Which side do you pass red and green buoys?
In the IALA A system, used in New Zealand, Europe and Australia, keep red port-hand marks on your port side and green starboard-hand marks on your starboard side when entering harbour. Leaving harbour, it is the other way round.
What is the difference between IALA A and IALA B buoyage?
Only the colours of the lateral marks differ. In IALA A, port-hand marks are red and starboard-hand marks green; in IALA B they are reversed, so you keep red to starboard when entering harbour. Cardinal and other marks are the same in both.
What are cardinal marks and how do you read them?
Cardinal marks are yellow and black marks placed north, east, south or west of a hazard, and you pass on the side they are named after: pass north of a north cardinal. The two black cones on top show which one it is.
What does a yellow buoy mean?
A plain yellow buoy is a special mark. It does not mark the side of a channel or a danger to navigation, but shows a particular area or feature, such as a racing mark, a speed limit zone, a cable, an outfall or a marine farm. The chart says which.
What is an isolated danger mark?
An isolated danger mark is a black buoy or beacon with one or more red horizontal bands and two black balls on top. It sits on or above a small danger that has navigable water all round it, so keep well clear of the mark itself.
What is chart datum and how do you read depths on a chart?
Chart datum is the level that depths on a chart are measured from, set at about the lowest level the tide normally falls to. The real depth is usually the charted depth plus the height of the tide at that moment.
What are spring tides and neap tides?
Spring tides have the largest range, with the highest high waters and lowest low waters, and come a day or two after full and new moon. Neap tides have the smallest range and come around half moon. Springs have nothing to do with the season.
What is the rule of twelfths for tides?
The rule of twelfths is a rough guide to how the tide rises or falls: one twelfth of the range in the first hour, two twelfths in the second, three in the third and fourth, two in the fifth and one in the sixth.
What is a tidal stream and how does it affect a sailing boat?
A tidal stream is the horizontal flow of water caused by the tide rising and falling: the flood runs in on a rising tide and the ebb runs out on a falling one. It carries your boat with it, changing your speed and course over the ground.
What is a ferry glide in sailing?
A ferry glide is crossing a tidal stream or current in a straight line over the ground by pointing the bow partly into the stream, so that the boat crabs across instead of being carried downstream. Use a transit to check you are holding the line.