Re-wiring boat

C

CYQK

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Sep 11, 2009
605
beneteau first 42 kenora
Getting ready to pull wire,most wire will be contained in conduit
Been checking out some applications where the pos. and neg.wire are twisted to eliminate noise.

Has anyone taken the time to twist wires on their boat?
Thks
Gary
 
D

dlochner

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Jan 11, 2014
13,992
Sabre 362 113 Fair Haven, NY
I don't believe twisting pairs is necessary for straight up DC power supply wires. The noise issue is a problem when a signal is passed through the wire, this causes fluctuations in the current which causes the noise. Network cables are shielded which prevents the noise.

A small magnetic field will form around the wires and that isn't an issue except for wires leading to compass lights.
 
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Davidasailor26

Davidasailor26

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May 17, 2004
6,145
Beneteau Oceanis 37 Havre de Grace
+1 for the compass light. Also for wires I added that read the voltage across a shunt to find amperage. Those wires need to pick up the very small (single millivolt) voltage across the shunt and are very susceptible to noise. I've never seen any other DC wires twisted, and for DC I don't think it should make a difference.
 
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G

glaufman

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May 23, 2016
217
O'Day 1984 23 Island Park, NY
Not necessarily necessary, but feels like a good idea to also use twisted pair to power a vhf, stereo, speakers... Maybe digital instruments as well... Come to think of it, if your lights are led or might be in the future, they likely have small power supplies in them, likely smps, so noise can be put out back into the incoming power lines which can radiate... Ymmv
 
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C

CYQK

.
Sep 11, 2009
605
beneteau first 42 kenora
Thks GL
Thats the stuff i was wondering about am using leds and thought maybe this was a good place to twist wires???
 
D

dlochner

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Jan 11, 2014
13,992
Sabre 362 113 Fair Haven, NY
glaufman said:
Not necessarily necessary, but feels like a good idea to also use twisted pair to power a vhf, stereo, speakers... Maybe digital instruments as well... Come to think of it, if your lights are led or might be in the future, they likely have small power supplies in them, likely smps, so noise can be put out back into the incoming power lines which can radiate... Ymmv
Click to expand
LED noise is an issue if you use poor quality LEDs. If you go down the LED route, be sure to buy high quality constant current LEDs. See this article https://store.marinebeam.com/constant-current-1/

With good LED technology, the current draw is very low, any radiated noise is going to be extremely weak.

If you rewire the boat using multiple negative bus bars, then you will have many positive wires running through the boat without the corresponding negative wire.

Power wires near compasses need to be twisted, others don't. There are apps that measure magnetic fields. Get one and check the magnetic fields generated by your boat. Power up some devices and measure the fields before and after the power is on.
 
G

glaufman

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May 23, 2016
217
O'Day 1984 23 Island Park, NY
Constant current does t mean no emi, or edn improved emi for that matter... While the simple resistor route in the article will be terribly inefficient and inconsistent, it does not produce the switching currents that emit emi... Any smps will... The article talks about waveshaping but doesn't go into details... I was unable to find their emi page referenced... But even a resonant converter produces current steps that generate emi...
Mind you, I'm not saying he twisted pair is necessary here, but it seems to me a good idea as to progresses each new device produces noise... It's just a matter of hese combine and eventually it .starts messing with something... When's the last time anyone checked their vhf transmission for noise at the receiving end?
 
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