Paul, you have hit on a very valid point when building a vessel, that is vessel length verses wave pitch and one of the first questions the owner is asked in regards to the proposed trading route of the newbuild, many a ship has come to grief and indeed there is a vessel on u-tube that snapped in half in the Black Sea because she had been built for Canal operating.
The more local illustration of the problem was with the design of the WW2 Corvette which were designed for Coastal Convoy work in particular the North Sea unfortunately needs must meant they were used in the North Atlantic for which their length was totally unsuitable making their 'A' Gun Crew very wet when at action stations bearing in mind they were not in a Turret and use of the 'Heads' by the Crew subject to Negative G. An increase in the length of the vessel mainly solved the problem although the Corvette was still an uncomfortable Berth for its Crew.
The old Tramps that I sailed on were more of a 'Utility' design bearing in mind their routings were world wide, crossing the North Atlantic in Winter was certainly an experience not forgotten, God knows how they coped going to Murmansk.