Marine Propulsion

A: That’s the most common mistake — confusing original scantling with rule-required minimum at survey. The difference matters because class renewal limits reference net rule thickness, not what the drawing once said. With drawings in doubt and UT right at the threshold, class can’t lean on operational limits or temporary doublers on primary propulsion members.

A: That’s the most common mistake — blaming oil quality when the time scale doesn’t fit. The difference matters because contamination and fatigue are slow burns. A rapid temperature rise with normal pressure points straight at film collapse from alignment loss, often hull girder related.

A: That’s the most common mistake — trying to tune air or fuel around a propeller law problem. The difference matters because fixed pitch propellers load the engine with the cube of RPM. You unload it by slowing down, not by chasing margins that aren’t there.

A: That’s the most common mistake — reading a capability symbol as physical hardware. The difference matters because double thrust paths would overload foundations. The gearbox symbol often just states it can react thrust if configured that way.