At sea you don't need as much headroom
as your on a wider base handling the movement. I am 6'4" and was quite comfortable in 5'11". It also provided another point of stability by jamming my head against the galley
roof while cooking
and having both hands full. Extra headroom comes with the price
of extra windage and those extra inches are significant. AS long as the bunks are big enough I don't mind too much- I had a hard time sleeping on a Japanese made tuna boat, never being able to strech out in bed
and the bunks were too narrow to lie on my side without jamming against the sides of the bunk.