[Scott]

Well I’m guessing you have 4-5 baffles in that tank. So if they are all 1/8” thick that’s approximately ½”to 5/8” of space occupied by the baffles. I have been told by the builder here that 1” of tank length will buy me a bit more than a gallon capacity using 28” as the width and 12” as the height …So those baffles are taking up very little volume.

As far as your tank goes I certainly would think you should have more than a 100 usable gallons in a 154 gal tank. That’s a 1/3 of your capacity. That’s about 4” of fuel, 50 gallons, left in the tank when the boat is at rest or the tank is level (if the fuel pickups were that far off the bottom of the tank) and unless the boat is bow heavy causing fuel to pool forward away from the pickups.

What are you basing the useable volume on ?? That tank has such a huge surface area that its probably tricking your fuel gauge …each 1” of fuel in that tank is about 12-12.5 gallons. Do you have a fuel flow meter?