Under deck fuel tank fitament

[mitchp]

I have a 14 foot closed bow runabout. It has two for/aft seats and can carry two adults and two childern. The boat came to me equiped with a 35 HP OB, with no fuel tank or fuel lines. I would like to install a 12 gallon underdeck fuel tank in the space under the covered bow. This sure would look nicer than one or two portable fuel tanks as well as opening up valuble space in this size of a boat. If i install this tank will the weight of the tank and fuel adversly affect handleing and the ability to get the boat up on plane? How would you set up the fuel lines? I notice that portable fuel lines with the squeze bulb, are only availble in lengths of 80 inches. would i be installing automotive style metal fuel lines? When it comes to fuel systems safety is the highest priority, next is a very clean installation. Thanks in advance. Mitch

 

[Bondo]

Re: Under deck fuel tank fitament

If i install this tank will the weight of the tank and fuel adversly affect handleing and the ability to get the boat up on plane?

Ayuh,... More than likely,.. Yes....

Bulk fuel line is available from most retailers...

 

[steelespike]

Re: Under deck fuel tank fitament

We had a 15ft Starcraft Nova closed bow. We added a 12 gallon steel tank under the bow.It actually improved hole shot and ability to stay on plane.It moved the weight from the stern to the bow.I think I would have someone or something ride up under there to see how it acts.
You will need a filler in the deck also need a vent over the side.

 

[mitchp]

Re: Under deck fuel tank fitament

We had a 15ft Starcraft Nova closed bow. We added a 12 gallon steel tank under the bow.It actually improved hole shot and ability to stay on plane.It moved the weight from the stern to the bow.I think I would have someone or something ride up under there to see how it acts.
You will need a filler in the deck also need a vent over the side.

T hanks steel. I guess i will start with a small portable tank for testing, then add 128 pounds of weight under the covered fordeck. Hate to waste money on a portable fuel tank just for testing. I think the ultimite set up would be two narrow 6 gallon tanks located under the gunnels on both the port/starboard locations. Im a sheet metal worker, and was wondering if i was to fabricate my own fuel tanks would this be legal? From what ive read my vintage Evinrude 35 is a thirsty beast. Man, im a vintage motorcycle racer/restorer. Now my intreasts have to turned to boats. Back to school Mitch. Thank all you I Boat responders for helping with my many inquires. Mitch.

 

[steelespike]

Re: Under deck fuel tank fitament

Use what ever tank you have just don't fill it for testing.In good tune your 35 will use about 3.5 gph(gallons per hour) at wot(wide open throttle) Obviously less at cruising speed.
What year is the motor? Also if you fine tune your setup for best speed you can save a little fuel by getting from here to there faster.

 

[mitchp]

Re: Under deck fuel tank fitament

Use what ever tank you have just don't fill it for testing.In good tune your 35 will use about 3.5 gph(gallons per hour) at wot(wide open throttle) Obviously less at cruising speed.
What year is the motor? Also if you fine tune your setup for best speed you can save a little fuel by getting from here to there faster.

The OB motor is a 1959 Evinrude Golden Jubilee 35 HP. Its a 2 cylinder 2 cycle engine. I have now been advised to locate the fuel tank very close to the motor for good fuel flow. From your GPH estimites a 6 gallon fuel tank with a second gas can would be about right. What do you think? If i get this motor running well, is it a viable powerplant, or should i look to getting somthing a bit newer? Thanks Mitch

 

[steelespike]

Re: Under deck fuel tank fitament

These motors are rugged,simple and reasonably powerful if a little thirsty.They have a plentiful supply of new and used parts some right here at iboats.The basic design started in the early 50s
and the present day 2 cylinder Evinrude Etec is a sinilar very refined developement.
More obscure parts are available at well established BRP dealers and many vendors across the country.There is no need to place the tank close to the motor if the fuel system is healthy.I think 59 is probably a single line tank.
If you think about it underway a bow tank is probably close to the same level as the motor.
Distance from the motor is no problem for a healthy system neither is height within reason.
Is it a big Twin or a Lark? Weight ranges from about 125 to 138 lbs.about 100 lbs lighter than todays 40 hp Etec.Top stock speed on a reasonably fast boat is about 33.

 

[cr2k]

Re: Under deck fuel tank fitament

If you feel you may have fuel delivery problems you can increase the fuel line size to 3/8 or 1/2 from the tank to the motorwell, where you would attach the flex line and primer bulb. There will be some friction loss in the delivery thru a long line as you will need. Steel is good, do not use copper as it tends to crack under vibration. I don't know what the USCG has to say about home built tanks but if properly constructed they should be fine. Building them yourself would also give you the opportunity to coat the insides for lasting protection.

 

[steelespike]

Re: Under deck fuel tank fitament

I've had 2 bare bones 18ft utilities. I placed the tanks at the bow on both boats I simply ran a length of factory size NAPA supplied line right down the middle through the relief holes in the seat bulk heads.line lasted close to 20 years never a supply problem on the original much used 25 Gale,a 65 Merc 500,77 Merc 500,and an 88 Evinrude 50.Also ran a line down the storage shelf along the side of a 15ft Starcraft Nova.Same line for 25 years.It was protected from sun by the storage shelf.
You could do something similar,you may have to figure a way to secure it I didn't have that problem.

 

[mitchp]

Re: Under deck fuel tank fitament

Thank you for your reply. Ill have more inquires as i progress. So far all i know is its a Evenrude Golden Jubilee 35 HP 1959, 2 cycle twin cylinder motor. Its great to know thats parts are still availble. Now to find a local dealer???? Mitch

 

[mitchp]

Re: Under deck fuel tank fitament

Thanks, not sure what Bondo was talking about in the handleing department. I will procede with the installation of a 12 gallon under deck fuel tank with flush mount tank filler mounted on the fore deck. Cool. Mitch

 

[mitchp]

Re: Under deck fuel tank fitament

Thanks for the infomation, as well as your encouagment. Not sure if i have a big twin or Lark. I will check into I boats parts store, first and formost to obtain a manual for my OB. Im also curious about what fuel to run thru this engine. Back in 1959 there was no unleaded gas and octane ratings were very high compared to todays ratings. With the support of all you good people @ I Boats, This boat/motor will live again. Thanks Mitch

 

[Bondo]

Re: Under deck fuel tank fitament

not sure what Bondo was talking about in the handleing department.

Ayuh,... My only point is that 12 gallons of gas, plus the tank is pushin' 100lbs., 'n that little motor make lack the power to lift it onto plane,...
Or at the least, it'll possibly be bow heavy...