fuel capacity on 18?

[Mark]

I had a 1977 18' and the "useable" gallons amounted to about 27! Needless to say, that was removed and a new 50 gallon tank was installed.

I'm not sure how far they expected those inefficient 70's engines to go on 27 gallons, but I would have run out of gas on a daily basis. When I bought the boat it had a 140 V4 Evinrude on it (1986 model) and I would routinely burn through 25-30 gallons a day chasing albies off Cape Lookout in North Carolina.