On a friends boat there is an "emergency" fuel shut off on the panel under aft berth near the battery switches. However, this relies on a long cable and a small spring and is notorious for not opening again after use. The valve itself is supposed to be located under the aft berth, I did a cursory exam thru the aft compartments in cockpit and was unable to locate. However I did not look under the mattresses of the aft berth which is the location reported to me later by someone more familiar with the boat.