Our old Binoculars on the boat were traditional 7 X 50 (7X magnification and 50mm lens) and they were OK.
Traditionally 7 X 50 is the Marine binocular standard because any more than 7 X and they are too hard to keep steady enough to see clearly on the water. But 7 X is only just adequate for what you want to see and you often need to get closer than you really would like.
In Gibraltar we purchased a pair of Canon 15 X 50 (Twice the magnification) image stabilised binoculars. They have the same bright light lens (50mm) but much more magnification. With the stabilisation they are even easier to use and see through than the standard binoculars.