i'm leveling up a BO for Montana on a CV, it has potintial +14, just change the nation,
I found the equation for calculating the guideline length in " Adalbert's Sailor Ability Guide", which is

"
A higher value on potential for the BO lets your guidelines grow and mark shells further.
The marking range of the FCS is the only other variable that matters for guideline length.
Your guideline length in tickmarks is :

--> 11.1 * (true BO potential / 1000000) + 12.6 * marking range [km] <--
"

I remember if I level up the BO by this method, it will lose some ability, but not sure how much.
Can someone tell my how much ability it will lose? by percentage.
so I can know when should I class it to BO, so it will have guideline long enough.
Thanks.