5-6 mph, depending on where you are
5 mph
5 MPH
An orange circle is used to mark a no wake or idle speed zone.
Slow, No wake speed
15 mph
Per Florida state law, all motorized vessels within that protected zone are to slow to a non wake speed. That means if the speed of the boat creates visible turbulance behind (or "in its wake"), that boat is going too fast.
no wake speed
The maximum speed you may drive in a particular location.
UTC + 12 hrs. (Wake Time)
A no wake speed means the boat is going slow enough that there is no wake behind the boat.
I think it varies from country to country but generally its around 15 - 20 kph.
The maximum speed of a 747 is Mach 0.92.