Hi! I am using La Barcaza party boat for my wedding reception on May 9 2011. I'm so excited
You do have to take a small speed boat to the party boat because obviously a big boat like that can't just come up and park on the shore. It looks like it can seat quite a few people at a time. A friend of mine used the boat for her reception (hence where I got the idea from) and she didn't mention any problems that people may have had getting off the motor boat and on the big boat.
If it is the boat you are talking about in regards to making reservations for 8, you can make reservations on the regular La Barcaza restaurant boat for as many or as few people are you like just like a normal restaurant. If you want the wedding boat all to yourself there is a minimum of 20 people required. I believe that you can have as few people on it as you want, but you still have to pay for a minimum of 20 people. Hope this helps!