Conference vicki::boats

    On my boat there is a single ground stud behind the instument cluster.
    Each of the instrumnets and switches is individually grounded to this
    stud per the boat manual's orders.  This ground point is connected back
    to another ground 'point' on the engine which serves as the main ground
    connection.
    
    Now my boat is alot smaller than yours, but I'm sure that electically
    the layout is basic.  You probably have more points scattered about the
    boat.
    
    
    I would start at the control panel with a VOM meter and look for a
    voltage loss and/or high resistance from the offending switches to 
    PAST the local ground points, then move back thru the grounding circut 
    checking for the same and looking for loose or corroded
    connections (especially those contained within those big rubber coated
    plugs).  The electrical diagram will help alot here.
    
    I think you're on the right track suspecting grounding problems, and
    if you're patient and methodical you'll find it. 
    
                                              Good luck
    
                                                 Tom

    
      If other things go on(in addition to the one you want) when you
    operate a switch, then it's VERY likely that an open ground is your
    problem.
       The other instruments are supplying a (poor) ground for the device
    you turned on.
    
       So check your grounds, not your plusses :^)
    
    					Kenny

    Frank,
    
    I also have a Bayliner, but its a 1981 Explorer.  I agree, your problem
    is probably a broken ground somewhere.  You may find it useful to purchase
    the 12 volt Doctor's Practical Handbook by Edgar Beyn.  I had a very
    obscure problem last summer and the book helped me diagnose it in just a few
    minutes.  Even though they get $25 for the book, I consider it
    invaluable.
    
    You can order it by calling Spa Creek Instruments at 301-267-6565.
    
    Regards,
    
    Ted
     

    Thanks for all the usefull information.  I will pick up a copy of
    the book tommorrow.  I appreciate the pointer.  Compared to $47.00
    an hour for a marine mechanic, it is still a good deal.
    
    I will be removing the boat cover this week end, unless there is
    a weather prediction that we may be getting snow.  I will install
    one of the batteries and see where I can follow the ground wire
    for a bad connection.
    
    In the meantime, any other responses, ideas or whatever will still
    be appreciated.

    Re: .3  
    
    I picked up a copy of The 12 Volt Doctor's Practical Handbook
    at Boats/U.S. in Waltham (for $22).  It is well worth the investment.
    
    Thanks for passing the information along.

    Moved by moderator.  See reply .5 for a good source of info.
    
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Note 1052.0                   wire size guidelines                    No replies
MIZZEN::DEMERS                                       13 lines  21-APR-1993 15:11
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Hmmm - checked around and suprised not to find an topic on this...

I'm looking for the rules for wire guage.  While I'd like all the rules, 
I'll save that for the library...Can anyone recommend a good reference?

Specifically, what's the minimum size for a wire that will be ~3' in length
and will carry a max of 9A at 12V?


tnx,

/Chris

    The following guidelines were in SEA Magazine:
    
    For 10 to 15 feet in lenght:
    
    Gauge        Current in Amps
    20           1.5
    18           3
    16           6
    14           15
    12           20
    10           25
    8            35
    6            50
    4            70
    2            90
    0            125
    00           150
    
    They added a general rule: for every 10 feet beyond that go up in
    size(smaller number).

    Re: -1
    
    Guidelines are sometimes misleading. A better way to reconcile which
    wire size one should use is to understand the voltage drop caused by 
    the wire. Also note, the distance  between the source (battery) and 
    the load is twice the measured distance between the source and
    the load because the wire has to provide a return path.
    
    
    This may be of value to help with your decision:
    
    	wire size		ohms/1000 feet
    	 8			.00063
    	 9			.00079
    	10			.001
    	11			.00126
    	12			.00159
    	13			.002
    	14			.00252
    	15			.00318
    	16			.00402
    
    Joe