Marking a Dipstick

    Due to the tapered shapes of boat tanks, dipsticks almost never give a direct proportional reading (i.e., halfway up a dipstick is not a half-full tank).  To mark a dipstick, try the following:

Fuel tank:  

A) Using a separate pump from the engine fuel pump, transfer fuel from the tank to be marked to another tank until you:

1)	reach the bottom of the fuel pickup tube or
2)	reach a level that you would consider minimum useable fuel level (small heeling angles might cause a dry suction beyond this level)

B) Fill the tank in 5-gallon increments, pulling the dipstick and marking the level with a file on the side of the dipstick at each stop.  Mirror or trace these marks on a piece of paper at the same time, noting the quantities.

C) Use a Sharpie to print the graduations on the dipstick.  If you use 10-gallon increments, consider using 5-gallon increments at the top.  Filling the tank without overfilling can be done easily if you know exactly how much fuel you need. 

Water tank:

A) Get a 5-gallon bucket like the kind that commercial liquids come in (ice cream, etc.).  Ensuring that others are not using the same water system, fill the bucket with a wide-open spigot and time how long it takes to get exactly 5-gallons.  

B) After confirming your time again so you are sure the timing is accurate, fill the empty tank and stop every ten gallons (by time).  Pull the dip stick and notch it.  Mirror the graduations by writing on a piece of paper. If you not getting too much turbulence in the tank, you can let the hose run and pull the dipstick strictly by time.

C) Use a Sharpie to print the graduations on the dipstick.  Let it dry before installing.  You can now figure out the total volume and use percent for graduations or just gallons.  You may be surprised that the fifty percent mark is almost three quarters of the way up the dipstick.

D) For an example using a water tank on a center cockpit Tayana V-42, see ftp://tognews.com/Tanks/Dipsticks  .

					Wayne Strausbaugh            V-42 RESTLESS