diff --git a/ArduSub/config.h b/ArduSub/config.h
index db5c2f954f32f1..d2ee20d65120d6 100644
--- a/ArduSub/config.h
+++ b/ArduSub/config.h
@@ -183,6 +183,10 @@
 # define AUTO_DISARMING_DELAY  0
 #endif
 
+#ifndef NEUTRAL_THROTTLE
+# define NEUTRAL_THROTTLE (0.5f)   // Throttle output for "no vertical thrust"
+#endif
+
 //////////////////////////////////////////////////////////////////////////////
 // Logging control
 //
diff --git a/ArduSub/mode_acro.cpp b/ArduSub/mode_acro.cpp
index 29b1e61891667c..8df7ddb44c4872 100644
--- a/ArduSub/mode_acro.cpp
+++ b/ArduSub/mode_acro.cpp
@@ -23,7 +23,7 @@ void ModeAcro::run()
     // if not armed set throttle to zero and exit immediately
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         return;
     }
diff --git a/ArduSub/mode_althold.cpp b/ArduSub/mode_althold.cpp
index cf5b2a952f508c..f1742d4b845406 100644
--- a/ArduSub/mode_althold.cpp
+++ b/ArduSub/mode_althold.cpp
@@ -38,7 +38,7 @@ void ModeAlthold::run_pre()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when not auto-armed (i.e. on the ground, pilot has never raised throttle)
-        attitude_control->set_throttle_out(0.5,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         position_control->relax_z_controller(motors.get_throttle_hover());
         sub.last_pilot_heading = ahrs.yaw_sensor;
diff --git a/ArduSub/mode_auto.cpp b/ArduSub/mode_auto.cpp
index 57e086118982e4..8792db4bf86de2 100644
--- a/ArduSub/mode_auto.cpp
+++ b/ArduSub/mode_auto.cpp
@@ -111,7 +111,7 @@ void ModeAuto::auto_wp_run()
         // call attitude controller
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         sub.wp_nav.wp_and_spline_init();                                                // Reset xy target
         return;
@@ -302,7 +302,7 @@ void ModeAuto::auto_loiter_run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
 
         sub.wp_nav.wp_and_spline_init();                                                // Reset xy target
@@ -475,7 +475,7 @@ void ModeAuto::auto_terrain_recover_run()
     // if not armed set throttle to zero and exit immediately
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
 
         sub.loiter_nav.init_target();                                                   // Reset xy target
diff --git a/ArduSub/mode_circle.cpp b/ArduSub/mode_circle.cpp
index 28be79dbad54cd..3af9b2a67abcb2 100644
--- a/ArduSub/mode_circle.cpp
+++ b/ArduSub/mode_circle.cpp
@@ -41,7 +41,7 @@ void ModeCircle::run()
         // To-Do: add some initialisation of position controllers
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         sub.circle_nav.init();
         return;
diff --git a/ArduSub/mode_guided.cpp b/ArduSub/mode_guided.cpp
index ff1bb07df5681a..199a392162f459 100644
--- a/ArduSub/mode_guided.cpp
+++ b/ArduSub/mode_guided.cpp
@@ -457,7 +457,7 @@ void ModeGuided::guided_pos_control_run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         sub.wp_nav.wp_and_spline_init();
         return;
@@ -522,7 +522,7 @@ void ModeGuided::guided_vel_control_run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         // initialise velocity controller
         position_control->init_z_controller();
@@ -595,7 +595,7 @@ void ModeGuided::guided_posvel_control_run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         // initialise velocity controller
         position_control->init_z_controller();
@@ -675,7 +675,7 @@ void ModeGuided::guided_angle_control_run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when disarmed
-        attitude_control->set_throttle_out(0.0f,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         // initialise velocity controller
         position_control->init_z_controller();
diff --git a/ArduSub/mode_manual.cpp b/ArduSub/mode_manual.cpp
index 9d6e29892ea91a..5b9da67eeea0e5 100644
--- a/ArduSub/mode_manual.cpp
+++ b/ArduSub/mode_manual.cpp
@@ -19,7 +19,7 @@ void ModeManual::run()
     // if not armed set throttle to zero and exit immediately
     if (!sub.motors.armed()) {
         sub.motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         return;
     }
diff --git a/ArduSub/mode_poshold.cpp b/ArduSub/mode_poshold.cpp
index a5cb3d9bfd050d..d9037abb7105e2 100644
--- a/ArduSub/mode_poshold.cpp
+++ b/ArduSub/mode_poshold.cpp
@@ -25,7 +25,7 @@ bool ModePoshold::init(bool ignore_checks)
     position_control->init_z_controller();
 
     // Stop all thrusters
-    attitude_control->set_throttle_out(0.5f ,true, g.throttle_filt);
+    attitude_control->set_throttle_out(NEUTRAL_THROTTLE ,true, g.throttle_filt);
     attitude_control->relax_attitude_controllers();
     position_control->relax_z_controller(0.5f);
 
@@ -43,7 +43,7 @@ void ModePoshold::run()
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
         // Sub vehicles do not stabilize roll/pitch/yaw when not auto-armed (i.e. on the ground, pilot has never raised throttle)
-        attitude_control->set_throttle_out(0.5f ,true, g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE ,true, g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         position_control->init_xy_controller_stopping_point();
         position_control->relax_z_controller(0.5f);
diff --git a/ArduSub/mode_stabilize.cpp b/ArduSub/mode_stabilize.cpp
index 52620b8d5d0b6a..fd11d4d9011f72 100644
--- a/ArduSub/mode_stabilize.cpp
+++ b/ArduSub/mode_stabilize.cpp
@@ -18,7 +18,7 @@ void ModeStabilize::run()
     // if not armed set throttle to zero and exit immediately
     if (!motors.armed()) {
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         sub.last_pilot_heading = ahrs.yaw_sensor;
         return;
diff --git a/ArduSub/mode_surface.cpp b/ArduSub/mode_surface.cpp
index 6bab07a067b860..cb56b4783b06f1 100644
--- a/ArduSub/mode_surface.cpp
+++ b/ArduSub/mode_surface.cpp
@@ -26,7 +26,7 @@ void ModeSurface::run()
     if (!motors.armed()) {
         motors.output_min();
         motors.set_desired_spool_state(AP_Motors::DesiredSpoolState::GROUND_IDLE);
-        attitude_control->set_throttle_out(0,true,g.throttle_filt);
+        attitude_control->set_throttle_out(NEUTRAL_THROTTLE,true,g.throttle_filt);
         attitude_control->relax_attitude_controllers();
         position_control->init_z_controller();
         return;