Keith Young Dulcimer
Instruments- discuss specific features, luthiers, instrument problems & questions
Keith's bridges have a SLOT into which they fit nicely. This is confirmed in the photos. In one respect, if they are not glued, they can be called 'floating' since they can be removed once all strings are off.
However, talk about moving or determining the location of a 'floating' bridge is just not applicable here. Keith located the deep bridge slot exactly where it needs to be to be in tune with the fret placements, and the bridge drops into that slot. No need to figure out where to put the bridge.
Keith typically provided bridge and nut string slots that could be used to accommodate various ways of stringing, such as: Four equidistant strings. Three strings with a bass, a middle, and a single melody string. And 4 strings using bass, middle and a pair of melody strings. You can see this string slot choices setup provided by Keith in your photos.
BTW If you choose to play with a noter and a single melody string, I recommend using the melody string slot closest to the edge of the fingerboard, which would give just a bit of extra space between the melody string and the middle string- this helps in avoding bumping into the middle string with one's noter.
Your Young teardrop is very much like mine (you can see mine in the logo at the top of this site). You've got yourself a real beauty, a treasure! It will become more valuable with time if you don't make structural changes to it. Enjoy that wonderful dulcimer!
updated by @strumelia: 10/30/18 11:40:08AM