Bow stored fuel tanks, sending unit

R

Rob_F

Active member
Hello,

I've read with interest on the boat builds regarding mounted storage tanks in the bows of the builds.

Curious if anyone has used a portable tank and installed a sending unit/fuel gauge into the portable tank. I found a video of a homemade jobber that used 4-prong boat light adapters. Seemed pretty slick, but there seemed to be a lot of over engineering in getting the float drop to fit the old gauge slot. I currently have a steel tank, but can switch to a plastic easily.

My boat is an aluminum v-hull. To balance the boat better (I seem to hunt by myself much more often), I'm considering moving fuel up front. Not much of an issue with the tank in the bow, unless I decide to put a floor/hatch. I already get nervous trying to decipher how much fuel is "really" left, the floats on portable tanks never seem to give a very accurate description of what's left in the tank, and my Lift/Shake method has left me stranded before [blush]

I currently use a 2-stroke, but anticipate changing to a 4-stroke. Not that having an "E" makes me more safe, but better able to plan BEFORE the tank runs out and I'm in the wrong wind, etc.

This might strictly be an exercise of me overthinking a solution and trying to find a problem for it.

Best,

Rob
 
I have a portable tank mounted in the front of my 16 foot garvey. I don't have any sending unit just a long fuel line. Not sure if that helps.
 
Thanks Brandon.

It does a bit, sounds like it won't have a problem maintaining pressure.

Discovered on iBoats or somewhere, one person using a digital flow meter to keep track of fuel consumption. everything I'm finding for that is $150 and up. Components to mount a gas gauge and connect a float are about $60.

I'll figure it out. Again, I may be over thinking the solution to fit the problem. Might be better thinking about it like Lukenbach... just get back to basics....
 
Rob,
Since it helped Ill give you a bit more info.
I just have a 12 gallon portable tank on a shelf in the front of the boat. Its held in place with two bungie cords and the shelf itself is designed to hold it. I can no check the fuel level all that well but I keep an extra couple gallons in another tank as backup. Generally I don't have an issue with fuel levels I don't run that far.

Anyway I probably have 20 feet of line in the boat. I just pump the ball one time and the beginning of the season and that's it. I am running an older 40 2 stroke evenrude. Oiler is bypassed and I mix 50/1 in the tank.

Good luck.
 
If you just want an accurate check before leaving home, use a simple dipstick. Make you own custom dipstick and calibrate it to match the fuel level in your tank. Start with an empty tank in the boat, with the boat in the position you want it to be when checking the fuel.

With everything in position;
(1) add a gallon of fuel.
(2) let it settle.
(3) check the fuel depth with your unmarked dipstick.
(4) make a permanent mark on your dipstick indicating one gal.
(5) repeat by adding one more gallon
(6) make a mark indicating two gal.
(7) repeat as needed

Now you have an accurate fuel level indicator for your tank that can be used before your venture. Doesn't help much while on the water but it may be better than the lift and shake method.
 
Here's my situation:

I am very fortunate to have access to a duck camp where I can leave my boat. From the time I arrive to motor on the lake can happen as fast as 15 minutes. The location is not ideal for pulling a boat to get fuel, so you bring it down OR take the tank with you to fill.

As I currently run 50:1 2-cycle, I tend to prefer to take the tank with me so I can measure fuel/oil more accurately.

Right now, the 6 gal tank resides at the stern by the motor. But I'd like to move it up front. Maintaining line pressure is one concern, but similar to you, I haven't had to pump the bulb since hooking things up a few weeks ago.

With the tank in the bow it will only be a slight annoyance to walk across seats or go "monkey" off the dock and jump in the bow, it's only 14', but decoys, blind, etc always seem to complicate EVERYTHING. I like space to have a purpose.

I'm contemplating some customization to the boat (AlumaCraft F7), which would include fuel and battery storage compartments in the bow created by decking over the third bench and the wee little bow seat. This area would also get some flotation foam, anchor, and line storage. The rear, currently clogged with the gas tank, would receive dry storage compartments with extra flotation.

My general concern is: once "out of the way", an already difficult to gauge task (how much run time do I have left on the tank), feels like it will more easily be missed. Half the time it's all I can do to remember the plug. Since the boat does not leave the camp, and there is no visual or audio reminder of "fuel tank", I'm thinking some sort of redundancy in an already learned behavior (checking the car fuel gauge), will be beneficial.

Other work that would coincide with this would be mounted navigation lights, dry storage w/ compartment lights, accessory plug for charging portables and running depth finder. I envision a panel with a couple light switches, battery meter, and fuel gauge.

The goal is to go from my 1987 Kikhafer Mercury 110 (9.8hp) to a 20hp Four Stroke (boat is rated to 25 hp, but the engine block weight goes up significantly after 20 hp). Going to Four Stroke maybe makes the fuel easier, as I'm in MN and once the duck hunting is done, the water gets really, really hard for about 5 months and fuel will sit in the tank. I'm an experienced Sea Foam and Stabil user, but I prefer to empty the tanks on the mixed fuel rather than run "old gas". Maybe this is a misnomer as well. All my 2 stroke get non-oxygenated fuel. At a minimum, I could pull the 4 stroke, non mixed gas out and put it in my 25:1 snow thrower.

As often gets mentioned here, the question may not be as much "why", but "why not?". The issue at hand is comfort AND safety! Surely a justifiable combo if there ever was one!
 
Not sure if this will help with your idea much or not, but here's how I set my fuel tank up on the boat I built this summer. The 6-gallon tank is under that hatch on the front deck, the bulb is by the tank where I can reach it from the cockpit and it feeds back about 15' to the 35hp mud motor. No problems with fuel flow whatsoever, and I can check the tank gauge and refill the tank through the hatch in the front deck. The front nav lights and spotlight bar are wired to the main switch panel in the rear of the cockpit that also has a 12v socket and usb/voltmeter.
MCUvNEd.jpg

 
Rob, If you need a 4" hatch cover, give me a PM and I can get you one or more of those. That's what I did on my Broadbill.
 
Capt J. Stieben said:
Those that have moved the tank to the front are u mounting the pump ball up front for a reason or can it be in the back?
Click to expand...
I put mine nearer the tank because it seems to me that it's easier to push fuel through the line to the motor than pull it all the way from the tank to the engine. It might work either way but putting it closer to the tank makes more sense to me.
 
It probably will work either way but what has to be considered is how the fuel system works. If the primer bulb is in the back atmospheric pressure is what pushes the fuel through the line to the fuel pump. The primer bulb is only used to fill the fuel line when the engine is not running. If the primer is next to the tank you can really build pressure in the line. Most people have the impression that the fuel pump "sucks" the fuel from the tank when what actually happens is atmospheric pressure pushes the fuel into a partial vacuum created by the pump. Lesson over.
 
So, similar to a siphon, the less gravity to overcome the more effective the vacuum at moving the fuel from the area of higher pressure (tank), to the area of lower pressure (the fuel pump).

i.e. if putting the tank in bow and the pump in the back, better to keep the hose at or below the low fuel mark on the tank for as long as possible. Then, a quick pump or two to pressurize the line from bulb to fuel pump. Once motor is started, the centrifugal force from the pump creates pressure low enough to "suck" the fuel up the last vertical foot or two.

And this is why a gap in the line or at the fuel pump connection won't get an outboard to run, the motor runs poorly on choke, and they put an arrow on the bulb that some people can never quite grasp :)

Upshot: run tank hose along lower portion of gunnel, not tucked up top?
 
Close but not quite, the fuel pump is not centrifugal. That would be the water pump. Only time anything "sucks" is when it doesn't work. That last little bit up the fuel line is still atmospheric pressure (14.7 p.s.i. aprox.) pushing the fuel all the way from the tank. I suppose ideal would be level as possible but I have run 12 ft. up, down whatever. You are right on the loose connection problems, when pressure inside = pressure outside nothng moves. class dismissed.
 
Well, now I have to break into my motor and see!

Had an issue with my '79 Merc 80hp that ended at the fuel line/pump connection..... my brain's voice says, "looks like da vater pump in dere..."

Trust me, and you would have learned this if the MacQuarrie journey would've happened: my brain is, interesting.

The motor connecting in the current use is a '68ish Kiekhafer Merc with Thunderbolt Ignition.... it's like a 1960's Super Hero or something :)

I scoped the pieces to make things happen. I can get aluminum rectangle tube for <$50. Challenge will be the flange units I want.

Gas will run approx 12' hose, bulb at back. Hatch for fuel/storage in bow will be 2 compartments: battery/storage one side, fuel/storage the other side. Dry boxes with flotation at rear, parallel to gunnels. Remove 2nd bench and support with aluminum rectangle tubing.... Netting or plastic fence to provide storage containment and plywood top for shelf space.

I love it when a plan comes together :)
 
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