I used a tripod -- I love my Manfrotto -- perched right on the walkway alongside the water. The nifty fifty is great for sharp, long-exposure shots. I'd think the critical factor here was not merely the ISO, but the smaller aperture that I used.
And no, I couldn't see the boats in person; I could see the masts outlined against the lights, but it was far too dark to see the boats.
(As for the apartments, I took a 300mm shot later, and was startled to realize you can see the pictures on the walls through windows, in that one.)
Glad folks like it!