Help with rebuild

[PsyWarrior]

I have a 79 Baja tri-16. It is a 16' tri hull with a 75 hp evinrude OB. I just purchased this a few months ago. This is the first boat I have owned. Unfortunately I know extremely little about the interior construction of boats. (can build a house but don't want to damage anything ripping decking up) The problem I have is that the main decking is deteriorating. I need to replace it. How would I go about removing the current decking without cutting the supports or doing other damage to whatever is between the deck and the hull? any help or recommendations to other sites would be greatly appreciated.