Extended fretboards revisited

I was asking about preferences in"uke talk" about extended fretboards.
I look at Martin Style 3 and five and wonder about the extended fret board.
Doesnt it stop the soundboard from moving? Alot of acoustic guitars with long fretboards have a space between the fretboard and the top. I assume this is so the top can "move". With such a small soundboard doesnt the 17 fret extended fretboard stop the top from working the way it should? Am I wrong in thinking that the top has to "vibrate" for optimum sound? Is this more a guitar thing than ukulele? Thanks.

I'm thinking that the size difference does indeed make it more of a guitar deal than uke. That could also explain the use of soundboard woods you almost never see on guitars. With few exceptions, guitars use spruce or cedar. Ukes use just about anything, usually matching the back and sides which is also nearly never done on guitars.

My theory is that while guitars rely more on top vibrations combined with box resonances, ukes rely more heavily on the soundbox and less on the top. That's why ukes will never really sound like a guitar. Similar shape, similar construction, different instruments.

The extended fretboard, even on guitars, usually sit on top of a supporting block inside the soundbox, so it really doesn't impact anything one way or another. I know only of a few (flat top, not archtop) guitars that have a cantilevered fretboard that floats over the soundboard.

Rick Turner builds the Compass Rose this way. I won't presume to speak for him but two of the reasons he has mentioned here are 1) to allow the upper portion of the top to vibrate and 2) to make it unnecessary to perfectly match the angle of the fretboard to the top.

Do you hear much difference between a short fingerboard and an extended one? I haven't done the test myself....wonder if anyone has. I'm not aware of anyone making the same model with short or extended fingerboards as the only difference.
I do the extended fingerboard only.....I need it to cover the sloppy end of my rosettes

You can sit around, bandying theories all day or you can just do the experiment. Take some ukes with short fretboards, make up a little dummy extension, get a couple of magnets to hold it in place and then do some blind tests. In the case of floating fretboards, slide a chock in to couple the fretboard to the top and then blind test.

Personally, my uke design has heavy structure in the upper bout to strengthen the neck joint. The soundboard's "diaphram" is below the soundhole. I do short fretboards because they look traditional and because I've seen three people in my life do anything meaningful above the 12th fret. They can have a long fretboard is they ask nicely. Not on a soprano though, nobody has fingers that small.

If Rick says that he can hear a difference on his instruments with a floating fingerboard as opposed to not, then I'm dead certain on his instruments that's the case.

On mine, I could not honestly say I hear a difference. The sopranos get a short one because it looks better. The tenors get a long one because everyone want's all the frets they can get. On concerts I flip between one or the other for no particular reason other than what I think looks good on that day.