i've handled canon 70-200 f2.8 IS shooting wake boarding last yr and it was great. but not everyone could handle that weight well, and since you will be shooting on the boat, i would recommand you the 70-200 f4 IS. it's a light weight and considerable good for it's price as well. the 300 or 400 would be only good if u are stable on the ground.
as for landscape, sigma 12-24 or canon 10-22? i would opt for the latter.