A General Practitioner doesn't perform heart surgery. A Marine Surveyor doesn't rebuild fuel injectors. Knowing when to refer a specialist is critical liability protection.
1. The Engine Survey
When: Any diesel engine over 1000 hours, or any engine with oil sample anomalies.
Why: You can check belts and hoses. You cannot check compression, valve timing, or injector spray patterns. Recommend a "Mechanical Survey by a certified technician."
2. The Rigging Survey
When: Standing rigging over 10 years old. Or any vessel where you cannot inspect the masthead (stepped mast, no bosun's chair).
Phrase: "Standing rigging is of indeterminate age. Visual inspection from deck level only. Full inspection aloft by a rigger is recommended."
3. Fluid Analysis (Oil Samples)
Always. Take samples of engine oil, transmission fluid, and coolant.
Why: High sodium = saltwater in engine. High copper = bearing wear. This is cheap insurance ($30/sample).
Conclusion
Recommending a specialist does not make you look incompetent; it makes you look thorough. It shifts the specific liability to the specific expert.