Full Of Grace: Charlie Finn from Havre de Grace, Maryland, took this shot of his hometown marina with a Nikon D40 digital camera. (Finalist, “Scenics”)
works stiffly after the cable is removed, that’s probably where your
problem is and it might just need some lubrication and cleaning.
Typically these controls are complicated. Last time I disassembled
one, it took me a day to figure it out and a lot of luck getting all the
parts back together. If this part of your system isn’t working well,
it could present a serious safety hazard, so deal with it before you
use the boat. Only take the steps I’ve suggested if you’re confident
you can do it safely and well yourself.
power plug on the dock; it had no grounding. Other plugs on
the dock had grounding, and none of their lower units appeared
unusual. Did the lack of shore-power grounding lead to grounding
into the lake via the outdrive, resulting in electrolysis?
— Jeff Stevenson
Rampant Galvanic Action
I have a 2850 Bayliner, purchased new in 2001. We’ve had
outdrive service performed annually, and at each haul-out the
lower unit appeared as new. However, upon haul-out for outdrive
service this year, the lower unit was corroded, with several deep
pits and loss of metal, and the zincs were fouled with corrosion.
The boat has always been moored in the same slip, under cover in
Lake Washington fresh water. We’ve always used shore power to
keep batteries charged, and to power a small heater/dehumidifier.
When I checked the boat last winter, the heater/dehumidifier was
off; I found the plug-in connection for shore power was dead at the
dock. The marina replaced the plug, and the heater/dehumidifier
worked fine thereafter.
When I saw the corrosion or electrolysis this spring at haul-out, I became very concerned about the damage: much loss of
metal on the thinner parts of the outdrive, lots of pits, and severe
corrosion on the zincs. As part of the outdrive service, the zincs
were replaced. Several weeks later I had another haul-out for
bottom painting, and found the new zincs to again be severely
corroded. It seems that whatever was causing the damage to the
outdrive lower unit was also affecting the zincs. I tested the shore-
Don Casey: That seems to be exactly what’s happening. Some
appliance on your boat — probably the battery charger — connects both to the shore-power AC and to the battery, which
grounds to your engine. Any current “leakage” in a three-wire AC
appliance should find its way to ground via the grounding wire.
Without the grounding wire,
that leakage flows through the
DC ground to your engine
and into the water via the
outdrive, taking metal with it.
As bad as accelerated
corrosion is, there’s worse. If
the normally grounded metal
case of your battery charger or
any AC appliance aboard is or
becomes energized, it represents an immediate and real
risk of electrocution. In addition, the AC flowing into the
water around your boat due
to missing or disconnected
grounding can kill a swimmer, and the problem is made