|Tide at Galle: Note High Tide is around mid day|
In most other countries the tide will change every day and the height too (3-12 feet on average). So before you go out to sea, need to check tide chart for low and high tide times.
In Sri Lanka the time of high tide (වඩ දිය) and low tide (බා දිය) changes very little. To make things even better we have very little difference in height between low and high tide. The difference in tide height is about 0.5 m (1.5 feet) in Sri Lanka.
The reason is that Sri Lanka is one of a few tidal node or amphidromic point. That is center point around which the tides rotate. Think of a string you whirl around while moving it very slightly up and down with your hand. There will be almost no up down (vertical) movement near your hand. At the end of the sting there is a big up down (vertical) movement. The amphidromic point will be your hand, the center of rotation.
For more technical/scientific explanation of amphidromic point see here.