Answer
Continuous Survey of Machinery is a Class-approved machinery survey arrangement in which machinery items due for Special Survey are surveyed continuously and systematically over the 5-year class cycle, instead of opening and surveying all machinery together at one time.
Generally, about 20% of machinery items are surveyed each year, so that by the end of 5 years all surveyable machinery items are completed. IRS guidance states that CSM allows machinery Special Survey requirements to be completed within a 5-year period.
How many forms are there in CSM?
For oral exam, answer as:
CSM may be carried out in 2 forms:
1. Survey by Class Surveyor
The machinery item is opened up, examined, tested and credited directly by the attending Class Surveyor.
Examples:
Main engine bearings, crankshaft deflection/wear down, air compressors, pumps, coolers, air bottles, safety valves, relief valves, alarms, trips, and other important machinery items as required by Class.
2. Survey by Chief Engineer, later credited by Class Surveyor
Certain machinery items may be opened and inspected by the Chief Engineer, provided he is authorized by Class/company procedure. The Chief Engineer prepares a report with evidence, and the Class Surveyor later verifies records and may carry out operational checks before giving survey credit.
Lloyd’s Register guidance also mentions that, subject to conditions, some machinery items may be credited based on examination by the ship’s Chief Engineer. Bureau Veritas explains similarly that under CSM, machinery items are inspected during the five-year class cycle, with inspection by Chief Engineer followed by confirmatory survey by Class Surveyor.