Another Fuel Tank Question

[rockb]

I am in the process of working on a 1976 18 Chiefton. I say working on because what I am doing in no way constitutes restoration after some of the projects I have seen here.

The fuel tank was shot so I need a new one. I am trying to decide what size. She is wearing a 115 suzuki 2 stroke.

Main use would be running ~20 miles round trip out to the island with the family. I would however like the option of running 10-15 miles offshore fishing so a 40 mile range would be nice. To accomplish this I need some fuel burn numbers. Does anyone here have a comparably equipped Chiefton and could share some numbers?

She did have a tank under the splash well. I'd be open to going with a belly tank if that would help with weight/balance issues.

 

[ezmobee]

Re: Another Fuel Tank Question

Well the commonly used rough formula would have your motor burning 11.5 gallons per hour at WOT. Probably a good bit less than that at cruising speed. Your cruising speed would be about 30MPH I'd think. Then there's some math I can't figure out.......
And I magically determine that you'd want about an 18 gallon permanent tank and a 6 gallon portable as reserve.

 

[GLG fishing]

Re: Another Fuel Tank Question

Sorry I can?t tell you burn rates but the rule of thumb is, 1/3 for the trip out. 1/3 for the trip back and 1/3 for reserve. My boat is very similar to yours and if you can move as much weight forward the better. If you can put a belly tank in you will be happy with the results. If not, I have two Tempo 11.5 gallons under the rear jump seats. It works for me but I wish I had a 25-gallon belly tank.

GLG

 

[rockb]

Re: Another Fuel Tank Question

I didn't realize that the belly tanks were so darn expensive. What makes them so much more expensive than the above deck tanks on a $/gallon basis? Is it just because they are not square? What about the below deck vs the topside? Are they made of a different material? Why can't you put a topside tank below deck?

Popular retailer
$364 28 gallon moeller belly tank ($13/gallon)
$279 27 gallon moeller permanent below deck tank ($10.33/gallon)
$214 26 gallon moeller topside fuel tank ($8.23/gallon)

 

[Mark42]

Re: Another Fuel Tank Question

I didn't realize that the belly tanks were so darn expensive. What makes them so much more expensive than the above deck tanks on a $/gallon basis? Is it just because they are not square? What about the below deck vs the topside? Are they made of a different material? Why can't you put a topside tank below deck?

Popular retailer
$364 28 gallon moeller belly tank ($13/gallon)
$279 27 gallon moeller permanent below deck tank ($10.33/gallon)
$214 26 gallon moeller topside fuel tank ($8.23/gallon)

Any permanent mount tank is expensive compared to a portable tank. So if you are buying one, you might as well get exactly the size and shape that will fit your boat just right. Check out this site where you can search for tanks by dimension, as well as gallons. http://www.oceanlinkinc.com/tanks/gas-diesel.htm

The other option is to check out manufacturers website like Moeller Marine, and pick from their general market tank set, and then search for that model number amongst retailers to find the lowest price.

I know its a pain finding exactly what you want at a reasonable price. Just keep at it and you will find something that works.

Also, don't forget to allocate some funds for new fuel line, fill hose, vent hose and deck plate. That stuff adds up fast.

Also, saddle tanks might be a good choice, as you can put them forward on the boat and therefore prevent the boat from getting stern heavy with the extra fuel.

 

[elkhunter338]

Re: Another Fuel Tank Question

I run a 21' chieftain with a 140hp I/O, I have 32 gallons of fuel on board.
I run 20 miles out for Halibut. I burn about 20 gallons of fuel for the trip with fishing. I burn 2-4 mpg depending on weather. I alway haul an extra 6 gallons.
I would suspect the 115 hp 2 stroke might burn a bit more, but you have a smaller boat. I would say 30 gallon min, 40 would be nice.
I wish I had 40-50 gallons of fuel capacity.