Feet dragging across the water

I'm regular stance and when I surf a right hand break. While I'm trying to gain speed by going up and down the wave. Sometimes my rear feet that is closer to the tail is slowing myself down. My rear feet is dragging thru the water. I'm not entirely sure what is going on. Is my rear feet too far back on the tail causing the tail to submerge into the water? Perhaps this is where I should be doing cross step and move towards the nose? Or is the lip of the wave hitting my rear feet causing the drag?
This probably occurs 1 in 10 wave that I catch. It's annoying because I'm trying to gain speed but my rear feet is slowing me down. I'm baffled because I don't know what I'm doing that is causing it.
This probably occurs 1 in 10 wave that I catch. It's annoying because I'm trying to gain speed but my rear feet is slowing me down. I'm baffled because I don't know what I'm doing that is causing it.