It would help if you would post the ship you are taking, and what ports you will be visiting.
Don't expect much in the way of USA-type accessibility ashore, but there are resources in some Eastern Caribbean ports. Unfortunately there is not much of this information on this site. You might want to visit the "other" major discussion board for cruisers with disabilities (sorry, they won't let us post the name or URL here). If you can't find it, you can e-mail some of the regulars here as most know about both.