Greetings and welcome to the forum.
Depending on the rated resistance, the Nautilus coils are rated at: (1.6ohms 5v max, 1.8ohms 6vmax). I would not worry about TRYING to hit the maximum as you'll likely get burnt taste at anything over 3/4 the maximum rating.
Before I use a prebuilt atomizer/coil, I'll first check the airflow BEFORE I do anything by placing ether end in my mouth and blowing on it. Some factory coils can be a bit more clogged than others right out of the box.
Next I'll squirt juice down into the top until it is FILLED and leaking out the 510 connection end. Just set it on a paper towel for a 5-10min and inspect the 4 side holes, if they appear wet then your coil is primed and ready for installation - just put one end in your mouth and cover the other end with a paper towel and blow out the excess juice before installing.
While I have a handful of Nautilus tanks and used 50/50 to %100VG in them, I personally did not like using wattage mode with them and preferred using voltage mode. (given that the coils are rated in VOLTS and not watts) On the 1.8ohm coils I rarely could venture higher than 5V otherwise I'd be getting a burnt taste.
The atomizers/coils are fairly easy to rebuild. Instead of purchasing more prebuilts just to use my older tanks I rebuild them.
Volts are made of watts. In wattage mode you have fiber control that jumping in .1 or. 5 volt increments. A better example volts are the new radio on a chip where the frequency of the AM band jumps by 10. Wattage mode is the old transistor radio where you have the fine tuning wheel where you can narrowly tune in one station and tune out encroaching frequencies.
My Kayfun Nano is presently running a 1.2 Ohm coil at 12.5 watts, and the applied volts is 3.98.