Shorter steps:

  1. Steps 1-8 from Steps to reproduce (create level with water body)
  2. Find BP_BuoyancyExample in Content Browser (Engine>Plugins>Water Content>Blueprints)
  3. Place BP_BuoyancyExample above the water body surface (you can use z=500)
  4. PIE

Or you can see correspondent example in QAGameQA-Waterworks level -> Example 4A

More info:

  • No matter that weight is set to Cube component (check even 0.001 - Cube also falls on bottom of lake)
  • No matter how much Pontoons is added (in BP_BuoyancyExample there are four pontoons and it falls on bottom however in EA BP_BuoyancyExample buoyancies with only one pontoon (I removed all pontoons and create one new))
  • For now it's necessary to set Cube component as Default scene root (In other case cube will fall on the bottom of water body)
    Slack thread for this topic: [Link Removed]
  • Setting Cube Component mass to small values produce strange behavior: cube starts jumping on waves and can jump in air (very high - I don't know does it fall down after such jump or fly away)
    Slack thread: [Link Removed]


  • Can be reproduced on Windows
  • No info about other platforms

Regression: YES 

  • Can not be reproduced in 5.0.0 EarlyAcces 1 from Launcher
  • Can not be reproduced on the latest for this issue creating time EA CL: //UE5/Release-5.0-EarlyAccess - CL 16730400
Steps to Reproduce
  1. Create Blank BP project
  2. Enable Water plugin (Edit -> plugins -> search for Water plugin -> Click inside Enabled checkbox)
  3. Allow editor to restart
  4. Create new Empty level (File -> New Level -> Select Empty Level -> Select Don't save if you will be asked about saving changed assets)
  5. Switch to Landscape mode (Shift + 2)
  6. Tick Enable Edit Layers and press Create button
  7. Switch to Select Editing mode (Shift + 1)
  8. Add the following to the level (Search in Place Actors and drag to level):
  • Directional Light (place it anywhere)
  • Water Body Lake (place it anywhere)
  1. Create new Actor Blueprint (Right click in Content Drawer -> Select Blueprint Class -> Select Actor)
  2. Open created blueprint
  3. Add Cube component (click +ADD button in Components tab -> select Cube)
  4. Select Cube and update the following setting in Details Panel:
        Simulate Physics = true
  5. It's necessary step!
    Set Cube component as Root component (Click on Cube in Components tab and drag and drop it onto DefaultSceneRoot Component)
  6. Add Buoyancy component (click +ADD button in Components tab -> select Buoyancy)
  7. Select Buoyancy component
  8. In Details panel search for Pontoons  and add new element to Pontoons array (click + button near it)
  9. Compile blueprint
  10. Return to main Editor and place created blueprint on the lake surface (mean Water Body Lake created on step 8.)
  11. Move added to level blueprint instance upper (Select it and in Details panel set Location.z to 500)
  12. Play In Selected Viewport

Actual Result:

Cube (created blueprint with buoyancy) falls on bottom of the lake (see attached ActualResult.gif)

Expected Result:

Cube (created blueprint with buoyancy) falls on the water surface and starts to buoyance on it (see attached ExpectedResult.gif)


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ComponentUE - Simulation - Physics
Affects Versions5.0
Target Fix5.5
CreatedJul 26, 2021
ResolvedJun 27, 2022
UpdatedFeb 27, 2024