Forumla for inventory in mulitple spreahsheet

Hi, I need a way to calculate inventory. We have a dive center. Every day on the excel file attached, we create a new sheet for the next day boats. Somes are daytrips, some are overnight. The last sheet inventory need to get deduced the dive equipment which is out at sea. So If BCD columun, M1 is out on boat, it need to be taking off the inventory and appears out. Only BCD, REG (regulators) and Cpt (computers), have numbers. So BCD number is related to size also, M1 (medium 1), S2 (small 2) etc... For mask, fins, etc... just need to inventory the number out vs the number remaining in stock. Also I see the problem is that we create new sheets everyday for the next day, so the formula need to take this into account. Also how to let the formula know, that the boat is back (so equipment back) VS the boat s overnight for 3 days for example. Let me know if you can help.