 The flat main deck with cargo hatches and davits was designed in theory to facilitate the transfer of bulk supplies, however its low freeboard made this work extremely hazardous in typical North Atlantic swells that made the deck awash, so often supplies had to be hand-lifted through the smaller but dryer conning tower hatches to avoid flooding the boat.Resupply and refueling operations often took hours, putting both the milk cow and the submarine it was servicing at risk.If the Germans came under Allied attack during a resupply operation, the milk cow would dive first while the other submarine might fight it out on the surface for a while, as the Type XIV's bulk and flat deck made it slower to maneuver and submerge.