Nuclear submarine docking - if then

I am trying to write a massive if>then statement dealing with sub docking numbers (0-0-0+) (ft-in-8ths).

The if.then statement will not include any addition or subtraction just basically if you input 1/16 it will place 0-0-2....... But there is 48 if then's........ The decimal number you input does not relate to the docking number outputed in anyway other than the fact they are on a chart. Can someone point me in the right direction or atleast point me to a thread that would help me?

The excel sheet i attached is not the one i am needing the if then for. Its just the chart i am making it off of.