i have yet to see a boats prop wash to even come close to matching the power of tide and current
http://www.dnr.state.mn.us/water_acc...erloading.html
it might make a differnce on a lake, but around here, thats
I use ramps on a regular basis(couple of times a week), just out of habit(looking for fish) I watch the depth finder while meandering close to the ramp, I'm suprised how many deep holes I find near ramps, with gradual rises back to the "regular depth" as I get further from the ramps