It missed fairly large fishing boats in Maine pretty regularly. We motored back from down east to Bar Harbor in thick fog, around 200 ft visibility. Probably saw 15 lobster boats, less than half showed up on radar before seeing them, if then. Even some fairly large (130') steel fishing boats didn't show up in a bit of seaway off Nova Scotia. That is the reason for upgrading the radome, don't know if it will do a lot of good but one might as well try - they aren't actually very expensive these days.

I have gotten a lot more use out of the radar for navigation than collision avoidance. It picks up buoys pretty well, overlaid on the chart plotter you can navigate with some confidence in zero/zero. As long as you don't hit an invisible panga or lobster boat!