While I think sailing is always a great idea, loosing site of land for the first time in an unfamiliar boat
with a shorthanded crew is a good way to ruin a friendship. I would recommend some sailing courses. I would feel better if you learned enough to handle the boat
yourself for those times when you're friend can't be on deck
. You'll have much more fun if you feel in control of the boat rather than the boat being in control of you. Spending time on other peoples boats is also a good way to learn what kind of boat is for you. Trimarans are not everyones cup of tea and boats are not one size fits all. You might consider joining a sailing club, crew in the races, sail on other members boats. This is an excellent way to sample a variety of boat types.
Things you'll need for your first sail:
sunglasses ( with strap )
deckshoes ( any white-soled shoe )
Things you'll want for your second sail:
personal lifevest ( an improperly fitting vest is almost as bad as no vest at all )
whistle ( attach to lifevest )
sailing gloves ( salty ropes, ugh )
skin lotion ( salty ropes, ugh )
reading material ( sailing is long periods of boredom interspersed with moments of terror )
gym bag ( to put everything in )
Welcome to the forum and please feel free to ask lots of questions.