What is the approximate cost of a 21ft boat rental for a week?
You do realize that not every boat rental agency in the world will charge the same rate nor will every 21 foot boat be the same ( and command the same rental fees )?
Do you realize this is an international web site and nobody here knows where you live and want to rent a boat if you don't say ???? Just another stupid kid question.
call and ask a boat rental office
A lot of money.