One of the greatest tools I have on board my boat are my stabilizing binoculars. I cannot say how many trips they have made. They have paid for themselves over time.
Anyhow they can be expensive but Defender has some re-manufactured ones on sale right now again.. They seem to sell out quickly when they get them in.
http://search.defender.com/?expression=nikon&s=1
I have the 12x32's which are on sale for $550 (less than I paid) and list for over $1300. They are great even in choppy seas. I can spot birds with them 4+ miles away. Higher power will let you see further but can be tougher to use on rougher days. The 14x40's may be the best ticket but they are a couple hundred dollars more.