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Old 23-12-2013, 21:15   #1
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32 volt, 12 volt, 120ac

quick question about grounding and lighting protection....

i just aquired a rather large boat designed by Bill Tripp in 1967, lanched n 1969, for a famiy that was rather well off back then. its 57' built in a german ship yard, solid glass, has stainless centerboard just aft of the mast and another bronze centerboard just under mizzen. pretty neat setup. weighing in at 70,000 lbs. neadless to say, its a big boat 6' board up, 12' board(s) down. ther have been about 4-5 owners over the years, all seemed to be radically engineer minded.

so off to my main question. I have 12 and 32dc voltage and 110 ac and maybe 220 for the heatpump, still digging, not sure yet.

some keel boats have threaded holes in them. there are copper strips and hard wire in the boat that looks like lighting and grounding.

so the engine is a newer 170hp turbo yanmar, 12 volt starer with a 12 volt and 32 volt alternator (not installed) . so the grounds are the same right? does it need to be grounded to the llighting system? then on the ac side does the green (earth) wire hook in there somewhere?

I'm good with 12 volt, but all this other stuff makes my head spin a bit. there are 4 8volt batteries for the 32 side and 10 6 volt for the 12 volt side. ac is 2 30 amp cords..

help please!!

Ryan
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Old 24-12-2013, 00:44   #2
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Re: 32 volt, 12 volt, 120ac

The DC grounding is all the same but you will need to use cabling large enough to maintain voltage for the 12 volt system even though the 32 voltl system may not need the larger size.

Assuming you mean 2 x 30 amp cords at 120 volts you will not have 240 volts aboard. If you want that you will need to change to a single 240 x 50 amp cord which is not a bad idea if you are the USA but everyone has their own ideas about that. If what you have is working nothing wrong with it.

The earth does come into play. The way I explain it is your boat is like any other appliance that uses 120 volts. All its metallic components should be grounded to eleminate electric shock hazard. When you connect the AC green ground to the DC negative buss you provide safety. AC faults to DC equipment will trip the offending circuits breaker.

I assume you mean lightning system by llighting system? It serves two purposes. It does provide a bit of protection from lightning. In most boats today it is referred to as a bonding system. With all the metals you have underwater connecting them together and to a bar type zinc may be in order. Connecting all your underwater metals together then to a zinc gives them something to chew on besides each other. This system is also supposed to connect to the DC negative buss. Now you have the DC negative, AC green ground and bonding systems connected. Your appliance (boat) is fully protected.

Lastly consider installing a galvanic isolator on your AC green ground where it comes aboard if you don't have one already or transformers. It will help reduce the chance of bringing stray current aboard while using shore power.
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Old 24-12-2013, 01:19   #3
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Re: 32 volt, 12 volt, 120ac

Quote:
Originally Posted by rrayfield View Post
quick question about grounding and lighting protection....

i just aquired a rather large boat designed by Bill Tripp in 1967, lanched n 1969, for a famiy that was rather well off back then. its 57' built in a german ship yard, solid glass, has stainless centerboard just aft of the mast and another bronze centerboard just under mizzen. pretty neat setup. weighing in at 70,000 lbs. neadless to say, its a big boat 6' board up, 12' board(s) down. ther have been about 4-5 owners over the years, all seemed to be radically engineer minded.

so off to my main question. I have 12 and 32dc voltage and 110 ac and maybe 220 for the heatpump, still digging, not sure yet.

some keel boats have threaded holes in them. there are copper strips and hard wire in the boat that looks like lighting and grounding.

so the engine is a newer 170hp turbo yanmar, 12 volt starer with a 12 volt and 32 volt alternator (not installed) . so the grounds are the same right? does it need to be grounded to the llighting system? then on the ac side does the green (earth) wire hook in there somewhere?

I'm good with 12 volt, but all this other stuff makes my head spin a bit. there are 4 8volt batteries for the 32 side and 10 6 volt for the 12 volt side. ac is 2 30 amp cords..

help please!!

Ryan
Treat each system as autonomous;

12volt supply+, returns to 12volt -.

32 volt supply +, returns to 32 volt -.

120 volt supply Line voltage, returns to Neutral, Green safety/earth wire returns to shore power.

Bond each system together at one place(only) "Ships Ground/bus bar" ='s.

12 volt bat. neg/-. to

32 volt bat neg/-. to

120 volt green safety. to

"Bus Bar/ships ground" to engine/prop/ or underwater bonding plate.

Caution, Isolation transformers, UW Metal Bonding, lighting, and RF need additional Information.

Follow the instructions if using a Galvanic Isolator.

Lloyd
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Old 24-12-2013, 01:43   #4
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Re: 32 volt, 12 volt, 120ac

Ryan, I have ask what runs off 32v dc? We used to borrow a RN Fleet tender for diving that was wired like that. 12v, 24v 110v and 240v. After 40 odd years of RN refits the wires were all painted the same colour and you never quite knew what voltage was in what plug, it was a bit of a nightmare.

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Old 24-12-2013, 19:26   #5
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Re: 32 volt, 12 volt, 120ac

Thanks for the replies and MERRY CHRISTMAS!

So if I have it all correct in my head I should start with the bonding system at the bow (stainless steel Pulpit where headstay attaches) running alot and conect to mast and outter stays, then continuing aft it needs to connect to a keel bolt (which connects to lead which connects to zinc) then onto stainless water tanks (4) and 1 stainless diesel day tank(1) (the other fuel tanks are intergral) coming further aft connect to engine and generator stringers, or block?? then further aft to mizzen mast and outer mizzen stays then onto the rudder post. the rudder is stainless steel with zincs. (Whew!!!)

after that is complete I should create (somewhere in the line) a ships Ground buss. Which would connect the DC negatives and the AC green earth ground wire...)?? add a galvanic isolator on the green earth wire on shore side of buss.

Am I on the right track?

The only thing that bothers me is that green ac earth wire.... What if the dock I plug into is wired wrong? would it energize the Bonding system and blow some breaker? or burn up my DC side? Is there protection from this? ac on boats makes me nervous... I know its everywhere and I have to have it but.....
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Old 24-12-2013, 19:39   #6
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Re: 32 volt, 12 volt, 120ac

I will only comment on the galvanic isolator. I'm surprised that a ship like that doesn't have an isolation transformer. Isolation transformer is far safer than a galvanic isolator and will serve you well.

P.S.: With such a complicated system I think you would be wise to hire a qualified marine electrician to consult with and help you sort it out. Its very difficult to do on the internet where you will get bits and pieces and conflicting views all at the same time.
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Old 24-12-2013, 20:03   #7
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Re: 32 volt, 12 volt, 120ac

Ping me if I can help with the 32v stuff
I have a lot of experience with Hatts and 32v Chris Crafts/etc
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Old 24-12-2013, 20:12   #8
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Re: 32 volt, 12 volt, 120ac

Merry Christmas !!!!

I have a 46.6 foot 1982 Bertram motor yacht. I just installed all new engine banks. They are 32v (four 8v batteries in series). Bilge pumps and fresh water pumps are about the only items around that can be found for 32v systems.

According to the manual that I downloaded from the Bertram website. The 32v is only grounded to itself. The 12v battery bank for the generator is the same. The 32v and 12v negatives are NOT connected at all.

I will assume the 32v does get some type of ground via the engines, as it is connected to the starters and alternator, and the 12v must do the same at the generator.

I have kept it this way. There are several opinions if that is good or bad, but it seems to be working on the Bertram !

I have separate solar panels for each bank, and I do not have any additional lightning protection. I am thinking that the flow of a lightning strike would travel down to the engines thru the actual negative from the panel. I have 16mm2 cables from the panels to each controller (the 32v controller shuts off at 34v and keeps a good 33.6v float voltage so far, I may need to change that in the future).

As I am unable to find an inverter that will work on 32v. I may add a 24v bank and solar panels to have a 3,000w inverter (I have room for a few more panels on the Fiberglas flybridge hardtop I made). I would think that grounding would be made at the inverter for that.

Have a very Merry Christmas !!!

Alan
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Old 24-12-2013, 21:16   #9
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Re: 32 volt, 12 volt, 120ac

You might want to look into eliminating the 32 volt system all together. The biggest expense in converting a 32 volt boat to 12 or 24 volt is the cost of new starters and alternators. You've already got that expense taken care of. Take a look at your equipment and see if any of it would need to be replaced. Take a look at the size of the wires. Would any of them need to be larger? It might be worth the effort and expense to eliminate the 32 volt system and standardize on 12 volts for your DC system.
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Old 25-12-2013, 04:11   #10
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Re: 32 volt, 12 volt, 120ac

Nigel Calder's book "Boatowner's Mechanical and Eletrical Manual" would be a good read to understand all this better. If the boat has lasted this long without serious issues I wouldn't be in too big a hurry to start changing things. Some of it may be taken care of in ways you haven't yet observed.
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Old 25-12-2013, 08:33   #11
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Re: 32 volt, 12 volt, 120ac

Hello,

rratfield had very good question, and as I have an older vessel as well. I tend to follow the "if it ain't broke, don't try to re-invent the wheel" attitude !!!

The bonding strips for the AC and replacing all the seacock wires to the bonding strips is very important !!! In 2 weeks we go to the slipway for all the seacock's and new bonding wires !!!

As I have lead acid cels for the 32v banks, AGM for the 24v, and will have GEL for the inverter/main house bank. Only time will tell to their true efficiency !!!

Just can't see the value in lifePO batteries as I mainly use solar yo recharge my banks !!!

Alan

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Old 26-12-2013, 17:38   #12
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Re: 32 volt, 12 volt, 120ac

Hello,

Correct me if I am wrong...

Looking at the 570hp Detroit Diesel engines this morning to see about switching over to 24v from 32v. I would be able to simply change the solenoid on the starters (no need to change the entire starters), and then install new 24v alternators.

Has anyone done this ?

Alan
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Old 26-12-2013, 18:22   #13
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Re: 32 volt, 12 volt, 120ac

Changing from 32 to 24v is fairly common. Traditionally you DO have to rewind the starters as well as the alternators. You may also have to step up a lot of the distribution wire or switch to lower current lights. Some Hatteras' have 10awg everywhere and can handle the lower voltages; other boats need to switch to LED lighting and replace some wiring to keep voltage drop down and meet insulation requirements.
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Old 26-12-2013, 18:32   #14
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Re: 32 volt, 12 volt, 120ac

I have heard that is the case. Some of the old Huckins here in Jacksonville that have had significant refits also changed their 32 volt systems to 24. You may also have to change the stop solenoid. Don't forget about your gauges unless they are mechanical in which case only the bulbs will need changed.

One of the big reasons for switching from 32 to 24 volts is there is a larger variety of electrical equipment available for 24 volt systems. If you are doing a refit and it happens to include rebuilding a lot of stuff with 32 volt DC motors such as heads, windlass, etc the voltage switch makes sense. Especially if you repower and the engines are electronic 24 volt types. Dosen't make sense to keep 12, 24, 32, 120 & 240 volt systems and all the different battery banks, chargers, etc. as long as the wire size supports the lower voltage.

If you are seriously considering I can make some calls and check for you.
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Old 26-12-2013, 18:41   #15
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Re: 32 volt, 12 volt, 120ac

Hello,

Great info... Engine voltage is my main focus at this time.

All the lights are already 12-36v LEDs, and all the lighting wires are 14AWG, bilge pump wires are 12AWG, and 10AWG for both heads. Good to go in that area for 24v. The fresh water pumps are currently running off the 32v and have 12AWG to them. Depending on motor size, I may change that wire to the pump as to keep the 7GPM as the current 32v fresh water pump !

It will be a relief to have 24v... 32v gear is not readily available around me, or is twice the cost of 24v hardware !

Now to find reliable and affordable alternators and starters after the new year.

I have a good foundation for a change over !!!

Thanks,

Alan
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