Question

Would like some clarification on the adjustment to ship speed due to 
headwind/tailwind...
 
For example, if our ship is heading towards the south (180 deg), would 
winds impact ship speed on only two occasions, coming from the north 
(360 deg) or south (180 deg)? Winds from any other direction (200 deg, 
340 deg, etc) would NOT have an impact on ship speed?


Answer

You will find the component of the wind in the direction of ship 
movement and figure out if the wind is helping or hindering the
ship movement. The only time that there would be no impact by the
wind is if it is blowing 90 degrees to the direction of ship
movement.