Are there any rules or ways of estimating wave heights
Well, when sitting down in the AI, close to over your head is probably 3' faces, and double overhead (while seated) then would be 6' faces. (In Hawaii, old style is measuring the back side of the waves which can be a lot smaller.)
More then the height of the waves, is the type of waves. Swells, mostly, are just fun. Gently picking you up, over, and back down. My first time out in overhead swells was scary, and then quickly fun. 8' gentle swells, which put me and a friend on opposite sides, separated by the swell. We could only see the top of each others mast & sail when at the bottoms. Couldn't see land while at the bottom either!
With wind waves, how steep their faces are are a more concern to me than their heights. I run from "hungry" waves!
Also the angle to the waves is very important. Being hit strait sideways by a wave is not nice! rattles the whole boat! I'm sure it's not good for it. And now and again a side wave smacks the captain in the head!
An angle to the wave, to climb, or ride down is nice and helps going over the wave vs plowing through it.
It's easier to show you, than to explain it. When are you "stopping by"?
- - - - - - - - - - - - - - - - - - - - - - - - - - - 2007, 2009 & 2010 Hobie AIs and a 2010 TI