cooking cane juice

[Ricky]

my friend is cooking syrup thanksgiving weekend and i will have a chance to get some juice. does anybody have a ruff idea of how much juice i will need to make enough blackstrap to do a 10gal rum wash?i know sugar content and water content will be a deciding factor but i didnt want to get 5gal and wind up needing 10gal. i will cook the juice myself and then top off with water to get the sg and volume up. if i have to add cane sugar that is alright but i dont want to use anymore than i have too. maybe some of you old tymers can help me.