Electrical




	Best price on SPade Anchors!


	The basic tools I use most.


	My must have boat building book list.


Having built a house and wired my shop and boat shed my selfI have a fair amount of experience with domestic electrical systems but boats are different. First of all it has to be self sustaining, generating its own power. Second, it has to service in an environment that is naturally hostile to electrical systems. Finaly it is not one system but as many as six systems that have to work together and yet remain isolated from each other. Rutu has three different power systems, two 120V and one 12V, and three grounding systems, 12V, Lightning and SSB. You may have noticed I didn't mention a galvanic grounding system. We'll talk about that later. .

		The 120 V AC System

	One 120V system powers only the air conditioners. The other supplies the water heater, the ProSine 2000 inverter/charger and the house curcuits. If only one shore power service is available, the Blue sea 8086 panel allows the two 120 V systems to be bridged together but use of the house curcuits will berestricted while the A/C is running The diagram at left shows two panels. This was desighed before I found the Blue Sea 8086 which has most of the curcuitry including the bridge built in.. The biggest power conusmer on Rutu will be the air conditioners. Being a born and bred Southerner, I am pretty warm natured and can get along without A/C but it does get warm at the slip in the Summer and if I ever expect marilyn and Ruth to even come aboard, air conditioning is a must. Rutu will have two reverse cycle Mermaid marine units. A 16,000 BTU unit under the settee will cool and heat the forward stateroom and the main saloon. A 12,000 BTU system serves the aft cabins. Together with the cooling water pump they will need about 25 amps. While it was possible to wire the boat with a single 50 amp shore power system, two 30 amp systems would provide more flexability. Logically, one of the 30 amp systems will serve the A/C exclusively. The other 120 V system is a bit more complicated. . The second, actually primary, 120V system feeds through a ProSine 2000 watt inverter charger and powers the galley apliances, main computer and stateroom outlets. One thing is essential in a curcuit served by an inverter. Absolutely no other source of AC power can serve that curcuit. . The Blue Sea 8086 panel has a lock out system that prevents combining the two curcuits unless one of the shore power inputs is disabled. My responsibility is to make sure there is no other way for the two systems to meet

The 12V DC System

This diagram is the 12V system. It will be fairly straight forward except that each cabin will have a separate distribution buss and I have a special one for exterior lights.

There are cirtain minor conveniences that make life easier on a boat. I happen to really like the second dog watch and the morning watch. Mainly because sun set and sunrise are my favorite times. The only reason I want to go below is to get more coffee. Therefore, I want all the nav, spreader and cockpit lights controlled from the helm. Blue Sea makes a six position waterproof panel that is perfect for this.

I am a little nervous about running all that power close to the main compass so I am locating the deck light sub panel in the traveler arch along with the engine instrument panel and the sterio speakers.

The Charging system

I have to confess to being a gadget freak when it comes to electronics. I am also one who does not subscribe to the minimalist cruising philosophy of Lynn and Larry Pardee. I like my creature comforts. So Rutu needs a lot of power. That is not as simple as just adding batteries.

In a properly designed electrical system, the charging equipment has to match the battery banks. As I will be using 4 Trojan L-16HC floor polisher batteries totaling over 800 amp hours, Rutu's charging system has to have a pretty healthy alternator. Combined with a ProSine 2500 inverter/charger and a pair of Siemens solar panels mounted over the aft bimini, the batteries should stay happily full.

To monitor the whole thing I picked up a Link 10 on Ebay for a bargain price.

Wiring it all up

I am a pretty fair shore-based electrician. I wired my house, the wood shop and the boat shed and after a real electrician genuflected over them, the city inspector blessed everything but this is the most intimidating job I have ever tackled. While the laws of electricity don't change everything about the wiring is different. Wire sizes and types are much more critical, connections require crimped terminals rather than wire nuts, routing is a real challange and making sure the various systems remain isolated in that mass of wires can get mind boggling. My faithfull electrician looked at it, shook his head and said "You are on your own!"

I decided on a back panel for terminating all the wiring. THis will add a couple of connectors to teach curcuit but will greatly simplify the installation and maintenance.

What size wire?

Remember that couple of days back in highschool science when the teacher covered volts, amps resistance and such? Well, I still have trouble remembering if the A goes over the R or which side the V is on. On top of that, you have to worry about things like ohms per foot and circular mils and a bunch of other things. The first tool that needs to be aquired takes care of all that and best of all, it is actually FREE! Wiresizer 2.0 is a freeware program that is available for downloaded from Alden Trull at www.midcoast.com/~aft. Tell this little VB3 program the voltage, amps and distance and it will tell you which wire size to use, what the voltage drop will be, what the maximum current the wire can carry is and even save the data to a file and total up how much wire you need of each size! Wiresizer 2.0 has saved me uncountable hours figuring out how to make up runs.

The Tools

Besides the normal pliers, wire cutters, screwdrivers and such a high quality ratchiting double crimp tool and an automatic wire stripper are absolutely essential. Do not waste money on the cheap crimper/strippers at Radio Shack or the hardware store. There are litterally hundreds of terminals to be made up and marine ring terminals cost upwards of $.25 each. The cost of all the terminals that a cheap crimper will ruin far exceeds the cost of a good ratcheting crimper. A good automatic wire stripper, the kind that grabs the wire, cuts the insulation and pulls it off makes the job much faster and saves a lot of dental bills when you really get frustrated with the cheap ones.

The heavier wire requires one of those hammer type crimping tools. The one with the lever on top that holds the terminal while you hammer it down works great. There is one mystery that I have not solved yet. The racheting crimper fits up #10 wire and the hammer type fits down to #6. I don't know what do you do about crimping #8 wire and I have a lot of it to run!

If I were going to make this my profession I might invest in a special cable cutter for the 1/0 and 2/0 battery cable but I am only going to make 15 or 20 cuts in my lifetime. I have found that a regular pair of compound pruning shears makes a nice clean, square cut.


	[Home] [The Design] [Building The Hull] [Casting The Keel] [Bulkheads & Interior] [The Deck] [Systems] [Electrical] [Plumbing] [Refrigeration] [Fuel System] [Steering] [Special tools] [About Me]


	Site last modified:04/12/04