Generally, lower power works best in boats. Boats move, even in very calm waters. High power glasses magnify the movement and make it more difficult to see. Most folks stay at 8 power or below on the water. 15X glass are fine on a tripod for bird watchers, but not on a boat.
These work well in a boat...I've used them...but they are not waterproof so you need to store them in a nice case or dry bag and don't use them in the rain. Also, carry an extra battery as they work wonderfully in stabilized mode but poorly in regular mode if the battery is dead.