Help on choosing fuel tanks

[1970Thunderbird]

Hey,

I'm going to install two fuel tanks in my 17' tri-hull, but I don't know which sizes to go with. I'm going to install identical ones, and I figured I'd use two 12 gallon tanks.

If I want to be able to run for most of the day, will 24 gallons be enough? I have a 1978 80hp Mercury on the boat. I'll be using the boat for cruising, fishing, and maybe some skiing. I don't know the fuel consumption for the motor, unfortunately.

So, are two 12s going to be enough? Or should I try to get some 15s or 20s. My only concern is that those tanks will be almost too large.

Thanks!

 

[a70eliminator]

Re: Help on choosing fuel tanks

That's alot of fuel, I have a 16' with outboard 80hp and 2 6gal tanks one in the bow one in the stern both are portable, I have to manually switch them out. There are times I wished I had more fuel, and a bigger boat.
sorry can't give much advise other than take some measurements and go from there, there are many shapes and sized available.

 

[1970Thunderbird]

Re: Help on choosing fuel tanks

How long does 12 gallons last you?

I was going to install both of mine in the rear, and run them together, with a valve so I can alternate between tanks. Or maybe I should just run from both?

 

[a70eliminator]

Re: Help on choosing fuel tanks

About 10mi off the Erie shores using the 1/3rd 2/3rds method with plenty left over, pulling the kids on tubes eats it up but we get tired out before the gas is gone.

 

[1970Thunderbird]

Re: Help on choosing fuel tanks

what is the 1/3rd, 2/3rd method?

 

[a70eliminator]

Re: Help on choosing fuel tanks

It's a practice of using 1/3 of your fuel supply to get out and saving 2/3rds to get back in.

 

[Lion hunter]

Re: Help on choosing fuel tanks

Thats about 150lbs of fuel + tanks in the back of the boat. If you use the 10% of HP rule you'll use about 8 gal/hr at WOT. 24 gals would get you 3 hours apx. at WOT. Are these permanant tanks hooked to fill valves? My old 16' glastron tri-hull w/ a 100hp Merc had 2 10gal tanks. I don't think I ever used it all but it was nice to no it's there if you need it. I run a 16' with a 60hp and 12gal fuel. I'll usually use it all fishing because I run up the lake about 1/2hr, then switch to my kicker which uses almost nothing to troll, then back to the dock. I'll usually have a couple gal left when I get back. If I'm just playing with the kids I'm close enough to the truck that I just carry extra fuel there and fill up at lunch. I like to get out a BBQ and stretch.

 

[1970Thunderbird]

Re: Help on choosing fuel tanks

Lion Hunter,

No, these are portable tanks that I bought at West Marine. I ended up getting two 12 gallons. Anything above that and it got into the permanent tank range and the price easily doubled.