M_Boats: M-17 rudder depth

Hi Monty owners, one more question I needed to ask: what is the shallowest water the M-17's can sail in? I understand the rudder is not kick up, so I assume that's the lowest part of the boat. I found on the Montgomery web site that the draft with board up is 1'9", which is fine for me, but I wanted to make sure that the rudder is not much lower. Thanks, Andrei.