What's The smallest boat you've seen 25 miles out?

I have a small 18 ft flat bottom we took out about 10miles last week we were to scared to go any farther. The water was smooth as glass caught lots of sharks but nothing worth keeping. I just wonder what how much larger a boat I need to buy to go out about 25-30 miles and get into some bigger fish. Or maybe i'm just a **** fool for even thinking about that kind of trip in a bay boat what do you think?