ELECTRICAL

Well, what can I say on this subject? I've given this much thought and decided to handle it in the following manner. Obviously I cannot present wiring diagrams because no two vessels will be wired alike. Also, the wiring of any vessel, even rather small ones, can and usually does get a bit complicated. Therefore, I've decided to offer just 'tips & suggestions' which hopefully you can use as a guide to help you better understand the electrical requirements for any vessel. Perhaps then, you and maybe an 'electrical friend' can produce the proper result for your boat.

All sternwheel boats which have any 'live-aboard' facilities, require two types of voltage. One is DC or direct current and the other is AC or alternating current. The DC voltages you will be dealing with will be 12 volts or under. The AC voltages will be 110 volts and perhaps 220 volts.

SPECIAL NOTE: I strongly urge you to try and power as many of the necessities on your vessel as you can with 12 volt DC power . Leave only those items which must have AC for the AC circuits. Items such as the hot water tank, air-conditioner and outlets for appliances such as toasters, hair dryers, coffee pots and the like. Cooking can be safely done on a propane stove if the propane is properly installed and modern propane/110 volt refrigerators are quite good. This will greatly relieve your dependency on shore power and lessen the annoyance of a noisy generator set. Trust me on this one and you'll thank me for it some day!

Let's start by listing some of the 12 volt DC items you'll need to power. This list includes the most common items but, your vessel may have more or less.

The above items, with exception of the starting motors, receive their power from a 'bank' of batteries which I suggest you install somewhere in the engine room that allows easy access for checking and maintaining the water level. These batteries must be 'deep cycle' type. This means they are design to go from full charge to low charge and back without damage and supply power at a low amperage draw for long periods of time. Conversely, 'starting' batteries supply high amps for a short period and must be keep fully charged to prevent damage.

Two or three 12 volt deep cycle batteries are usually enough to handle the rest of the requirements. Personally, I prefer to use 6 volt deep cycle batteries with a pair wired in series to produce the needed 12 volts. This results in higher initial cost but I've gotten excellent battery life from this arrangement. In fact, I have one pair that is 16 years old and are still doing well. The output from these batteries should be routed through a 'selector switch' which allows you to select output from battery 1 or 2 or 3 or all. In addition, these switches have an 'off' position which shuts down all 12 volt DC power. I strongly suggest that when leaving the boat for any period of time, the batteries be shut off to prevent accidental discharge if something was inadvertently left on.

A starting battery or batteries which will supply sufficient amperage should be included for each engine used on the vessel. This usually is just the main engine and generator set and the starting batteries should be installed as close to the engine starters as possible.

Charging of the batteries is handled in two ways. First is the alternator on the main engine. This alternator should be of sufficient size to charge the starting battery, the accessory batteries and carry the 12 volt load of the vessel while it is in operation. Most often, a 100 amp alternator is sufficient. Most generator sets are capable of charging their own starting battery. Output from the alternator should run to a 'splitter' which divides the current flow. This splitter can be 2, 3 or 4 way. A 2 way allows for charging the starting battery and any of the accessory batteries that are turned on. A 3 way will allow charging of either of two accessory batteries whether they are turned on or not. A 4 way will do the same if three accessory batteries are used. A second means of charging is via an 'automatic' battery charger. This charger really only needs to have enough charging circuits for the number of accessory batteries being used. Whenever the vessel is powered with AC, this charger will charge any of the batteries needing it. I should point out that most of these chargers are 'tapering' and will supply a small amount of charge even though batteries are fully charged. Over extended periods of time, this will cause the batteries to dry and could ruin them. I suggest you don't leave the charger on when no one is around the vessel. After all, the batteries should be shut off so there is no drain therefore no charge is needed and the batteries wouldn't be boiled dry.

Any vessel should have at least two distribution panels for the 12 volt power. One should be in the engine room and the other in the Pilothouse........usually under the instrument console. These panels can be equipped with either fuses or breakers. The wire leading to these panels, especially the forward one, must be of sufficient size to carry the potential load plus minimize voltage drop. I can't tell you what size wire because I don't know how far that run is or the load you wish to draw from it. I can say that the wire will be in the number 4 or larger range for both the positive and negative runs. Yes, you read correctly. Do not use 'hull grounding'. Run twin leads to any device and the ground should be directly to the battery and not via the hull. When possible, use black for the grounding leads. Someday, maybe you can buy me a beer and I'll explain the reasons for direct battery grounding but, the explanation is beyond the scope of these writings.

While on the subject of wire, I must emphasize "use only stranded wire" to prevent possible breakage due to vibrations and flexing of the vessel. Most components can be connected with number 12 or 14. The only use for smaller wire might be for items like intercoms or some speaker leads. Items such as search lights might require a size 10 or even an 8. Conduit is not required however, I strongly urge you to purchase wire with an insulation designated THHN. It costs a bit more but it's well worth the safety it adds.

Okay, it's time to talk AC. First, you must determine if you need 220 volts or if you can get by with 110 volts. If you intend to use central air-condition, you'll need 220 or, even without central air, if you have enough 110 volt devices you'll need 220 volts. Keep in mind that 220 volts is obtained by running two 110 volt lines plus a neutral and/or ground. The two 110 volt leads can supply only 110 volts or they can be combined to produce the 220 volts.

Regardless of your power needs, you will need two basic components. One is a ship/shore selector switch and the other is a distribution panel which houses both the main breakers and the individual circuit breakers. I usually include one more item and that is a 'twist lock' receptacle located outside and on the forward area of the boat. This is for connecting the shore power cord to the vessel. This cord is always a three conductor, stranded wire and is usually designated SO cord. The size of the wire depends on the length of the cord and the amperage you wish to supply the vessel. Usually a number 6 wire is sufficient. The type and configuration of the receptacle and plugs for this cord is determined by both the voltage and amperage requirements.

ANOTHER SPECIAL NOTE: Some of you electrical types may say that for 220 volts, a four wire cord should be used with the forth wire grounded to the hull. I, and many others, respectfully disagree. We feel that the 'supposed extra protection' offered by the grounded hull is, at best, dubious and certainly does not offset the very real potential problem of stray currents. These stay currents being those at docks where receptacles are improperly wired or from vessels at those docks which have improper wiring of their own. Of course, these stray currents through a vessels hull while immersed in a conductive medium like river water is what causes electrolysis. Any further discussion of the matter will require one or more six packs of cold premium beer on a warm summer evening while sitting on the upper deck with a Patsy Cline CD playing.

If you follow my advice, you will need to run three number 6 stranded wires with THHN insulation from the forward receptacle to the ship/shore switch that I always mount in the engine room. This switch uses a spring-loaded, snap-action to connect or dis-connect all three leads from shore power or gen-set to the distribution panel. If you're running 220 volts, it breaks both the 110 leads and the neutral. If you are running only 110 volts, it breaks the 110 lead, the neutral and the ground lead. The distribution panel should be isolated from the hull also. This means that all grounding is done through the leads back to the shore based panels. If you are extracting 220 volts from your generator set and if it has a fourth or ground wire, do not connect that ground wire to the ground buss in the distribution panel or you have grounded the entire system to the hull. Instead, route only the two 110 leads and the neutral through the ship/shore switch. With this arrangement, the only time there is any grounding to the hull is when the generator is connected to the distribution panel and that should be when the generator is running and you are not at dock side. This greatly reduces if not eliminates the possibility of electrolysis.

Now, if you selected 220 volts for shore power, I suggest that you put all of the high priority circuits on one 110 volt leg. That would include items like a hot water tank, interior lights and maybe the refrigerator and battery charger. With this arrangement, if you dock where only 110 volt power is available, a simple adapter on the shore power cord will allow you to power only that side of the distribution panel and you can power the necessities.

You've probably noticed by now that I have referred to both 12 volt and 110 volt interior lights. I suggest that you install both. If you dock where you have shore power, use the 110 lights. If not, use the 12 volt and you don't have to listen to a gen-set running just to make a mid-night snack or find your way to the head.

All 110 volt circuits should be wired with number 12, three wire stranded cable with THHN insulation. This arrangement will also allow the use of Ground Fault Interrupter outlets in the kitchen and head if you wish to use them.

DO NOT route any wires in the hull unless you absolutely have to! Items such as the fresh water pump may require leads in the hull. However, any wires in the hull should be tight against the underside of the deck or, if they must pass through a bulkhead, they should do so via a 'packing gland' just like any other bulkhead penetrations.

I realize this is quite brief for such a complex topic. However, as always, if you have questions, please get in touch with me.

 

 

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