Yep. Your boat's foils don't care what speed they're going over ground, only through the water. We've got some strong rips around these parts. They're great to get into as you can use them to get squirted through an adverse tide, but the flow around the rudder and keel is disturbed and things feel bumpy. It's possible that your rudder can even stall momentarily. It's very much like a plane experiencing 'turbulence', but thankfully not quite as 3 dimensional.