Need aluminum gas tank fitting recommendations

[chrisgt]

I'm build an 18.5ft aluminum fishing boat from scratch and I'm looking for recommendations on a good supplier and breakdown of what i need for fittings in the gas tank.
Things I need:
- Fuel fill inlet
- Fuel vent
- level sender
- pickup tube
- maybe other things??

The tank itself is designed to USCG regulations by the designer, but it did not come with any recommendations for how to finish it with all the proper fittings and vents. I have read through the USCG regulations and they are a little bit vague on exactly HOW it should be done. Regardless, I'm looking for a good supply of such parts for when I build my tank.

Since I can't say I'm building a boat without some pictures, this is the boat.

 

[Jeff J]

I would recommend a direct fill tank over a remote fill if it is feasible. Fewer parts make it more economical and easier to maintain. Probably not feasible because it becomes easy to trap fumes in the bottom of the boat even though boats with portable tanks don’t seem to have problems.

I don’t know what drives the need for the hose up to the fill neck other than the EPA’s persistent mission to make life difficult. I have been told if I disconnect and properly cap that hose I would be able to fill my boat without having to trickle fuel into it. Angling the nozzle different directions doesn’t help (I have owned the boat 13 years and have had time to experiment).

It took me an hour to fill one of the Sea Rays at work because the pumps at the dock can’t be trickled. The dock hands frequently let that boat run out of gas on the lake because they think it’s full when it overflows. They don’t verify with the gauge and renters don’t look at the gauge before they depart.

 

[Jeff J]

BTW… cool project!

 

[alldodge]

Agree cool project

You mentioned reading through the requirements, maybe this one with pics can help
USCG requirements pdf Doc

The tank itself is designed to USCG regulations by the designer, but it did not come with any recommendations for how to finish it with all the proper fittings and vents

Not fully understanding your comment
If it was designed to meet Regs than it should be easy enough to determine how to connect

 

[airshot]

You have skills !!!!

 

[Scott Danforth]

cool project

the link in post #4 has what you need. remember the P loop on the vent

 

[chrisgt]

Agree cool project

You mentioned reading through the requirements, maybe this one with pics can help
USCG requirements pdf Doc


Not fully understanding your comment
If it was designed to meet Regs than it should be easy enough to determine how to connect

Thanks, not sure i'd seen that document, or if I did, I'm not good at reading.

Choosing what fittings I want for the fuel fill, pickup tube, etc. is up to the builder; thus my query on the regulations (thank you) and a good source for all these components.
I need to source the fuel fill, the level sensor, etc. I was hoping someone would have experience with tank who would know what worked well and a company they use.

 

[alldodge]

Need the depth of the tank where the float is mounted and where the pickup tube will be. Want a float that is about one inch shorter than depth of tank. Pickup tube about a 1/2 inch shorter

 

[chrisgt]

Need the depth of the tank where the float is mounted and where the pickup tube will be. Want a float that is about one inch shorter than depth of tank. Pickup tube about a 1/2 inch shorter

When you say float, do you mean the one in the Fuel Limit Vent valve? I have also seen fill valves with a float in them to stop the addition of fuel and shut the pump off with the right amount of air space at the top of the tank (those may be newer than this document).

Just curious, why do you suggest the pickup being 1/2" from the bottom of the tank, just so it doesn't suck up debris that gets in over time?

 

[alldodge]

When you say float, do you mean the one in the Fuel Limit Vent valve?

No, the float and sensor inside the tank which is connected to the fuel gauge

Yes so it doesn't pick up debris, the tank will shrink and expand with temp changes. Also the pickup is positioned at rear of tank, bow is up a bit when running, so there is very little your unable to get. Can put it lower but just things to think about

 

[Scott Danforth]

additionally, the inlet fitting is usually 1.5" for gas, and 2" for diesel.

I recommend adding baffles to the tank to prevent sloshing, at least two fuel pickup locations, and a drain fitting should you need to clean it out.

most aluminum fuel tanks are 0.090 or 11 gauge aluminum. all are pressure tested. you will need to follow the USCG requirements on the fuel tank.

 

[chrisgt]

No, the float and sensor inside the tank which is connected to the fuel gauge

Yes so it doesn't pick up debris, the tank will shrink and expand with temp changes. Also the pickup is positioned at rear of tank, bow is up a bit when running, so there is very little your unable to get. Can put it lower but just things to think about

Ahh, makes perfect sense, thank you! I was thinking about having a second pickup for a trolling motor as well; I know you can play games with check valves and stuff, but why not just have a dedicated pickup while it's being built.

additionally, the inlet fitting is usually 1.5" for gas, and 2" for diesel.

I recommend adding baffles to the tank to prevent sloshing, at least two fuel pickup locations, and a drain fitting should you need to clean it out.

most aluminum fuel tanks are 0.090 or 11 gauge aluminum. all are pressure tested. you will need to follow the USCG requirements on the fuel tank.

The tank is segmented into 4 baffled compartments with limber holes in the baffles to allow fuel flow and venting. In automotive fuel tanks I generally put a ring about 3" high around the pickup to avoid sloshing at lower fuel levels, not sure if that's common on marine tanks or not.
According to the PDF in post 4 it is not permissible to have a drain at the bottom of the tank, I was just going to add an inspection port over the center of the baffling so I can reach all 4 sections.

The tank is 3/16" 5052; probably a bit overkill but actually cheaper since it didn't add a whole sheet of 11 gauge to the BOM.

 

[alldodge]

No problem in have more fittings, even extras not used but may use later