Hi Carole,
My wife and I are on the cruise before your's which leaves from Barcelona next week. We will be getting off in Venice and staying a few days extra before flying home. Anyway to what I can tell you about the waterbus system in Venice and getting to the ship from the airport.
There is a special class of Vaporetti that makes trips from the airport to the city. It is run by or called the Alilaguna and runs hourly from 6:15 AM until right after Midnight. They make stops at Murano, the Lido, the Arsenale, San Marco and the Zatterre. According to what I can tell the total time of the trip is 1 hour and 20 minutes. There is a second express service that only stops at 3 places, the Fondamenta Nuove, the Riva degli Schiavoni and San Marco. It only runs from 10:35 AM until 6:35 PM. From what I can tell the reguiar Vaporetti don't go to the airport at all. Once you have taken the special water buses to one of the stops above you would then need to transfer to a regular one to get closer to the ship or walk. From what I have heard walking in Venice especially with wheeled luggage is a real problem because of the pavement and the bridges which have steps.
There are water taxis that also will take you from the airport directly to whereever you want to go in Venice but from what I can find out that will cost you from $75 and up depending on how many people and how much luggage.
There are also regular land buses that run from the airport over into the city. and then let you off in the Piazzale Roma where you can catch the regular Vaporetti to go other places in the city.
None of the maps I have of Venice seem to tell me which dock is Berth 107 so I don't know if any of the regular water bus routes go there or not.
The company that runs the transportation services for most of Venice is ACTV. Their website is:
http://www.actv.it/eng/home.php
I have seen some posts on the board about problems getting from the airport to the ship so this should be a topic that should get some other responses.
We elected to pay Princess to get us to the ship in Barcelona and to the airport in Venice. We are going to use that opportunity in Venice to leave our heavier luggage at the airport and then take the water bus back to our hotel in venice which "supposed" to be within easy walking distance of the Ospedale water bus stop.
On the water bus route map in the AAA spiral guide to Venice it doesn't show any stops right at the docks that are right near Venice. The nearest stop seems to be off Vaporetto 71 or 82 depending on which map I try to use.
You might want to check with Princess and see if you can arrange transportation with them from the airport to the ship since I assume they have some special arrangement to get people back and forth.
Have a great cruise. We will try not to "wear out" the ship on our cruise and leave some sights for you to see when you get there.