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Old 09-26-2013, 12:14 AM   #1
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Shore Power Configuration

Folks, Just another newbie to power boating dumb question! My 1972 Gulfstar 36 Trawler has two primary AC circuits, each served by its own exterior 30 amp receptacle. Obviously I can use parallel shore power cords, provided two hook ups are available. I have seen splitters that allow one cord to be connected to both receptacles. How does that system work? Is the single cord 50 amp, split to two 30 amp cords or is it a single 30 amp circuit split? I have air conditioner units on each AC circuit and if in use would have to monitor current loads carefully. Help! gts1544 - George
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Old 09-26-2013, 01:10 AM   #2
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Folks, Just another newbie to power boating dumb question! My 1972 Gulfstar 36 Trawler has two primary AC circuits, each served by its own exterior 30 amp receptacle. Obviously I can use parallel shore power cords, provided two hook ups are available. I have seen splitters that allow one cord to be connected to both receptacles. How does that system work? Is the single cord 50 amp, split to two 30 amp cords or is it a single 30 amp circuit split? I have air conditioner units on each AC circuit and if in use would have to monitor current loads carefully. Help! gts1544 - George
Your boat is set up similar to ours- major loads on one leg, and secondary loads on the 2nd 30A circuit

I'm sure I'll be corrected if I'm wrong The 50A cord split to feed both 30A inlets is still just 50A total, so you will have to manage you loads. If you use a splitter on a 30A tower to feed 2 30A inlets, you will have to mange those loads that much more carefully.
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Old 09-26-2013, 01:12 AM   #3
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Old 09-26-2013, 05:18 AM   #4
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If you will be spending much time dockside an upgrade to the 240/50 power hose and inlet might be worthwhile.

If you cruise the 30A are far easier to drag out to hookup.
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Old 09-26-2013, 06:44 AM   #5
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Peter

I may be wrong, but if you use a splitter from a 50 amp shore power tower the issue is whether the shore power is 50 amp 110 volts, or 50 amp 220 volts (North American). If it is 50 amps 110 volts then the boat will receive only a total of 50 amps. If it is 50 amps 220 volts than the boat is actually receiving 50 amps on each shore power inlet - limited of course by the boats 30 amp fuse.

In North America our 220 volt systems are actually two 110 volt "legs" which can then be split either at the tower or once on the boat. An explanation of the "legs" is that instead of one hot wire (with 110 volts) you have two hot wires each with 110 volts.

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Old 09-26-2013, 06:59 AM   #6
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Folks, Just another newbie to power boating dumb question! My 1972 Gulfstar 36 Trawler has two primary AC circuits, each served by its own exterior 30 amp receptacle. Obviously I can use parallel shore power cords, provided two hook ups are available. I have seen splitters that allow one cord to be connected to both receptacles. How does that system work? Is the single cord 50 amp, split to two 30 amp cords or is it a single 30 amp circuit split? I have air conditioner units on each AC circuit and if in use would have to monitor current loads carefully. Help! gts1544 - George
I think I know your problem...are you asking if there is only ONE 30 amp receptacle on the power pole/dock...how do you get power to both 30 amp panels in the boat?

Yes they do make a splitter that splits a single 30 amp outlet to 2 - 30 amp legs so you can power both 30 amp panes inside...wow!!!! as far as power management goes.

Another alternative is to just wire a "source selection" breaker inside that allows you to power the second panel either from a shore power cord or the first breaker panel...easier than a second cord hookup...but does require more thought for installation.

I am doing what the other suggested...upping to a 125/250 power cord...but that involves a lot of rewiring work and some think it limits you as to where you tie up...(I have also found the opposite true where transients ONLY get a 125/250 50 amp outlet)...the reason I want to upgrade is I am a liveaboard and like to NOT have to power manage....if you don't stay onboard a lot and have a lot of 110V needs then stay with the 2-30's and just get the 30 to 2-30's splitter.

http://www.defender.com/product3.jsp...037&id=1353775
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Old 09-28-2013, 05:31 AM   #7
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> I am a liveaboard and like to NOT have to power manage..<

Thats why load shedding was invented , for most it operates invisibly with no loss of any services.

Load shedding or very careful power management is REQUIRED if 2 -30A legs are powered off a single 30A power hose.
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Old 09-28-2013, 06:24 AM   #8
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Whether load shedding is manual or auto...it's still load shedding....it has to turn something off that I don't necessarily want off at that moment.

yes...living on a single 30 is a pain...can be done but you better know your systems and be ever vigilant to what other aboard are doing!!!
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Old 09-28-2013, 06:30 AM   #9
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An alternative to power management. From time to time faced with shore power sources insufficient for the boat I wired the boat to make use of the shore power on a 24 hr basis and to power the boat from the inverter / battery banks. Thus the boat's usage over the level of the shore power was made up for by the inverter and the batteries were recharged during the night or off hours when the usage was lower. This worked well even when the shore power was only 15 amps (110 volt). Of course this precluded using the AC or the electric heaters.

Many inverter/chargers will do this automatically. If not it can be manually done by wiring an additional 30 amp shore power inlet with a dedicated outlet box for the inverter/charger and putting a plug on the inverter/charger so that you can manually switch sources.

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Old 09-28-2013, 09:45 AM   #10
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An alternative to power management. From time to time faced with shore power sources insufficient for the boat I wired the boat to make use of the shore power on a 24 hr basis and to power the boat from the inverter / battery banks. Thus the boat's usage over the level of the shore power was made up for by the inverter and the batteries were recharged during the night or off hours when the usage was lower. This worked well even when the shore power was only 15 amps (110 volt). Of course this precluded using the AC or the electric heaters.

Many inverter/chargers will do this automatically. If not it can be manually done by wiring an additional 30 amp shore power inlet with a dedicated outlet box for the inverter/charger and putting a plug on the inverter/charger so that you can manually switch sources.

Marty
Good post!

What you pointed out is a feature of inverter/chargers that most people do not realize exists. If you set the inverter/charger for say 10 amps then it will supply the loads off of the battery bank if they exceed 10 amps AC. This is a great way to supply a transient load like a microwave or trash smasher.

Another method is to use your generator. When sitting dockside and wanting to use more devices than the 30A shore power will supply, the generator comes in handy.

Most/many generators do not seem to get enough use as it is, and if used frequently will last many thousands of hours, something over 20,000 hours for a well built unit.
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Old 09-28-2013, 10:35 AM   #11
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If you could post a photo of your panel that would make informed suggestions/explanations easier.

In my opinion:

1. There is no advantage to reworking to use a single 240/50A cable.
2. Marinco and others offer a relatively modest priced splitter from a single 240v/50a outlet to a pair of 120v/30a cables. This should be a part of your cruising gear since some docks may only have a 240v/50a outlet available. this gives you 50a on each cable but your inboard 30a breaker will limit the power and protect your 30a cables from overheating. Same total power as if you had plugged in to two 30a outlets.
3. Marinco and others also supply a splitter from a single 120v/30a outlet to two 120v/30a cables. Of course you only have a total of 30a available but at least both your panels will be powered and you will have access to all your circuits. You should have one of these,too.
4. Marino and others also have a 120v/15a (normal household outlet) to 120v/30a. In the worst case, you can get at least 15a to your panels when combined with #3 above. We once left our 65' Florida Bay Coaster "Key Largo" parked a month in Annapolis with only a single 15a powere source - it was enou to keep the refrigerator going and batteries charged.
5. Don't bother with a 120v/50a adapter/splitter. These outlets are rare at marinas - at least in my experience.

How do you combine your panels when using the generator? Depending on how your panels are wired, you may be able to combine them already lowered by a single cord?

None of what I say has to do with power management, something others have done a good job of explaining. All boaters need to do this regardless of the size of their generators and shore power cabling - a crushing yacht is not a home fed by a 200a cable.
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Old 09-29-2013, 08:48 AM   #12
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In my opinion:

1. There is no advantage to reworking to use a single 240/50A cable.


And in fact, there's a potential disadvantage: a 50' 50-amp/240v power cable weighs in the neighborhood of 50 lbs... and humping that around is not at all like connecting two 30-amp cables.

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Old 09-29-2013, 09:41 AM   #13
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I'd rather hump the heavier cable a little and have 100 amps useable than run back and forth to the CB panel to load shed or be in the middle of something and have something auto load shed because I only have 60 amps available...

And yes I know I'll need a different CB panel.....

And for those that don't think real cruising yachts need that kind of power never tie up at big docks and see the electrical services there....sure we like out primeval quiet anchoring time...but there are times 5 star accommodations are nice too.

Different strokes folks.....
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Old 09-29-2013, 11:17 AM   #14
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5. Don't bother with a 120v/50a adapter/splitter. These outlets are rare at marinas - at least in my experience.
They are fairly common on the Great Lakes.
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Old 09-29-2013, 02:08 PM   #15
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I'd rather hump the heavier cable a little and have 100 amps useable than run back and forth to the CB panel to load shed or be in the middle of something and have something auto load shed because I only have 60 amps available...

And yes I know I'll need a different CB panel.....

And for those that don't think real cruising yachts need that kind of power never tie up at big docks and see the electrical services there....sure we like out primeval quiet anchoring time...but there are times 5 star accommodations are nice too.

Different strokes folks.....
Your right it's heavy. A 75' 100 amp cable made by Hubbell Marine weighs 113 lbs and retails for over $4,000. Wire size is 2 gauge.
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Old 09-29-2013, 05:33 PM   #16
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Your right it's heavy. A 75' 100 amp cable made by Hubbell Marine weighs 113 lbs and retails for over $4,000. Wire size is 2 gauge.
Wow...sure most people put that on some kind of auto retract like a Glendenning Cablemaster...I sure would!

I was just talking a 50 amp cord and it's not really that bad to drag around...just bad tring to coil it up which I normally don't.

With the right CB panel it splits the 2 power legs into 2 - 50 amp busses...so in effect you get a 100 amps usable...I think you know that but just making it clear to those who don't.
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Old 09-30-2013, 05:52 AM   #17
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.>it has to turn something off that I don't necessarily want off at that moment.<

Many on board items like a HW heater have enough capacity that it or something like a reefer would never be known if it was off for a while.

Those that cruise will eventually end up at an old marina , that has 15A service.

Automatic load shedding easily allows almost a full power lifestyle.

With a following transfer inverter like a Trace 4024 about every thing , including the washing machine or dishwasher can be powered , and have the battset up to par for AM departure..
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Old 09-30-2013, 07:30 AM   #18
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Wow...sure most people put that on some kind of auto retract like a Glendenning Cablemaster...I sure would!

I was just talking a 50 amp cord and it's not really that bad to drag around...just bad tring to coil it up which I normally don't.

Yep, we just installed a Cablemaster. Got tired of moving, uncoiling, deploying, coiling, storing the 50' cable manually. Lifting the carpet, lifting the hatch, pulling out the cable, closing the hatch, replacing the carpet... Or sometimes carrying the cable down from the bridge... and we're not getting any younger.

So far, the Cablemaster is a big improvement... although of course it wasn't inexpensive.

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Old 09-30-2013, 07:43 AM   #19
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For my style crusing...I usually just leave the cords and hose faked out on deck...they get used enough that storing them is just a waste of energy and my side decks are wide enough. The single 50 amp cord will be less of a hassel for me than 2 - 30's I'm pretty sure.
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Old 09-30-2013, 08:27 AM   #20
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Bay Pelican was originally equipped with two 30 amp inlets with the load divided between the two. 15 years ago I had this changed to 50 amp 240 volts and haven't regretted it. Since then I have used every combination of adapters imaginable. At times I have used a single 30 amp cable with an adapter at the boat, as well as two 30 amp cables. I have had to use a 50 ft cord plus a 25 ft 50 amp cord. In the last couple of years I have used a modified 30 amp US cable to plug into a European 16 amp 240 volt plug (connected to an isolation transformer).

Basically the 50 amp, if done right, gives you all the possible options provided you acquire the adapters (not cheap).


If I were cruising in North American and planning on going to a number of marinas, I would buy the following adapters, two 30 amp smart Y to 50 amp, 30 amp to 50 amp, a 50 amp/100v to a 50 amp/240v , a 15 amp to 30 amp, a 50 ft 50 amp cord, a 25 ft 50 amp cord, and keep both 30 amp cords. I have used them all repeatedly.
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