M_Boats: shallow water

Folks, As an ex-Potter sailor with a 17, I just can't seem to give up the desire to pull into a sandy or muddy beach and jump off for a stroll. I hate to bring this up again, but I am wondering if sand or mud will inevitably jam the centerboard if I come in until the keel touches. Anybody actually tried this, and what happened? Bob has a picture of two 15s on his Montgomery website doing just this, but I don't know how different the keel and centerboard arrangements are. Finally, if the centerboard should jam with some debris, is there any way to pull or push it down without swimming upside down with a pry bar? Thanks, Tom Jenkins M17 #626 Scintilla