When active as a ham, forced by the physical / social limitations I had to live with, I found the long wire antenna quite effective. The sole limitation (not a minor one) was the extreme directionality. When at home I had the Pacific and Japan available every night so to speak. Building an antenna tuner was a solution.
When on board, of course, it all depended of the ship's course.
An exceptional experience was triggering a repeater near Rio de Janeiro, coming from the South, two days before reaching the place, that is, around 600++ sea miles away. Our array 2x6 Yagi - 2m band was at the bridge level, some 21 meters above the sea level.
We repeated that performance in many places.
The conclusion I made: for antennas the best ground is the sea.