Which is the most important factor in determining a safe vessel speed on any given day?

The most important factor that one should determine in safe vessel speed on any given day is to be made aware of the conditions in terms of visibility. Example of these would be the darkness, rain, mist or fog. Another thing is to check weather conditions and the currents of the water to determine speed for your boat as you head to the water.

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.