Every time this issue comes up, I find it incredible the lengths folk will go to to save a buck, with all this elaborate marking of the chain, when chain-counters are so damn cheap and pretty easy to install yourself, unless you got the real high end, self-parking types. Heck, if I can do it on my old dunger, anybody can...
They only cost a fraction of what you all fork out for sonar, Autopilot, GPS, Radar, AIS, etc, and yet it's the one thing you will use every time you drop anchor, and up-anchor, with no visibility issues whatsoever. You don't have to go out in the rain...ever...
I don't even have autopilot, AIS, or Radar, and manage fine without. But I'd hate to manage now without my chain counter. Had to once for a time, when the magnet rusted out - replaced with better one asap. Hated it the whole time until fixed. The last thing I want to have to do when manoeuvring to drop anchor is to try counting bits of coloured stuff flying over the end of the fricking roller..!
It's kinda like electric windows or remote locking on a car I guess. You never realise just how great it is until you have it.