Marcus is referring to the mast rake line on a 14.
14's carry a very
loose rig - you can grab a shroud with your fist and turn it 90 degrees.
When you go downwind on a 14, you go DEAD downwind, so you pull on the mast rake line to rake the mast forward and take the slop out of the rig.
The 16 doesn't need to be that sloppy, but it can still bang around in light air / chop. The creaking and groaning is probably from the boat working in the waves (trampoline frame), not the shock loading on the wires. If your wires are fairly new, you shouldn't worry about it. The only time I've seen the wires pull out of the hulls is when somebody drove their boat into a tree while it was on the trailer with the mast up. It peeled up the front foot of the deck on one bow.