diff --git a/buoy_interfaces/CMakeLists.txt b/buoy_interfaces/CMakeLists.txt
index efa0be2..9c3dd69 100644
--- a/buoy_interfaces/CMakeLists.txt
+++ b/buoy_interfaces/CMakeLists.txt
@@ -13,7 +13,9 @@ find_package(sensor_msgs REQUIRED)
 find_package(std_msgs REQUIRED)
 
 rosidl_generate_interfaces(${PROJECT_NAME}
+  "msg/AirSpring.msg"
   "msg/BCRecord.msg"
+  "msg/ElectroHydraulic.msg"
   "msg/IncWaveHeight.msg"
   "msg/LatentData.msg"
   "msg/PBCommandResponse.msg"
@@ -22,6 +24,7 @@ rosidl_generate_interfaces(${PROJECT_NAME}
   "msg/PCRecord.msg"
   "msg/SCRecord.msg"
   "msg/TFRecord.msg"
+  "msg/WaveBodyInteractions.msg"
   "msg/XBRecord.msg"
   "srv/BCResetCommand.srv"
   "srv/BenderCommand.srv"
diff --git a/buoy_interfaces/msg/AirSpring.msg b/buoy_interfaces/msg/AirSpring.msg
new file mode 100644
index 0000000..d9ef217
--- /dev/null
+++ b/buoy_interfaces/msg/AirSpring.msg
@@ -0,0 +1,6 @@
+float64 force  # Newtons
+float64 temperature  # K
+float64 heat_loss  # dQ/dt in Watts
+float64 piston_position  # meters
+float64 piston_velocity  # m/s
+float64 mass  # kg
diff --git a/buoy_interfaces/msg/ElectroHydraulic.msg b/buoy_interfaces/msg/ElectroHydraulic.msg
new file mode 100644
index 0000000..89c581b
--- /dev/null
+++ b/buoy_interfaces/msg/ElectroHydraulic.msg
@@ -0,0 +1,17 @@
+float64 rpm
+float64 upper_hydraulic_pressure  # Pa 
+float64 lower_hydraulic_pressure  # Pa 
+float64 force  # Newtons
+
+float64 supplied_hydraulic_power  # Watts
+
+float64 hydraulic_motor_loss
+float64 relief_valve_loss
+float64 shaft_mech_power  # Watts
+
+float64 motor_drive_i2r_loss
+float64 motor_drive_switching_loss
+float64 motor_drive_friction_loss
+float64 load_dump_power
+float64 battery_i2r_loss
+float64 battery_storage_power
diff --git a/buoy_interfaces/msg/LatentData.msg b/buoy_interfaces/msg/LatentData.msg
index 0512f65..bea0a85 100644
--- a/buoy_interfaces/msg/LatentData.msg
+++ b/buoy_interfaces/msg/LatentData.msg
@@ -2,4 +2,13 @@ std_msgs/Header header
 
 IncWaveHeight[] inc_wave_heights
 
+AirSpring upper_spring
+AirSpring lower_spring
+
+ElectroHydraulic electro_hydraulic
+
+WaveBodyInteractions wave_body
+
+float64 piston_friction_force  # Newtons
+
 # TODO(andermi) fill in other stuff
diff --git a/buoy_interfaces/msg/WaveBodyInteractions.msg b/buoy_interfaces/msg/WaveBodyInteractions.msg
new file mode 100644
index 0000000..178afaf
--- /dev/null
+++ b/buoy_interfaces/msg/WaveBodyInteractions.msg
@@ -0,0 +1,14 @@
+
+# Motion
+geometry_msgs/Pose pose  # position/orientation
+geometry_msgs/Twist twist  # linear/angular rates
+
+# Forces/Torques
+geometry_msgs/Wrench buoyancy
+geometry_msgs/Wrench radiation
+geometry_msgs/Wrench excitation
+
+# Total power = dot(force, velocity) + dot(torque, omega)
+float64 buoyancy_total_power  # Watts
+float64 radiation_total_power  # Watts
+float64 excitation_total_power  # Watts