My own personal preference is contact cement.
Reason being if you have to replace carpet again with the regular carpet glue you have to grind and scrape the stuff off.
I didnt my first carpet job with regular glue on my boat and its nice but I repalced some pieces on my boat as well and had to grind the stuff off. used contact cement and it holds just as good and looks just as good.
Good Luck its hard work either way. make sure you prep it good so it comes out nice.
I guess if I had to do it again I would let someone do it for $800-$1200 thats what I got quoted for an 18 foot ranger.
Delw