Chartwork and miscellaneous terms
See also http://www.brighthubengineering.com/seafaring/23602-a-brief-guide-to-marine-navigational-charts/
A COMPASS ROSE (see pic) is a easy means- for a navigator- of finding direction on the chart and also plotting a ship’s course, besides taking bearings (angles) of objects with a compass. Called because it looks like a rose petal opened up, it is graded from 0 degrees to 360 degrees, with 0 being North, 90 being E, 180 being S and 270 being W.
SOUNDING A measurement of the depth of water.
HEADING (HDG): The direction in which the ship is pointing in any instant.
SPEED(S): The speed of the ship through the water. Always recorded in knots (a sea mile is a knot, and is 6080 feet)
Water in motion is called CURRENT. (see pic)
SET: The direction in which the current is flowing.
DRIFT: The speed (in knots) of the current.
COURSE: The direction in which a vessel is steered or is intended to be steered (direction through the water).
FIX The ship’s position, plotted on the chart by celestial or land bearings to a known point. (see pic)
COURSE is the intended horizontal direction of travel measured from 000 degrees clockwise through 360 degrees, where 000 is North.
The Purpose of the COLREGS (Collision Regulations at sea) is to cover, by international convention, anti collision rules any ships belonging to any nationality will follow at sea. Also called ROR or Rules of the Road.