Originally posted by Yasik:

Is there any other way to protect the boat?

They are both prevented from spawning by workbench radius, and attracted to workbenches to destroy them. You can use this against them by elevating the workbench and surrounding it with ground spikes and collect the wood and grey eyes. Before I was good enough to build docks I always used the large natural boulders as docking points for portals and such. Once I could build stone I sealed workbenches inside large stone blocks underwater for similar effects with underwater spikes. Keeping the boat in the water a bit away from shore with a big rock between seems to help screw their pathing too as they don't really like moving over the uneven boulder surface, and big rocks are convenient to build portals and chests on for boat collecting ore.

I never had a real problem with events at my main dock except dragons flying in to eat all my boars but I also kept a wood stake fence surrounding my base which went mostly to the shoreline, then dug a deep troll depth ditch around that then grew a treeline around that except for a strip at the beach for ease of access and a set of wood spikes there which was moderately effective and usually destroyed. I'm also a very active defender so I'd just go out and kill everything away from the base anyway. I thought of keeping bees in my treeline for additional defensive fun but bees are rare enough to where I didn't want them screwed with. Wolf pens at the corners might have been fun but I deemed it too much effort for little effective reward. I kind of wish this game had more tower defense aspect sometimes like 7D2D does. My plains outpost is a built up fortress between two stone monoliths and survives constant tar pit slimes (which wreck structure faster than troll, but it's in my backyard as a great resource) and goblin berserkers raids, mainly by being higher up than their AI can deal with so I go out and fight them at leisure.