- Tide = the vertical RISE and FALL of the ocean water.
- Tidal range = diffenrence between successive HIGH and LOW tides
Spring tides occur when it is NEW moon and FULL moon. Spring tides have a BIG tidal range.
In Darwin that can be up to 8 metres .
Neap tides occur when it is QUARTER moon and THREE QUARTER moon. Neap tides have a SMALL tidal range.
In Darwin that can be as small as 1 metre.
- Semi-diurnal : two tides a day (as in Darwin)
- Diurnal : one tide a day
- Tidal stream = horizontal water flow that results from tides.
- Incoming tide ("flow") = when the water is rising.
Outgoing tide ("ebb") = when the water is falling.
When the tidal flow and wind are in the same direction you have a smooth ride in the boat.
When the tidal flow and wind are the oppositie direction you have a bumpy ride in the boat. So-called Wind-over-Tide.
- To allow for the tides put out twice as much anchor rope as the depth of water plus expected tidal range combined.
So when the water is 3 metres deep and the tidal range is 6 metres, put out at least (6 + 3) x 2 = 18 meters of anchor rope. This ensures that the angle between seabed and anchor rope ≤ 30° at high tide.
When cruising with the tidal flow, travel faster than the tial flow speed, otherwise you lose the ability of steering the boat.