Jig saw... it is a part of boat equipment...
I had it done this summer. I ordered new tank from heater manufacturer and had also heater taken apart and tank replaced with new.Send me an e-mail describing what hold you up. I don't want to make public comment about "in-boat assembly". I know it is a non sense, but you have to remove good 20-30 screws (if not more) before tank is free to move out. Jig-saw will make your life easier.I used it then reworked heater hold-down arrangement. I expect to replace those 30 screws with (2) hinges and a lock next summer.Will use jig-saw again.... what a shame. Jerzy, "Free Spirit".