The bug
A boat will glitch / sink through blocks when it falls onto shallow water (see screenshot for setup to reproduce glitch or 3 Glitches with Boats- 1.12 Vanilla Survival)
How to reproduce
Grab a boat
Create setup shown in screenshot
Speed up using 'W' and move towards the waterfall. once you fall on the floor below, you will sink/glitch through the ground, as shown in the video here: https://www.youtube.com/watch?v=Q8mtxsNCOAE
Code analysis
Based on 1.12.2 decompiled using MCP 9.40
It appears the call to Entity.setPosition(double, double, double)
in the method net.minecraft.entity.item.EntityBoat.updateMotion()
is causing this:
if (this.previousStatus == EntityBoat.Status.IN_AIR && this.status != EntityBoat.Status.IN_AIR && this.status != EntityBoat.Status.ON_LAND)
{
this.waterLevel = this.getEntityBoundingBox().minY + (double)this.height;
// The following line appears to be causing the bug
this.setPosition(this.posX, (double)(this.getWaterLevelAbove() - this.height) + 0.101D, this.posZ);
this.motionY = 0.0D;
this.lastYd = 0.0D;
this.status = EntityBoat.Status.IN_WATER;
}
It is unknown if leaving this out solves this bug without causing any other problems.
Linked issues
is duplicated by 32
Attachments
Comments 22

Tell me what the issue was for reproducing it @FVbico
Were you in the latest snapshot.
Try going at full speed and use F5 mode for optimal setup. (Reference the video if needed)
I was and I was, it just didn't happen to me
I was able to reproduce it. (16w04a)
1. Launch the boat off the upper level of water.
2. Keep holding “W” until landing in the lower flowing water.
Was able to reproduce in this video: https://www.youtube.com/watch?v=4FNCWE3xgL4
Can confirm in 22w42a. This now also affects bamboo rafts.
Can confirm in 1.19.2.

Can confirm in 1.20.1 per MC-263572.

Can confirm in 1.20.4.
can't believe this bug is 8 years old
cannot confirm