Join Date: Oct 2009
Location: Swarthmore, PA
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Re: sideways on anchor?
I saw a detailed explanation somewhere on why boats "hunt" while at anchor. It has to do with the fact that the boat's center of resistance to air flow is different than it is for water flow. When wind blows past the boat, the center of resistance is roughly at the mast (because it's high and has windage). A high freeboard at the bow can make it even a little further forward.
The boat's center of resistance below the waterline is at the keel, and on most boats this is behind the mast.
Having the topsides center of resistance forward of the keel creates an unstable situation that causes the boat to want to turn sideways when wind blows from the bow. It is oscillating - it will turn to starboard until the rode pulls it back, and then turn to port.
As pointed out here, the solution is to move the topsides center of resistance aft by adding a riding sail near the stern. Or if you have a ketch rig, put up a little bit of mizzen.
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1998 Catalina 250WK Take Five (at Anchorage Marina, Essington, on the Delaware River)
1991 15' Trophy (Lake Wallenpaupack)
1985 14' Phantom (Lake Wallenpaupack)