Mainship 36 Fuel Tank Question.

I have a 1986 Mainship 36 and I believe the 2 gas tanks are 120 Gal capacity each. I want to make a sounding stick (graduated dip stick) for my fuel tanks. I am going to use a 7’ long stick of white oak approx. ½” X ¾” and make my marks. The stick needs to be at least 6’-5” to reach the bottom of the tank from the outside deck fill.
Someone told me that they think 1” = 5 gals. But was not sure. Does anyone know the actual dimensions of these tanks? I need to know the length width and height of the tanks. I also am assuming that the tanks are more or less rectangular.
If I can’t find out I will have to do what I did with my diesel tank on my other boat. I ran it dry and slowly filled it 5 gals at a time and marking the stick as I went along. This is not what I want to do. LOL

Greetings,
Mr. B. Rather than a 7' stick which will be fragile, given the dimensions and difficult to store how about a wooden yardstick with a length of line attached? Already marked in inches and you can get by with adding one or two 5 gal cans of fuel just to calibrate...eg: 5 gal=3/4" or whatever.

RT Firefly said:

Greetings,
Mr. B. Rather than a 7' stick which will be fragile, given the dimensions and difficult to store how about a wooden yardstick with a length of line attached? Already marked in inches and you can get by with adding one or two 5 gal cans of fuel just to calibrate...eg: 5 gal=3/4" or whatever.

Click to expand...

When I get a chance, I will give it a try. I started this morning using a tape measure just to see if the 'run' was pretty straight from the "Gas Fill" to the bottom of the tank. There is a slight bend in the line because I had to use some force to get the tape to the bottom. Not much force, but some. This little bit may be enough to prevent the yardstick from just dropping in. Someone else wrote me that they used a dowel jammed inside a stiff hose.

The main reason I want to do this is because next year we will be taking a 1500 to 2,000 mile trip. I would like to hold as much gas as possible and fill up to 2" from the top of the tank. I dont want the gas to sit high up in the fill tube. I'm sure it wont hurt anything to 'overfill' but not willing to bet my life or my boat on it. I never had a gas engine before so I feel it's better to err on the side of safety. I am no more worried about gasoline than I am about crossing the street. I just don't cross blind folded. I have to go out of town tomorrow for 2 weeks so I wont get a chance to check it out till I get back.

My work sched has been crazy this year. I just get home for a few days and I'm off again back to work.

Not sure what your tank access is like inside but on my 34 of similar vintage here's the arrangement. There is an access hatch direclty behind the helm that when lifted gives access to an unused bung on the tank. On the port side there is a corresponding bung but its under the flooring. So there is a 4" deck plate that operates with a 1/4 turn directly over this bung. When fueling I just access these to bungs dip my tanks with a dowel that is marked in roughly 15 gal increments (this is plenty close) When I bought the boat you had to use a wrench to open the bungs but I built some bronze bung plugs with a piece of brass round stock through it and now I can open close them by hand.

I alway try to err 10 gal shy of full to compensate for listing, foam, etc.