Anthony
Myself and Andy D have managed to attend in 2013 and 2015 but i can't make it next year I'm afraid. If you haven't been before you it's well worth the effort in getting there, talking about that wait until the official site posts a discount offer on the ferry crossing, often around the 20% mark. Your flotilla will no doubt be based at Lamor Barden, nice little place with a few shops, a bar and cafe. Access to the slip is straight forward but very busy if you arrive on the day of the opening procession (best arrive a few days before). The slip does close for the duration of the festival so you won't be able to get the boat out early from this slip if you need to. Many other places to get out if you need to, including a very wide one in the port of Vannes.
Peter