Information straight from the Ky Boaters guide regarding locks.
______________________________________________
Dams associated with the locks
can be very dangerous. Below all locks
and dams, boat occupants must wear a
personal floatation device (lifejacket)
upstream of danger signs and open-diamond buoys or within 150 feet of the
downstream lock and dam wall.
__________________________________________________ _________
So it isn't in the locks where vests are required. It is below regardless if you are locking through or not.

Information regarding accessibility:
__________________________________________________ __
Accessibility: PFDs must be readily
available for immediate use by all
occupants of a vessel. It is advisable
for each person to try on their PFD
before departing so that they are familiar with the fastening devices and
to assure it is adjusted to the person.
PFDs shouldn’t be stored in the
plastic bags in which they were sold.
This limits access and can promote
rotting.
__________________________________________________ ________


This does not say they have to be on the deck. I've been through coast guard checks where they fully expected me to pull them from an available hatch but they were actually hanging in plain sight and they didn't expect it.

__________________________________________________
Usage:
(301 KAR 6:020 Sect. 4); KRS 235.203
For each person onboard a vessel,
federal as well as state law requires a
Type I, II, or III personal flotation device (PFD) on all boats. Boats 16 feet
and over, except canoes and kayaks, must
also carry one Type IV throwable PFD.
Operators and passengers of personal
watercraft must wear a PFD. Persons
under 12 years of age must wear a PFD
while in the open part of a boat that is
under way.
__________________________________________________ ______


Oddly, they do not cover inflatables. But it's my understanding those only count when worn. You could have a standard device stored, not wear your inflatable, and still be legal.


Here are the regulations for those interested.
https://fw.ky.gov/Fish/Documents/18-...hing_guide.pdf