Thanks guys for all the input. We had a
Bukh sail drive for years and changed the
engine oil every 100 hours. We always put the
gear shift into reverse when sailing to stop the prop spinning.
We had a
saildrive destroyed by
electrolysis as we unknowingly acted as the anode for a marina which had excessive stray
current. (The marina has now been upgraded with floating pens and all is well).
We now know when the sail drive anode is working as my
captain fitted an anode to the exterior of our
hull and wired the anode through a 50 milliamp scale meter to the
engine. This means we can easily see if
electrolysis is happening when we arrive in different
ports and
anchorages. This simple system saved us yet again when the automatic controller on an impressed
current cathodic protection system failed at a
commercial wharf - we were taking
fuel at the time and we very quickly departed but not before the prop speed had been blown from the tips of the propellor.
Now we are waiting for our new
Volvo propulsion to be installed, so this system will have to be rewired to attach to our new
Volvo saildrive as the volvo saildrive and engine are isolated from each other.
Perhaps this tip may save others from expensive
replacements.
Sue