Which statement best defines open-loop versus closed-loop speed control in a marine engine's governing system?

Which statement best defines open-loop versus closed-loop speed control in a marine engine's governing system?

• A. Open-loop uses preset fuel without feedback.
• B. Closed-loop uses speed or frequency feedback to adjust fuel and maintain set rpm.
• C. Open-loop uses preset fuel without feedback; closed-loop uses speed or frequency feedback to adjust fuel and maintain set rpm.
• D. Closed-loop uses only manual throttle adjustments.

Answer: (C)

Understanding how open-loop and closed-loop speed control differ in a marine engine governor is key. Open-loop control sets the fuel input on a preset schedule with no measurement of the actual engine speed—there's no feedback to correct for load changes, fuel quality, or air conditions. Closed-loop control, on the other hand, continuously measures engine speed (or frequency), compares it to the desired set rpm, and adjusts the fuel accordingly to keep the engine running at the target speed. The best statement captures both sides: open-loop uses preset fuel without feedback, while closed-loop uses speed or frequency feedback to adjust fuel and maintain set rpm. This pairing explains why closed-loop can maintain accurate speed under varying conditions, whereas open-loop can drift when conditions change. In practice, the presence of feedback is what differentiates the two modes and enables automatic regulation to a chosen speed.

Understanding how open-loop and closed-loop speed control differ in a marine engine governor is key. Open-loop control sets the fuel input on a preset schedule with no measurement of the actual engine speed—there's no feedback to correct for load changes, fuel quality, or air conditions. Closed-loop control, on the other hand, continuously measures engine speed (or frequency), compares it to the desired set rpm, and adjusts the fuel accordingly to keep the engine running at the target speed.

The best statement captures both sides: open-loop uses preset fuel without feedback, while closed-loop uses speed or frequency feedback to adjust fuel and maintain set rpm. This pairing explains why closed-loop can maintain accurate speed under varying conditions, whereas open-loop can drift when conditions change. In practice, the presence of feedback is what differentiates the two modes and enables automatic regulation to a chosen speed.