fuel capacity

new to this, but just had a question someone may be able to answer for me. I bought a 1976 v-20 center console a few months ago, and have not been able to find any real useful information on it. i mainly need to know what is the capacity of the fuel tank on this boat. I have been wary of running out too far, don't want to run out of gas. the 200 merc seems to do fairly well as long as i don't run wide open all the time, i know after going out about7-8 miles trolling for about 4 of 5 hours then coming back, i've burnt about 15 gallons of gas, not too bad i don't think, but i don't know how much is left.