Our boat came with 4 hard tanks and I added 2 more on top of the rear stock tanks.
We ran that for a couple years but realized we needed bags to get the weight needed.
Below. rear tanks. there is another one underneath plus two more under the seats.
The bags. Rear ones are notched to fit over the side swipe exhaust plumbing.
I boxed in the exhaust plumbing and valves with panels made out of Celtec expanded PVC. Made some templates out of cardboard and then cut the pieces. This allows the bags to be bigger and sit further back. The fore/aft bulk head on the right has the aluminum channel that the new side panels will slide into.
I also made bulkheads to constrain the inside of the bags under the seats. My daughter made the templates and then I digitized and CNC'd the Celtec parts. They were basically the same on both sides so that saved some time making them. The rear edge on the left will get the forward channel for the engine side panels.
Starboard bags installed and new engine side panel. CNC'd these too. Corrugated hose is for bilge fan. Hoses to tanks are for venting. Fill and drain ports are on the bottom towards the back.
Hopefully a forum update is coming so my photos can show up inline. Until then here is a video of our wave after the bags.