Scale

I had intended to paint the Cuckold's Lighthouse from the Southport Town Dock, but this huge sailing yacht came by and grabbed my attention.  But how would I show its height?

Placing similar objects nearby or overlapping things will show their relative size.  Without the smaller boats, the size of the large yacht might not be apparent.  Also, the trees give scale to the boat.

It also took some careful and quick observation of the values in the sails because the boat was soon going to be out of sight.  Don't assume value---study it.  The cast shadows made parts of the white sail darker than the sky.