The line is actually 'You're gonna need a bigger boat', and is spoken by the character Brody (Roy Schneider) in the 1975 film Jaws. Of course, your line may be from a different film, I'm pretty sure you would be thinking of Jaws.
randall graves (Jeff Anderson) quotes jaws in kevin smiths 'clerks' by saying 'were gonna need a bigger boat' but I think he is paraphrasing a doritos advert that quoted jaws....so there