People really don't have much appreciation of what conditions at sea can be like, especially in rough conditions.
Daniel is certainly right about the dredger - if it was too rough to work, she'd stop working, but this looks fine. The fishing boat looks pretty good in this kind of weather, running downwind, and taking the odd sea over the stern. I wouldn't fancy working on deck, cos it would be cold and wet, and a bit dangerous, but fishermen tend to know what they're doing . .
Sinking? No chance.