Put the summary of the bug you're having here
What I expected to happen was...: The boat to go off the block
What actually happened was...: The boat breaks like how it used to be before it dropped itself.
Steps to Reproduce:
1. Place a boat on a L shaped surface with 2 path blocks and 1 grass block.
2. Get in the boat.
3. Hold W and sprint while rowing toward the empty space that, if you place a block down to create a full 2x2x1 space, and you should sink through the boat, take damage, and the boat breaks into 3 wooden planks and 2 sticks.
Related issues
Comments

Resolve forward to MC-201158 as it has a clearer description. Thanks for your report!
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The instructions are vague. What does the L look like? I tried a few interpretations and can't reproduce this in 1.16.2.