What Should Bow light voltage be?

[er9]

So my bow light does not work. It very old and corroded as are all the wires in the mast/bilge area where i beleive the light crosses paths before going to AC panel.

bulb was checked with multi tester and is good. connections are really poor and corroded though. those will get cleaned up next weekend.

question is...i'm assuming if i set a multi-tester to test for AC, put a probe on each wire i should get a reading of something slightly under 120 volts since its connected to the AC side of the panel. am i correct in my assumption or since there is only one ground and one hot wire would multi-tester even be effective? do i put both probes on the hot wire? Still trying to learn how to use one of these things.

The reading i received with tester was something like .297 or something like that, sorry forgot to write it down.

[a64pilot]

What do you mean Bow light?
Maybe just my boat, but I have no AC lights, all lights are powered off the battery bus, 12VDC.

First your multimeter will most likely have both an AC and a DC selection, and a red and a black wire, usually the black is negative and the red positive, but don't worry too much as if you get them backward it will read as negative numbers.

Before working too much with AC current, you may want to become a little more familiar with it as it can hurt you, maybe even kill you. Be double sure power is removed from an AC circuit before you touch it and there have been provisions made so that someone can't inadvertently power the system.

With AC, you are playing with fire, be careful.

[exMaggieDrum]

Not sure what kind of boat you have but most navigation lights are DC, not AC. So set your multimeter to DC and retest. It should be close to battery voltage (but less due to normal resistance in all wiring especially far from the batteries). If the wires are that corroded, if it were my boat, I would cut them back to a dry place and then splice in new wiring to the light, using tinned marine wire and tinned terminals (all heat shrink kind if you can). Don't try to clean the wire at the ends if it is corroded as you make it sound. If it should normally be a dry space, try and seal it from water. If in a normally wet location (like an chain locker) attach the wires up as high as possible and away from the hawse pipe. Put in a drip loop at the light fixture itself so water will tend to drip down it instead of flowing to the fixture. That will also give you extra wire to cut back in the future if needed.

[mcarling]

I've never seen AC navigation lights on any boat. It's not impossible, but it seems unlikely. What type of boat is this? What is the source of continuous AC power while at sea?

[nigel1]

I think his boat is a Mariner 36.
Very likely to be 12 volt DC.

[er9]

Originally Posted by a64pilot

What do you mean Bow light?
Maybe just my boat, but I have no AC lights, all lights are powered off the battery bus, 12VDC.

First your multimeter will most likely have both an AC and a DC selection, and a red and a black wire, usually the black is negative and the red positive, but don't worry too much as if you get them backward it will read as negative numbers.

Before working too much with AC current, you may want to become a little more familiar with it as it can hurt you, maybe even kill you. Be double sure power is removed from an AC circuit before you touch it and there have been provisions made so that someone can't inadvertently power the system.

With AC, you are playing with fire, be careful.

the red and green bow light.

i dont understand boat electrical yet but the switch panel where all the boats wiring for components comes together where you can switch on and off individual components. on my boat it has an AC side and a DC side. on the DC side there is four switches, water heater and outlets. on the AC side of the panel are all the navigation lights, auxiliary switches, electronics etc...but knowing house outlets are all AC it confuses me why they are on the DC side of the panel. I wish i could get to the boat and take a pic of panel....didn't think of it while i was there this weekend.

in my ignorance I assume those are all AC current but this is my first boat and i really have no clue about electrical.

How do you 100% remove power from AC circuit? I know enough to unplug shore power when working on electrical. i dont fully know what turning the battery selector switch to "OFF" position does for cutting power. how else do i cut power aside from disconnecting batteries?

[Cheechako]

You’ve got your sides switched, maybe the panel marking is unclear? The water heater and outlets etc are AC. The lights etc are DC. Measure the bulb contacts on the bow light (DC) and see how much voltage drop you have. It might be real low indicating a bad wire or connection.
I highly recommend you read up on boat electrical. A Nigel Calder book would be a good resource.

[nigel1]

Originally Posted by er9

on my boat it has an AC side and a DC side. on the DC side there is four switches, water heater and outlets. on the AC side of the panel are all the navigation lights, auxiliary switches, electronics etc...but knowing house outlets are all AC it confuses me why they are on the DC side of the panel. I wish i could get to the boat and take a pic of panel....didn't think of it while i was there this weekend.

I think that this is a case of the panel being incorrectly labeled, or you may not be remembering correctly.
The water heater and outlets will be on the AC side of the panel.
Lights. electronics, pumps etc will be on the DC side.

[er9]

Originally Posted by exMaggieDrum

Not sure what kind of boat you have but most navigation lights are DC, not AC. So set your multimeter to DC and retest. It should be close to battery voltage (but less due to normal resistance in all wiring especially far from the batteries). If the wires are that corroded, if it were my boat, I would cut them back to a dry place and then splice in new wiring to the light, using tinned marine wire and tinned terminals (all heat shrink kind if you can). Don't try to clean the wire at the ends if it is corroded as you make it sound. If it should normally be a dry space, try and seal it from water. If in a normally wet location (like an chain locker) attach the wires up as high as possible and away from the hawse pipe. Put in a drip loop at the light fixture itself so water will tend to drip down it instead of flowing to the fixture. That will also give you extra wire to cut back in the future if needed.

1980 Mariner 36. almost all the wiring foreward of the distribution panel runs across the top of the bilge. i think the bow light wire then runs forward and up the port wall in the v-berth, up into the bow pulpit forward to the light mount. its a serious mess. half of the wiring that runs up the mast was crumpled into a loose ball and stuffed in the bilge at base of mast which was under water for some time. most of the rubber protective coating over the wire is coming off. the steaming light does not work, bow light does not work but surprisingly anchor light works. unfortunately re-wiring the mast and replacing the wire will have to wait. i just need to get it working temporarily to get the boat to new marina. i dont plan to sail at night but i want the lights working just in case.

i was going to cut the loose ball of wires down and remove the extra wire hanging in the (now dry) bilge, cut back to clean wire, put new connectors on, heat shrink tube the ends, replace and re-wire them into a new terminal block and connect them securely to the top of the bilge until i have the time to re-wire and re-position them.

[er9]

Originally Posted by mcarling

I've never seen AC navigation lights on any boat. It's not impossible, but it seems unlikely. What type of boat is this? What is the source of continuous AC power while at sea?

yeah good point. none that i know of. 1980 Mariner 36 (peter canning mariner).

[a64pilot]

Originally Posted by Cheechako

I highly recommend you read up on boat electrical. A Nigel Calder book would be a good resource.

I second this recommendation, don't do anything until you do some reading, or find a knowledgeable friend, maybe even hire an electrician to explain things

[er9]

Originally Posted by Cheechako

You’ve got your sides switched, maybe the panel marking is unclear? The water heater and outlets etc are AC. The lights etc are DC. Measure the bulb contacts on the bow light (DC) and see how much voltage drop you have. It might be real low indicating a bad wire or connection.
I highly recommend you read up on boat electrical. A Nigel Calder book would be a good resource.

i think they may have mis-labeled the distribution panel and thats why i'm so confused. i'm absolutely certain all the lights and instruments are on the side of the panel that has 'AC' engraved in big letters at the top of the panel. On the right side are the four switches for water heater and outlets as well as the big red battery selector switch. there is an engraved line seperating the two sides on the panel and on the right side has 'DC' engraved in big letters at top of panel. wish i could get to boat to take picture. cant find one online either.

i will try and test for DC next weekend.

thanks for the book suggestion. going to buy it right now and read it.

[er9]

Originally Posted by a64pilot

I second this recommendation, don't do anything until you do some reading, or find a knowledgeable friend, maybe even hire an electrician to explain things

much thanks going to do both, water and electricity scares me. since i'm so ignorant of electrical i think those suggestions are wise.

[unclemack]

Videos of multimeter tutorials on YouTube might help with a basic understanding of their safe use.

Videos of boats on fire - and there are pages and pages of those - show just one of the dangers of people making mistakes with boat electrics.

[hellosailor]

There's no telling what or why someone did something on a panel. They might have rewired at some point and just decided "Well, these breakers fit better on that side, so we'll put them there."


DO make sure that all sources of AC, all shore power, any inverter, etc. are physically turned off and preferably unplugged, before you go testing the circuits. If you accidentally touch a live 12VDC line, unles you're making a dead short on a battery cable, odds are nothing will happen to you. Although you may blow a fuse.


On the other hand, if there's full AC power when you're not expecting it, you may not survive the shock.


Don't be shy about drawing a schematic with a pencil and a large pad of paper, or about using masking tape (that's what we call it in the states, tan paper crepe tape used for masking off painting areas) or something similar and a permanent marker, or a label maker, to put actual labels on wires, either.