As GattoNero indicated, it definitely needs a permit. When our (not)permanent dock,

, was destroyed by ice a few years back, we replaced it with a crank-up. Watermark handled the permitting and installation. We have 100' frontage and Watermark stated that would allow a 6 X 40 dock, 1 seasonal boatlift, and 1 seasonal jetski lift, (amount of frontage dictates what you can have). I have no intention of ever using a boatlift or owning a jetski, but the thought was better to go to the well once and get everything approved that could be allowed, even if we never use it.
Since there are 4 homeowners who own the waterfront, my guess is that all 4 of you, (or your association, if you have one), will need to be on the application, but definitely check with the state on that one.
Good luck.