For those that have boilers without graduations, what do you do to measure the volume of liquid in the vessel? If it's a measuring stick, what did you use?
I use a length of stainless steel that I marked every 3 litres.
The handle of a long wooden spoon/paddle, marked at 2 litre increments. I added 2 litres at a time and marked off each addition for the first 10 litres or so; each addition was 6mm apart so I did the remaining 50 litres with a ruler.
I use a ss ruler, measure down from the top and calculate volume in boiler from that (using the biabacus usually)