[C38] Wiring Question

[Tom T.]

The original lighting harness on the Catalina 38 was with either crimped
connected 16 ga or 18 ga. wires that started at the fuse panel and circled
counter-clockwise around the hull at the chine. The lighting harness
dropped under the quarter berth and continued around the top of the hull to
the galley area.
 
That is a lot of length for 16 or 18 ga wire. I rewired my boat with marine
grade 12 ga wire and soldered joints. I also ran a jumper wire from the
fuse panel through the engine compartment to connect to the terminus of the
lighting harness at the galley to make a closed loop harness. This gives
less resistance to the entire circuit, especially the lights on the port
side. By making a loop harness, all lights get about the same voltage.

A loop circuit harness is against wiring codes for a/c circuits but I don't
know if it's illegal for DC circuits.  By making the circuit a loop, you
reduce the wiring resistance greatly.  Use your own judgement, I just know
it works great.  You could always remove  the jumper if you ever sell the
boat or have an electrician work on it.
 
Another energy saving idea is to use a bungee cord to create a neutral helm
when using an autohelm. If you neutralize the helm, it will take very
little current to steer the boat because the autohelm won't have to
overcome the efforts of weather helm allowing  the servo motor to have a
minimal load on it.
 
Previously, on a windy day, you could have burned yourself on my autohelm
servo motor but with a neutralized helm using bungee cords, the motor now
stays cool to the touch and the battery stays hot much longer.
 
Tom Troncalli
The Renata, hull #95
St. Pete, Fla
 


> [Original Message]
> From: Les <hlhowell at pacbell.net>
> To: Catalina 38 Listserve <listserve at catalina38.org>
> Date: 5/14/2008 8:56:09 AM
> Subject: Re: [C38] Wiring Question
>
> Hi, Steve, 
> 	The master switch on the power panel routes the starting current to the
> engine.  Peak this is about 300A.  
> 	I think I used #2 for that run from the batteries to the switch and
> from the switch back to the engine.  If you have the 12V Bible, they
> have some nice calculations in there for that.
>
> 	The rest of your calculations seem OK.  I am running 12ga for the
> lighting when I redo mine, and should be quite sufficient for the runs
> which average about 18' one way.  I would also caution you to use only
> marine grade wire, because standard copper will fail in short order with
> corrosion eating it away at each connection.  Avoid those riveted 3x
> terminal thingies like the plague.  They invariably corrode and cause
> poor connections.
>
> 	The reefer might like a 1% drop, because each bit of drop to a
> motorized device will cause current to go up approximately 2% to sustain
> the load.  This is rule of thumb, but you can look it up in some of the
> books on electrical wiring if you want precise numbers.
>
> 	Also use the terminals that heatshrink with heat glue to seal the
> connections.  It will save you beaucoup problems later.
>
> Regards,
> Les H
> On Wed, 2008-05-14 at 00:07 -0700, Steve Smolinske wrote:
> > I am getting ready to replace some of my wiring and my electrical
> > panels.  I have been drawing up my schematics and would love some
> > input on my calculations and assumptions.  I have based my assumptions
> > on an all night sailing scenario with continous use of systems that
> > would quickly draw down my batteries but conservation is another topic
> > at this time Im more interested in determining proper wire size for
> > peak usage.   Ive assumed that I would be using:  3 cabin lights (4.5
> > amps), Running Lights (2.5 amps) VHF (2 amps), Depth and Knot (2
> > amps), Wind (2 amps), Auto Pilot (1 Amp) Radar (8 amps) GPS (3 amps)
> > Heater (8 amps) and Refrigeration (5 amps) for a total of 38 Amps
> > multiplied by postive and negative wire run length of 15 feet (Battery
> > Cable to the batt switch then from there AWG 6-8 to the pos. bus and
> > from the neg. bus back to the battery) which equals 570 Famps.  Based
> > on the wire charts for a 3% drop this puts me in the 6-8 AWG wire size
> > to and from the batteries.   Any comments on any of these numbers is
> > greatly appreciated.   Refrigeration, Heater and lights are  variables
> > calculated on the high side just to be safe.   
> >  
> > Thanks all, 
> >  
> > Steve
> > Peregrine #312
> > _______________________________________________
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> > Listserve at catalina38.org
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>
>
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