My brain hurts, so now I need help. I’m going to start programming/animating boat mechanics through third person possession, but I can’t get the boat to float ABOVE the sealine. I even used the “buoyancy” demo blueprint object, and the sucker floats under the waterline too. (I’m using the ocean water plugin… so maybe it’s not ready?).
The first pic is a top-down view. The second is from below. And the third shows the setup for the simulation. (All assets start ABOVE the water).
Hello Leomerya12, thank you for posting.
A few places/values I would check are:
Check if ‘Simulate Physics’ is checked on the boat mesh. If it is not checked, please do so.
Then check the Mass value. If its too heavy, it may not float as easily.
I was unable to see if your boat had a buoyancy component. Adding a buoyancy component and tinkering with the Pontoons value (adding members of the array/setting relative location) would also render results.
I hope this information assists you.
ppl seem to do better if they make sockets into the buoyancy points instead of using the collision box
Thank you for the response! Yes, the mass is low (100kg), though I’ve tested lower, and it flips under like a coin. And physics is enabled.
-The boat actually will go under the water, spring back up, out into the air, and then sink again once it’s landed.
Have you tried it on Unreal 5? I think the water is broken, because the buoyancy example (the cube) doesn’t float either. In UE4 it does.
Yes, I tried that, but again, it floats, but under the actual water line. I think it’s broken in UE5, because it works in UE4.
Have you tried it in 5 yet?
Thanks!
no
I haven’t tried it in 5
Haven’t been using water until I can test it with Quest VR.
examples I saw had the weight higher than you are using and 4 bouyancy points
Hello again, Leomerya12.
Yes, I was testing this all in UE5. I will happily share some screenshots. As mentioned by christuusgnosis, sockets are a great idea and will definitely give you a better sense of where your buoyancies are. I used four arrow components for on-the-spot-iteration.
Arrow Components/Pontoons:
I had to tinker with their locations but once I found a stable configuration and set them in the Pontoon’s relative locations, I found my yacht floated.
I noticed the floating was a bit volatile so I check marked ‘Apply Drag Forces in Water’ to true. This gave me a more stable boat experience. Here is my boat BP.
I hope this helps a bit.
Thank you for the visual! You are amazing. I will try this out and report my findings!
Hello Leomerya12, its great to hear back from you!
Looking at your screenshots, it looks like you will need to set the root as your boat mesh.
Your buoyancies look a bit high, can you lower them a bit?
As for the BP class, an Actor BP should suffice as this is what I have used. Looks like you’re using one as well. Great!
Edit to add: When placing your awesome boat into the water, please ensure the buoyancies aren’t in the water before pressing [Play] or [Simulate]. I noticed they sink if they are already in the water.
I look forward to your response.
Pardon the delay! I had some other Unreal fires to put out.
So, everything you said was spot on. What I noticed was that the WATER BODY INSTANCE was positioned too low (XYZ Arrow). So, the “buoyancy threshold” was below the waterline. This is actually a good mistake, because I can create some interesting effects in the future.
Thank you, so much, for your help!
Id like to revisit this thread in 5.4, because i have tried all of the following in this thread but the default buoyancy cube sinks to the very bottom of the floor. Any insight would be great, here also a list of everything i have tried to get you up to speed.
checking simulate button
enable mass (50kg)
setting the static mesh as root.
making sure both plugins are enabled (buoyancy and water plugin)
Things i noticed that are different:
i dont have a water body collisions channel
pressing simulate makes my water disappear
i cant enable the console debug command.
Anyway any tips or info would be super helpful 
Thanks!
Hello,
I haven’t touched the system since 2022, so while I’m much better at the Engine now, I have no recollection of how I/we got it to work.
If @Polite_Muon is still active, maybe they can help you.
I eventually figured out that you need a combination of water collisions tag in default ini and the object needs to be above the water when it starts. I missed the output log message that asks you to adds this normally.
The number one rule of programming:
READ EVERYTHING.
Yeah, I’ve been there.
