Archive for October, 2010
a large subtropical semi-permanent center of high atmospheric pressure located over the Atlantic Ocean at the Horse latitudes (i.e., sub-tropic latitudes between 30 and 35 degrees both North and South). When this weather system is located in the Western Atlantic it is referred to as the Bermuda High. When it is located in the Eastern Atlantic it is referred to as the Azores High.
The word for today is Rage – when offshore swell is funneled through a narrow passage or encounters shallow water, causing violent breaking waves—usually in otherwise calm weather. Also known as sea rage. See also: pooped.
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The second post for today is loose luffed — a sail that is attached at its head and tack, but that has its luff free flying and unsupported by a spar or stay. On some sails, such as a staysail, a wire or Spectra line in the luff allows it to be tensioned enough to resist sagging to leeward in strong winds. See also: spinnaker and staysail.
Magic wheel – a purchase system that utilizes a large diameter outer drum coupled to a small diameter inner hub. A trim control line is spooled to the drum. The primary load’s control line is spooled around the hub. Pulling in on the trim line drives the hub at a high power ratio, such as 40:1, 80:1 or greater, depending on the drum’s diameter. Typically used on backstays, but can also be found on other control lines.
a sudden increase in wind speed (i.e., a puff) that temporarily shifts the apparent winds away from the bow. It is the change in vector between boat speed and true wind speed, not a change in true wind direction that moves the apparent wind aft. As boat speed builds, apparent wind moves forward again. Compare to: velocity header.
a sudden drop in wind speed (i.e., a lull) that temporarily shifts the apparent wind more towards the bow. It is the change in vector between boat speed and true wind speed, not a change in true wind direction that moves the apparent wind forward. As boat speed bleeds off, apparent wind moves aft again. A fast bear away also creates a velocity header. Compare to: velocity lift.
Leech return – that portion of a sail’s trailing edge that turns in towards the boat’s centerline; a cupped leech. Return induces drag, and on a headsail, it also causes the exiting airflow to slow down and backwind the main. A small amount of leech return is helpful in light air; the jib will develop just enough power to provide feel to the helm without hurting your pointing ability. Also known as leech hook. Compare to: knuckle.
Warm eddie – a whirlpool of water that has broken off from the main body of the Gulf Stream and that is warmer than the surrounding water. Warm eddies circulate in a clockwise direction and can be up to 180 miles (300 km) in diameter. Warm eddies form off a northward bending lobe (meander) and are found north of the Gulf Stream. Also known as a warm core eddie or warm core ring. Compare to cold eddie.