Packless Shaft Seal (PSS)
There was a thread a while back concerning "cavitation" and vibration noise problems. A survey was done in this forum, and the responses were sent to Catalina Yachts for evaluation in relation to the C350, which has a dripless type shaft seal ("Packless Shaft Seal" aka "PSS"). Catalina has advised that improper maintenance of this type of shaft seal can result in vibration problems. Specifically, the PSS bellows MUST be bled of all air (i.e."burped") after launching the boat. Otherwise, the PSS will be deprived of cooling water. The importance of this cannot be overstated, since a PSS deprived of water will run hot and can cause damage. Even without damage, air in the shaft seal can cause vibration. A water injection unit to the PSS can eliminate potential problems by tapping into the raw water supply to the engine and routing a constant flow of water to the PSS.