Check the weight table for the different types of cylinders. I belive Catalina cylinders has one on their web site. You might find that a standard aluminum 80 is the same weight or lighter than a HP 80 (only come in steel). Getting a small volume cylinder may be a better bet, plus it is a known fact that girls use less air than guys when diving. So you can dive the same length of time as a guy with a smaller tank.