It was definitely up and down.

Yeah, real gusty.

I'd say it was "episodic." Now I know that isn't a standard sailing term, but it seems to fit pretty well. Each little change in the wind can be described as an episode, like a chapter in a book....

It was REAL gusty.

"Gusty" doesn't even come close. Gusty implies that there were actually some gusts you could sail in.

I actually prefer "aperiodic". It wasn't regular, it didn't come in regular installments.

Hey, that's good! I could deal with "periodic" wind: sail in the periods and rest in the lulls.

Maybe "inconstant" is the word we're looking for?

Naw, that sounds like Shakespeare. It was just real GUSTY.

It was definitely up and down the whole afternoon.

At best it was "intermittent" the whole damn afternoon.

You might say it was "intervalic".

Ain't no real sailor gonna call the wind "intervalic"! It was just gusty.