The yacht is on a ‘swing mooring’ and will swing with the tide.
This shows us that the water is flowing from right to left.
The perched bird (a cormorant) faces into wind, showing us that the wind is from left to right.
When the wind is blowing in the opposite direction to the flow of the water it means the water will be choppier than normal.
You might also enjoy:
The Secret World of Weather – The Book