Measuring Fuel Level 16 ft Dolphin Super skiff

Discussion in 'Boat Yard Basics' started by Dolphin_Mac, Jan 9, 2013.

  1. Dolphin_Mac

    Dolphin_Mac I Love!

    My 1990 Dolphin Super skiff has an aluminum 15 or 18 gallon tank but Bo fuel gauge. What's the best way to measure and monitor fuel levels to prevent getting stranded? 70 Hp 2 stoke yamaha.
  2. Brett

    Brett > PRO STAFF <

    Dip stick is old school and effective.
    Installing a fuel gauge is a possibility.
    Aluminum tank may be as small as 12 gallons.

    Fuel consumption meters are available, not cheap.

  3. jms

    jms don't let common sense get in your way


    dip stick : only gonna work if there's a straight run from the fill cap to the tank's bottom

    installing a fuel guage-if there's not one installed/this could be a big problem.small aluminum tanks are usually 1/8th" or in some cases -3/16",the area where the sender is located,this area is usually backed up by an additional piece of material - 1/8" of material will not hold threads very well...

    flo scan units are about the best/most accurate flow meters...

    that engine - 70hp 2 stroke-use the 10% rule - meaning,10% is 7 - that engine will burn in the area of 7gph@full throttle - approx half that number @ cruise - 3-4gph...
  4. fsae99

    fsae99 I Love!

    I use my gps, this took some testing and I know when within .5 mile of when I'm going to run out. I do have 2 6g tanks. I would get a 2-3 gallon portable tank and restart my gps trip log then run till empty. Divide the distance went by gallons and then you know how far you can go. I did my testing at WOT so any bit I back off for cruise is + on millage and the + is safety factor (not used in trip planning). You are going to need to either pump or run the internal tank dry so you can find out exactly what it holds if you can not find out any other way. This is so you can determine how far your boat will go on a full tank.

    The stick works fine like Kreepa said. Flo scans are nice since once calibrated you know how pretty much exactly fuel you have used, but just knowing how much fuel you have used is not enough. Boat fuel gauges are not the best in my opinion because you really need to have the tank level to get accurate reading. Again, if you have not measured the distance traveled what good is it.

    I think the 10% rule is for a 60HP and the % goes down as HP goes up. Search fuel mileage on this forum and you find a formula that should get you very close to your actual use.
  5. I have a 1990 dolphin back country and I use the stick method I filled my tank up as full as I could get it and marked the stick then figured half and so on works pretty good when it's calm
    Also to find out tank size you should have a removable wall right behind your tank at the front of your tub just a few screws to pull out and your tank sits right behind it. There should be a plaque on the tank telling you when it was made and how many gallons it holds. Also might want to take a look at your tank just to check the shape of it being that like mine it's 23 years old mine was kinda rough shape but no leaks

    Hope this helps
  6. lemaymiami

    lemaymiami Well-Known Member

    Since I've had bad luck with fuel guages (failing, or inaccurate...) I much prefer a dipstick if the installation will allow it. If you'll look up under the front hatch of many Hells bay skiffs you'll see just that in the form of a 1/2" dowel mounted on spring holders. In my case I've always used a teak stick that's about 3/4" wide by 1/4" thick as my starting point -then sand it down smooth to start...

    Here's how to make a very accurate dipstick (and use a gps to get a very precise read on your consumption....). Drain or empty your existing fuel tank to start fresh then make your dipstick (I like it to stick out of the tank at least six inches when it touches bottom). Drill a hole in one end of the stick if you want to mount your fuel key or deckplate key.... Now it's off to your local gas station. Pump in five or six gallons to start (if you're going to be mixing oil the six gallon mark is helpful -otherwise five gallons....) then dip the tank and using a small triangular file make a starting mark on the stick. Add another five or six gallons then make a second mark (my old Maverick has a thirty gallon tank so you can imagine what it looks like). Once you've topped off your tank you now have the beginnings of a properly marked dipstick - finish it up in your shop by cutting a shallow groove with that same file (and if you're smart you'll make a second stick and store it away somewhere...).

    Now for the really useful part of this exercise. Starting with a full tank, set your gps trip log to zero (most will need their owners manual to figure this out -but once you do you'll want this every day....). Now set out and make a point of running at 75% of throttle that trip for your best fuel economy (roughly 4000 rpms on most small motors). At the end of the day check your trip log, remember the number then re-set it back to zero. Your last step is to top off your tank before putting the boat away. In just two or three trips you'll know exactly how much you burn in ideal conditions. In my case, if I've run 60 miles in a day at 4000 rpm I'll need exactly 12 gallons of fuel to top off. Amount burned divided into distance run = exactly five miles per gallon.... and that's what my 90horse E-Tec burns day after day. With a simple glance at my trip log I can tell exactly what I've burned. That sort of knowledge is very helpfull on long or extended trips - and you'll never need a fuel guage once you've done this routine. Remember, though, you'll always burn more fuel if you're at 90% of throttle than you will at 75%....

    Hope this helps and wish I'd learned to do this years and years ago when I was first fooling around in boats...