THE THING TO NOTICE
In BerthLab, neutral changes the propulsion target. It does not set velocity or rotation to zero. Review the frames after neutral to understand the difference between a command and the model’s response.
Begin with one controlled comparison
Choose the original training boat and the Inertia exercise. Keep the scene calm and use the same starting conditions for your comparisons. Watch the motion after you select neutral instead of judging the attempt only by its final position. This separates one input decision from changes in vessel configuration or environment.
Look at two different moments
In replay, find the neutral event on the timeline. Observe the boat immediately before it and then a few seconds afterward. The input target has changed, but the vessel still carries recorded velocity and actual actuator state. A trajectory overlay helps show how far it continues to travel. The replay displays stored samples rather than rerunning a newer physics model.
Try a more deliberate second attempt
Use takeover from a recorded moment before the final approach. The new fragment preserves motion and actual actuator state while neutralizing the new thrust target; it does not freeze the boat in place. Change when you reduce propulsion, then compare the paths. A fragment is a separate practice attempt and does not count as completing an authored lesson.
What not to take away
The model’s stopping distance is not a recommendation for a real boat. Loading, drivetrain, hull, weather and surroundings may all differ. BerthLab is a place to observe a conceptual response, not to discover a universal safe speed or braking distance.
Source and limits
This note describes BerthLab’s versioned simulator and recorded-replay behavior, reviewed against the Pilot Edition source. It is not an independently validated on-water training method.
Read the model and editorial methodology · Explore the related exercises