HydroSim is a standalone Hydroplane racing simulator built with the Unity3D game engine. It currently simulates Unlimited Hydroplanes from the H1 Unlimited racing series.


Get HydroSim Current Version

Extract the zip file to C:\HydroSim and run HydroSim.exe


Get HydroSim Current Version

Extract the zip file to ~/HydroSim and run ./HydroSim


Get HydroSim Current Version

Extract the zip file and run HydroSim.app
Note: Mac OSX build is experimental and may have rendering issues. Boat wakes are currently not supported.

Info and Keybindings

Control Mappings:

When you first launch the game, there is a dialog box, click the Input tab. From here you can map the following controls:

  • Throttle
  • Rudder
  • Canard
  • LookLeft
  • LookRight

Key Bindings

Camera controls:

  • Insert/Del: Cycle onboard cameras
  • PageUp/PageDown: Cycle TV camera groups
  • End: Enable mouse control on stationary TV cameras.
  • Home: Cycle stationary TV cameras.
  • [: Zoom out stationary camera.
  • ]: Zoom in stationary camera.
  • Numpad+/-: Cycle other drivers


  • Left Arrow: Rewind
  • Right Arrow: Fast forward


  • R: Reset the boat (if you flip over)
  • T: Chat
  • Esc: Exit the boat
  • Ctrl+F: Show FPS/Ping

Join UHL server

Replace localhost with www.uhlhydroplanes.com and click Join

Run in VR Mode

Goto Settings->Display and set VR Mode to Oculus or OpenVR.
Recenter the view with F4 key (Can be bound to a different key in the Input binding dialog when launching the game).

Run as borderless window

Create a shortcut to HydroSim.exe and add the following command line options to Target

"C:\HydroSim\HydroSim.exe"  -popupwindow -screen-width 1920 -screen-height 1080

Run as Dedicated Server

Create a shortcut to HydroSim.exe and add the following command line options to Target

"C:\HydroSim\HydroSim.exe" -nolog -dedicated -batchmode -nographics -serverIP -admin hydroadmin -maxPlayers 12 -tickRate 30

You can also add a password by adding the -password <serverPassword> flag.

The server is currently hardcoded to use port 25144 on both TCP and UDP. If you want other people to be able to connect to the server on the open internet, you will need to open the port on your firewall. If you're behind a router, which is likely, you'll need to login to the router and forward the port to your computer running the server.

Custom Paintjobs

Custom Teams / Paintjobs can be added to the game by adding a new folder to the StreamingAssets/Teams folder. There are lots of Teams (as well as Photoshop templates for making custom teams) available on this Google Drive: https://drive.google.com/drive/folders/1DIOr89tJfDemsREYHmlu6wHNi_Ua7C4M?usp=sharing

Within a team folder you can add the following DDS textures.

Hull.dds - The main hull texture.
Cowling.dds - The engine cowling texture.
Cockpit.dds - The cockpit texture.
SaltWaterScoop.dds - The salt water scoop (for turbine hulls).
Hardware.dds - Various other parts of the hydroplane.
Engine.dds - The engine texture (for piston hulls).
Trailer.dds - The texture for the boat trailer that gets placed in the pits.

Each of the above textures can also have an _met.dds which is the Metallic map. The red color channel determines metallicness and the Alpha channel determines smoothness.

As of HydroSim v0.7.0.0, Crunch compressed DDS files can also be used. This can greatly reduce the file size of the custom paintjob textures. In order to compress the files the following Crunch command line application needs to be used:




Scott Przybylski - Physics / UI / Netcode / Race logic / Replays / etc

3D Models

Scott Przybylski - Boats / Race Course Scenery
Kallen Washburn - GP Hydroplanes
Tim Johnson - Blue Bridge


Scott Przybylski - Scenery
Matt Johnson - UI Graphics / Logos / Boat paints
Craig Montgomery - Boat paints
Chris Porten - Boat paints / templates


Eddie Kanfoush - Prop noise
Gavin McClure - GP engine sounds

Special Thanks

Todd Wasson - Physics help
Brad Warren - Physics help

Everyone else I missed who has helped with testing, reporting bugs,
gathering info, pictures and data.

Unity Assets

Crest Ocean SDK - https://github.com/crest-ocean/crest
Dynamic Water Physics 2 - Hull / Buoy water physics
Time of Day - Sky and Lighting
TerraLand - Real World terrain
MicroSplat - Terrain shaders
Vegetation Studio - Trees / foliage
NatureManufacture - Trees
MTree - Trees
EasyRoads3D - Roads / bridges
BuildR3 - Buildings