Question 51 OSE02 - Assistant Engineer - OSV

The Correct Answer is A. **Explanation for A (Once per watch while underway) being correct:** The lubricating oil strainer supporting critical equipment like the main propulsion reduction gear is a duplex or basket-type strainer designed for continuous filtration while the system is operating. These strainers capture contaminants that, if allowed to accumulate significantly, could restrict oil flow, increase differential pressure, and potentially lead to strainer failure or oil starvation. Standard engineering practice and operational procedures (SOPs) for maintaining the health of high-speed machinery lube oil systems dictate that the associated strainers be "turned over" or cleaned frequently. During underway operations, turning the handle "A" (which rotates the cleaning element or rake inside the strainer) once per watch (every 4 hours) is the required minimum frequency to ensure that accumulated debris is scraped off the screen and falls into the sump, maintaining optimal oil flow and differential pressure. This proactive maintenance prevents damage to the reduction gear bearings and gearing. **Why the other options are incorrect:** * **B) Once per month:** This frequency is far too infrequent for critical lubricating oil systems supporting main propulsion machinery while the vessel is underway. Waiting a month would almost guarantee severe clogging, high differential pressure, and potential damage to the lubrication system or the main reduction gear itself. * **C) Once every six months:** This is typically the interval for major preventative maintenance tasks, such as opening the strainer for internal inspection or full basket replacement, not for routine operational cleaning (rotating the handle). As a cleaning frequency, it is dangerously infrequent. * **D) Once per year:** This frequency is completely inadequate for maintaining an operational lube oil system strainer. Annual cleaning would lead to catastrophic failure due to prolonged oil flow restriction.