One of those niche, (presumably?) widely-unknown bugs that is actually extremely relevant to subcommunities of people who play the game - in particular, any decent Minecraft speedrunner is well aware of "boat break" and plays around the possibility.
Part of the reason I love speedrunning games in general is how it tends to bring weird bugs to the forefront of your consciousness, just like this!
I tried to play SubNautica for a bit (after playing some Minecraft) but they put their waiting loop in "the wrong place" ... in Minecraft you have to wait to "retrieve the items" (ie: mine 100 stone blocks), while in Subnautica you had to wait to "combine the items", ie: staring at a boring progress bar while trying to craft some rubber suit fins or whatever. It seemed like it was going to turn into a "stare at the progress bar to build things" game and that really turned me off from sticking with it.
Because the page lazy-loads comments that link doesn't work either.
Full text of the comment from migrated 9/11/2020, 1:38:27 PM:
I saw the same Reddit post and decided to investigate. I skimmed MCP 1.12 because I still have it lying around and that version is affected.
In what it calls EntityBoat’s updateFallState, if the boat’s status is not ON_LAND, fall damage is nullified. That will be the case when falling from most heights, because the last time the boat’s status was updated was before it hit the ground. There is only a small exception because the boat checks blocks up to a thousandth of a block below it when updating its status. If it ends up just barely above the ground, its status becomes ON_LAND before hitting the ground, allowing fall damage to take effect.
This happens at the given heights because gravity subtracts 0.04F from the boat’s Y velocity. If it were exactly 0.04, the boat would have fallen an integral number of blocks every 2 ticks out of 25: 12, 13; 49, 51; 111, 114; 198, 202; and so on. The boat ends up falling very slightly less than that because 0.04F is rounded down as a 32-bit float, placing it just above the ground and allowing it to become ON_LAND before hitting it.
Part of the reason I love speedrunning games in general is how it tends to bring weird bugs to the forefront of your consciousness, just like this!
Full text of the comment from migrated 9/11/2020, 1:38:27 PM:
I saw the same Reddit post and decided to investigate. I skimmed MCP 1.12 because I still have it lying around and that version is affected.
In what it calls EntityBoat’s updateFallState, if the boat’s status is not ON_LAND, fall damage is nullified. That will be the case when falling from most heights, because the last time the boat’s status was updated was before it hit the ground. There is only a small exception because the boat checks blocks up to a thousandth of a block below it when updating its status. If it ends up just barely above the ground, its status becomes ON_LAND before hitting the ground, allowing fall damage to take effect.
This happens at the given heights because gravity subtracts 0.04F from the boat’s Y velocity. If it were exactly 0.04, the boat would have fallen an integral number of blocks every 2 ticks out of 25: 12, 13; 49, 51; 111, 114; 198, 202; and so on. The boat ends up falling very slightly less than that because 0.04F is rounded down as a 32-bit float, placing it just above the ground and allowing it to become ON_LAND before hitting it.