BoatHowTo · video

What this video covers

A synthetic flexible shaft coupling between a transmission and propeller shaft likely breaks the electrical path used for grounding, Nigel Calder confirms.0:43 The fix is straightforward: run a wire strap across the coupling to restore continuity, or establish a separate grounding path through another underwater metal fitting on the boat.1:09 Calder also notes a reason to keep the drivetrain isolated — the propeller shaft and propeller can be managed as a separate corrosion zone with their own anodes.1:25 The more critical warning concerns Volvo Penta sail drives, which are deliberately isolated from the engine via a plastic gasket and plastic bolt inserts.1:38 Bridging that isolation on a Volvo Penta sail drive significantly accelerates corrosion on the unit.1:52 Calder cites workshop examples where broken isolation caused exactly that damage.2:08 Anyone experiencing unexplained sail drive corrosion should check whether that factory isolation has been compromised.2:18

More from BoatHowTo

How to keep you TANK CLEAN in the days of BIODIESEL.. | Ask The Expert with NIGEL CALDERAug 2026PARALLELING Conductors for AMPACITY - is that SAFE?? | Ask The Expert with NIGEL CALDERAug 2026ENGINE OIL turns BLACK right after Oil Change?? | Ask The Expert with NIGEL CALDERAug 2026Same LAYUP RECOMMENDATIONS for FAME and HVO bio diesel? | Ask The Expert with NIGEL CALDERAug 2026

From BoatHowTo — see the channel’s boat, crew, and every analysed video.

The Sailing Directory Newsletter

One email with the fleet's best finds — the moments, boats, and stories worth your watch time. Enter your own address to get your own copy.