It does appear that Appartamento Casanova is inland, but I think getting to the Rialto stop is the closest you can get. Alilaguna has service from the airport to the Grand Canal (Orange Line) and you can get off at the Rialto stop. You can also take a bus or taxi from the airport to Piazzale Roma and then take the Vaporetto to the Rialto stop. From there it looks to me to be about a ten minute walk. Make sure you have good directions or perhaps they can meet you at the Rialto stop. It is very easy to get lost and disoriented in Venice, but that is all part of the experience. Best of luck, have a great trip.