On the learning curve- What's this?

Printing a test piece I noticed a ripple effect in this single pass wall. Its predominantly in the Y direction and X looks great with only a hint of this. I see this in some of my other, larger parts but it doesn't appear consistent. My first thought is its from the marks in the filament from the hobbed bolt but I'm not so sure

I've had this on my solidoodle from day one and even though I print slow and wonder how vibrations could last that long, acceleration control nearly killed this ripple effect.

how do you have your acceleration set.