undock and dock

[*Wiro]

When undocking, you can insta-dock to:
Harbours
Ships that were already there before you undocked

You can never insta-dock to land. It has nothing to do with ship speed. It's unclear if this was done on purpose to prevent abuse (instantly docking without warning is an issue, you could easily sail around the harbour lock) or if it's just a bug. So you have to move a bit and then dock.

Ships that undocked after you did won't be dockable until you move a bit.

[sanchez]

It’s important to distinguish between re-docking, and docking from sailing on open sea. When you undock from a ship, that ship is not including in your (re)docking target list until the list is refreshed at the next sailing tick. If there’s another ship floating, you should be able to dock to the second ship, undock, and then you’ll see your original ship in the new docking target list. Same should apply to ports, though that is potentially exploitable.

It’s supposed to still be possible, in theory, to instantly dock to land. Only finding the right location and the correct ship speed and position seems nearly impossible. I don’t recall this always being so difficult, but then again, I don’t have a lot of chars sailing along undeveloped coastlines in smaller boats now, so opportunities for testing are limited. The new incremental docking system takes into account when your ship is sailing on land, and though this should not affect the docking process (other than the arbitrary restriction of not allowing you to either cancel docking or undock a smaller vessel while moving over land) maybe some land-based targets are seen as farther inland now, so only faster boats such as rigged sloops can manage it? What has changed, -I think-, is to make it a little less tricky to dock to a moving ship in open sea, something which required more precise triangulation in the past, but which can now be compensated for by relative ship speed, and is not automatically cancelled if not instantly successful. It would be nice to hear some more recent anecdotal evidence from in game.

[Kyriel]

Yeah, the problem with the "moving a bit" requirement is that if you're already too close to land, you will hit the shore if you try to move any closer and still not be able to dock anywhere. And unless you already know about this particular bug, you will have no idea why. I spent several hours stuck out at sea once trying to dock and trying to figure out why it wasn't working.