Join Date: Feb 2000
Location: Annapolis, Md
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Re: Serious Waves
Neat little video. One of the surprising things to me about sailing smaller boats in big waves is what happens in the troughs. If the waves are big enough and steep enough, there is usually a lull in the wind when you are in the trough that occurs because the wave itself blocks the wind some. Its not a big deal when you are deep reaching or running, but going upwind it can have a profound effect as the boat slows dramatically as it tries to climb the face of the next wave. And then as you get to the top of the wave and are fully exposed to the wind, there is a tendency to knock down.
In very steep wave conditions, I found that it was important to maintain the right amount of speed, and the right angle to the wind. If you go too slowly the boat can actually be stopped, losing steerage, and even be pushed backwards against the rudder. Too much speed and the boat can be launched violently off the top of the crest and come down very hard (especially if you miss a major portion of the back of the wave).
In terms of the angle to the wind, the boat (even on a vane), does not steer at a constant angle to the wind and waves. Talking through the cycle of passing through a set of large steep waves, starting as the boat starts down the wave from the crest....At the top of the wave the boat is exposed to the full force of the wind and so the apparent wind is lifted and the boat heels over aggressively and starts to accelerate as the boat starts down the back of the wave. As the boat moves down the windward side of the wave, the boat speed increases due to surfing, and the wind speed decreases as the the wind is blocked by the next wave so the apparent wind is a header, and the tendency is to fall off to maintain speed and control. As the boat starts to climb the next wave the boat speed decreases and the wind speed also decreases and the apparent wind angle remains roughly the same. But as the boat starts to climb the wave and feels the full brunt of the wind, the wind angle quickly becomes a lift and the boat needs to head up to keep from knocking down.
Because a vane steers by apparent wind, it automatically does some of the right corrections. How successful the vane (or human) will be is dependent on carrying just the right amount of sail. There needs to be enough sail up to keep the boat at speed in the troughs, but not so much sail that the boat knocks down or develops uncontrollable weather helm at the crest. In those conditions a boat with minimal drag for its stability will generally do better than a boat that is high in drag relative to its stability because the low drag/ high stability boat can get by with less sail area and can stand up to its sail area better than a higher drag boat.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay