I have just bought a fibreglass sailboat that needs rewiring. Reading
Don Casey's book "Sailboat Electrics Simplified", he states that the
battery MUST be properly grounded to the engine block. That's fine if
the boat has an inboard engine - but does this mean that I have to run
a grounding cable through the boat to the stern and attach it to the
outboard engine? Or is there an alternative "earth" on a fibreglass
boat?

Carl wrote:
I have just bought a fibreglass sailboat that needs rewiring. Reading
Don Casey's book "Sailboat Electrics Simplified", he states that the
battery MUST be properly grounded to the engine block. That's fine if
the boat has an inboard engine - but does this mean that I have to run
a grounding cable through the boat to the stern and attach it to the
outboard engine? Or is there an alternative "earth" on a fibreglass
boat?


Interesting question, Carl.

I don't have a copy of that book so I'm
not sure what Casey had in mind.
Assuming you will have no battery
connection to the outboard (as in
electric starting, battery charging,
etc.), I can imagine no reason why the
engine must be bonded to the battery.

In fact, I can think of a few reasons
why you would not want to bond it.

Good luck.

Chuck

"chuck" wrote in message
...
Carl wrote:
I have just bought a fibreglass sailboat that needs rewiring. Reading
Don Casey's book "Sailboat Electrics Simplified", he states that the
battery MUST be properly grounded to the engine block. That's fine if
the boat has an inboard engine - but does this mean that I have to run
a grounding cable through the boat to the stern and attach it to the
outboard engine? Or is there an alternative "earth" on a fibreglass
boat?


Interesting question, Carl.

I don't have a copy of that book so I'm not sure what Casey had in mind.
Assuming you will have no battery connection to the outboard (as in
electric starting, battery charging, etc.), I can imagine no reason why
the engine must be bonded to the battery.

In fact, I can think of a few reasons why you would not want to bond it.

Good luck.

Chuck

Yea, I would agree. No reason to do this with an outboard if it does not
need an electrical connection. I would install a ground point and run the
battery negative to that. Then you can connect up other grounds without
clogging the negative terminal on the battery. Blue Sea Systems makes a
stud that has a number of smaller connection points arranged around it in a
circle. Quite handy.

chuck wrote in news:1150990018_9283
@sp6iad.superfeed.net:

In fact, I can think of a few reasons
why you would not want to bond it.



Just make sure the outboard has a nice shiny zinc to protect it from being
eaten and it will be fine, electrically.

I also recommend you NOT leave it submerged just sitting there at the dock.
Little creepy crawlers have this great love of tiny cooling system
passageways, the kind between the foot cooling water opening and the top of
the unpumped seawater up inside over the water pump. The little critters
think you're making them an artificial reef and will start CLOSING those
holes for the family....so the next time you start it, there's no water
coming out the ****er in back....NOT GOOD.

Raise it out of the water and if you're storing it for next weekend, FLUSH
IT with the hose ears and dock fresh water. It'll last lots longer!

Carl,
That instruction is only relative to a boat with inboard power.

IF your outboard has a electic start or a battery charging capability,
of course you will need appropriate wire for that. If it does not, you
do not. When my boat had no electric require at the engine, there were
no wires even going there. For the first two sesasons with the electric
start, there was an isolated system with a garden tractor batttery stuck
in the locker next to the fuel tank.

This boat has no external metal and so no ground bond at all and there
are 300+ in outboard version just that way.

Matt Colie

Carl wrote:
I have just bought a fibreglass sailboat that needs rewiring. Reading
Don Casey's book "Sailboat Electrics Simplified", he states that the
battery MUST be properly grounded to the engine block. That's fine if
the boat has an inboard engine - but does this mean that I have to run
a grounding cable through the boat to the stern and attach it to the
outboard engine? Or is there an alternative "earth" on a fibreglass
boat?

Thanks for all the replies which collectively are very helpful. I
didn't make it clear in my original posting that the outboard does have
an electric start so I suppose that it does act as an "earth" - but
presumably only whilst it is in the water. When sailing or at the dock
the outboard is raised. My problem is getting my head around the
concept of grounding connections on a boat (as opposed to land-based
earth connections or vehicle grounds) - but, if I read your replies
correctly, it seems that it is not that important.
Thanks again, everyone.

"Carl" wrote in news:1151090387.562299.34550
@u72g2000cwu.googlegroups.com:

Thanks for all the replies which collectively are very helpful. I
didn't make it clear in my original posting that the outboard does have
an electric start so I suppose that it does act as an "earth" - but
presumably only whilst it is in the water. When sailing or at the dock
the outboard is raised. My problem is getting my head around the
concept of grounding connections on a boat (as opposed to land-based
earth connections or vehicle grounds) - but, if I read your replies
correctly, it seems that it is not that important.
Thanks again, everyone.




The outboard's starting battery isn't connected, or shouldn't be connected
to the AC charger for the house batteries....so there's no reason at all to
"ground" it to the AC line, opening it up to awful electrolysis currents
from all the crap on the docks. I'd want to insure it was fully isolated,
myself. I hate changing zincs.