Keeping a spiral "true".
I am currently quilting a large spiral with my walking foot...it is about 42" in diameter at present and has another 12" or so to go. I have noticed that it is getting a little bit "out of true" obviously from my not being super accurate following the spiral with the walking foot. It's not very obvious but I was not wanting it to get any worse so is there a way to remedy this? If it was circles I could just measure the radius from the centre and draw where my next circle should be and follow that but as it is a spiral I'm not sure if it would work the same way? Any ideas or tricks? My friend says to just not worry about it, that when it is all finished any little wobblies won't be so obvious. Opinions please?