Best method to Line Out a second planking?

[Philski]

Thanks for all the helpful information in this thread.
One question: what do you do with the divider if it is not an exact number of planks on the widest point, but lets say 15.5 planks?

well then how's how is your math? take the span and divide it by 16.....each plank would still be the same width, making up the difference of that half-plank.