Do you use an immersion chiller? The reason I ask is I'm trying to improve the logistics of my brewing at flameout thru chilling and hop additions and creating a whirlpool. My IC goes in the kettle with about 10-15 min left in the boil. At flameout I don't immediately start the chiller but just let the temp fall to 180 then toss in some hops. After 10-20 minutes I start chilling. I don't remove the chiller until I'm in the high 60's. Remove chiller then whirlpool for 5 minutes in an attempt to settle the trub although I'm in the Brulosophy camp of not sweating some trub in fermenter.
Can hops be added when the wort is chilled to mid 60's? That is when I start a whirlpool.
I would not add hops with temps at mid-60's. The temperature and duration are infinitely more important than an actual whirlpool. People use the term WP differently with respect to temp, but I diferentiate between FO additions at WP additions. I frequently add hops at both points. Add at FO, wait 5 mins then turn on the chiller until I hit 170, stop the water to the chiller and add WP hops. I let those steep for 20-30 minutes, then resume chilling to pitching temps (mid-60's). I have my pump running to whirlpool the whole time, but I only consider the 170 degee addition as a WP addition...again, for me it's a temp thing, not the fact that the pump is running. For that matter, I have the pump running from 15 mins to zero, but that doesn't make my 5 minute addition a WP addition either.
The reason I say don't add with temps at the 60's is two fold. First, it's not really different than a dry hop except for (second) - unfermented wort is high risk for infection. Dumping in hops into fermented beer has alchohol that reduces risk of infection. Pre-fermentation, you're taking a risk for little benefit.
In general consider hop addition effects as a spectrum from pretty much all bittering at 60 minute boil to mostly aroma for a dry hop. In between is transitions to less bittering and more flavor, then more flavor and aroma, then on to mostly aroma.
So late boil and FO are what I consider my flavor additions...they add some bittering, but not much and add a lot of flavor. WP additions are flavor and aroma with almost no bittering in the traditional sense (isomerization).
Decide on your bitter/flavor/aroma profile and add hops to reach that. For example, my first IPAs were just 60 min and DH additions. I wanted more flavor but the same IBU, so I cut the 60 minute out completely and and used sizeable additions at 5 mins, FO and WP along with the DH. Since the utilization is so much less at 5 mins and FO, I coulld add more, get more flavor since they were boiled less, and still be at the same IBU level. Worked like a charm.