If you’re paddling a touring or racing kayak, you should stay within 50 meters of the shore.
The one exception is when the water temperature is more than 16 °C, in which case you can venture out as far as 200 meters.
In the harbour
Keep to the right when you’re paddling into and out of a harbour.
A Danish saying goes, “Engines yield to sails, sails yield to oars.” In general, the more manoeuvrable vessel has to yield the right of way to the less manoeuvrable one. It all has to do with good seaman-ship, alertness, respect for others and communicating your intentions clearly.