Why don't you just make it easy and mark your chain in 30ft or 30 meter increments then let it out corresponding to fathoms x one or meters divide by two in relation to actual depth
. Adding an extra 8ft at the beginning to account for freeboard + snubber slack?
Example, if the chart says you are in 2 fathoms... Let out the chain to the second mark. Or if the chart says 4 meters... Let it out to the second mark for five to one scope
. Double the amount for 10:1. What could be easier?
We have our chain marked in yellow, red, green and blue. Just let it out to each mark corresponding to depth
for 5:1 or double it to the next series of yellow, red... Marks for 10:1. No calculators or math problems involved.