Re: Yanmar and dripless shaft seals
The PSS dripless shaft seal
does not need water injection at speeds below 12 kts so it should not be a problem with the prop freewheeling. Not sure about other brands.
Additionally a prop under power will be trying to suck water from the shaft when rotating and this suction is not present when the prop is simply freewheeling thus improving the lubrication when freewheeling.
Mine has never been an issue.
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence