Reasonable setup for ultra long exposure for this kind of photo using Nikon D750

I’m using Nikon D750, and intend to take a ultra long exposure
picture such as this (by Michael Kenna).

enter image description here

What’s is the reasonable shutter speed and aperture for that?

If I use shutter speed 2 hr what is the right aperture for that?
f/22 is it still to high?