Well the Crowley-Beal 28 started out as a day cruiser and fishing boat 50:50. Over the past few years, it's turned to 80:20, mostly fishing. There's no cure for tuna disease. Badly afflicted. We repowered a few years back when the 315 HP Yanmar decided to let go an oil line and now have a 6YL400 in it. It cruises at 18 nicely, tops off high 20's, but get's a bit flaky up there as these boats do. Cruises at 18, runs about 8 Gal/Hr. It has a FG fuel tank right down the center line over the wet keel. The wet keel forms a bump in the middle of the fuel tank forward where the shaft runs through the keel so the tank shape isn't simple. Outside measurements, some estimates, experience underway...the fuel tank is about 75 gals +/-. Stringers on either side of it. Space on port on starboard outside the stringers, but part of this is occupied on port by exhaust. To run S of MV or East of Chatham to fish is about 3 hours at cruise. We have been loading up a 25 gal fuel bladder, a size chosen so I can get it off deck when we start fishing. I'm done with it, works but it's no fun dealing with it ....PIA especially on a sporty day. OK, time to bite the bullet and tear up the decks. I'd like to add 50 gallons. I have the room port and/or starboard. The boat currently lists "slightly" to starboard, and barely drains out the back scuppers, so weight aft would be best. Unwilling to do saddles. Every inch under the wash rails and transom is occupied by gaffs, rod's, live well, harpoon, angler's feet, lee rod holders, and probably something I forgot. Any and all advice appreciated, especially any of you who have added tankage. Seems to me that these boats really like weight aft, so my thinking is put the tanks as far back as I can.