Paul and All:
I don't have any intell on your tank, but the tank in my Lancer looks like it is galvanized and is a little different looking than your photo shows of yours. Here is a site to help you ID if is is monel or not:
The size, however looks the same. It is much bigger than 30 gal. It is the size of two 30 gal. barrels, so 60 gal. sounds right to me. Here is the formula for determing the volume of your tank, either original or upgraded.
Note that: 1 gallon equals 268.8 or about 269 cu. inches.
height = volume of cylinder or
3.1417 times radius (in inches) squared, times length (in inches) = volume in cubic inches
Determining cost of running depends on which 3 variables you are trying to estimate: the truth, if you are bragging to your buddies on the forum, or justifying the whole thing (or trip) to Janet. i.e.:
Advertised cost of 1 gallon of petrol for a boater with boatitus = apprpximately $3.50. (This is what you tell Janet.)
True Cost (sometimes referred to as the "Denial Cost") of 1 gallon of petrol for a boater with boatitus: (This is what you tell your buddies on the forum)
TC = P + Rf where:
TC = Denial Cost
P = Advertised cost of 1 gallon of petrol
Rf = restoration factor which is equal to ($1,000 times length of boat / number of cu. in. in engine(s) )times 0.10 of average RPM during the time the engine is run for the day or trip.
I hope this helps.
Jerry FILO at the Barmel Yacht Club, where as Rockefella's wife said: "If you have to ask the price of something, you BETTER NOT buy it."