters of all speeds and allows the boat to only pull on those going slower than the boat so there is a very small load increases / .00001Knot increases until you pass the speed of all the drogues in the water (=heavy motoring). The Parachute has a fixed speed of motion because it is at one location in the water thus if you need to move with the wave a little faster the forces become very very big, or are not enough. (This is why it is critical to have the length of line to the chute = one wave length or = two wave lengths exactly)

That said the reason one tries not to go head into the waves was shown on the perfect storm. as you head up the wave the flow in the wave is from behind (less rudder control) then at the top, the bow sees much more flow from ahead, for 0.2 to 0.9 sec before the rudder. So if you are at, lets say 4 deg off near the top of the wave, by the time the rudder sees flow you will be 20+ deg off with momentum = not good.

The other item no one has noted; is the wind loads, at the crests of 20+ foot waves the wind is well, full + strength, but in the troughs it is much much less maybe 10%. so you will need to think about this (just think about a steadying sail at anchor) = I would not put sail up on the bow if I anchored off the bow and like wise no sail up aft if anchored from the stearn. same thought for heavy weather sails.

Bottom Line is, I am with Lee and David on this. Please note: My storm experance is up to 25 footers with 45 to 55 Kts of wind. (we were running 5.5 to 7kts with just the stay sail up) no drogue, heaving would not have been so great as the force on the sail changed by more than 20 fold from trough to crest of the waves (this is not the case in 5 to 8' waves where the wind is some what steady +/-). A drogue would have helped in our case, as we were starting to be pushed off at the crests (speed helped reduce this). I assume in 30'+ waves this becomes even more a problem. Heading into them would have resulted in, you not needing to endure reading my rantings here on the board as I would not be here most likely.

hope this give some insight to rough weather sailing from my point of view.

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