I've reread your original post three times & still can't work it out. First
you say about the two batteries. Then you say something about all positives
are taken from the deep cycle one.
Does that mean you have three all up?
If that is the case then I suggest that the motor has been setup from the
deep cycle one. OK.
The other two sound like they have been setup just for accessories like
fridge, radio, lights etc. OK.
The way they have the switch will be OK for that I reckon as really it is
only used to break the circuit. Doesn't really matter if the earth is broken
or the positive.
As long as whatever the wires are connected to are in the right order it is
OK. I mean positive to the radio positive etc.
The main reason you never see the earth broken on a car is so that if the
device earths out (metal?), it will activate it.
On a car the vehicle is all negative. (earth)
On a boat it is (usually) all wired back to the battery. (both wires)
BruceM


"Tan PS" wrote in message
...
Possibly the switch faulty and works in one position only. With the
switch
out, check that the switch positions work (verify the contacts) before
fitting everything. Saves you the hassle of ripping it out again if it is
faulty.

Tan PS

"Henry" wrote in message
news:51BVb.441665$X%5.5576@pd7tw2no...
I recently bought an O'day 27 and have come across a surprise in the
wiring
of the battery switch.

This is the usual 1,2, both or off.

The two batteries are wired with their positives strapped together, and
the
negatives disappear separately into the switch.
All positives are taken from the deep cycle battery, including the
starter.


Tomorrow I intend to remove the switch with a view to rewiring in a more
conventional way.

Can anyone speculate on why the wiring should be as it is. Also, is
there
anything I should know to prevent blowing the alternator?

Thanks in anticipation

Henry






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