Given that Haulbowline is a base constrained by basin size and draft we are always restricted to vessel draft less than 4.5 meters. Even that draft at LWS might need an hour of making tide to get out of the mud.
We must NOT get hung up on requiring low freeboard for ease of boarding. An Ocean vessel needs higher freeboard in the forward half-length to reduce wetness and give maximum seakeeping qualities. Water coming on board should not be free to pass aft of the bridge.
Damen have some interesting designs but most are not really tested. Niamh and Roisin have been tested especially the former with voyages to the Far East and circumnavigation of South America. Roisin on the other hand had her Chicoutimi incident in heavy seas. An analysis of these two voyages might trigger a design concept for the ideal WNA capable vessel. Any decision on replacement vessels must always consider our need for MULTIROLE operability