This is what I did. Whether or not it makes any sense to you is something else.
First, I went around to every piece of
equipment on the vessel wired to anything, and labelled it and the voltage and current draw under full load required for everything. I marked the position of all of this stuff on a drawn up plan of the vessel.
Then I drew in red pencil all of the current draws in excess of or up to 100 amps but exceeding 15 amps. That was the
anchor windlass and the
cables for sail and
dinghy handling--even though most would not draw more than fifty amps except for the
anchor windlass. On the plan I drew this wire as heavy tinned cable--and that would run from the anchor windlass to a pony battery (a large one) situated abaft of the chain locker in a sealed water-resistant fibreglass box with a lid that was easily removed, but strong enough to have some light
equipment stowed above it as needed on a temporary basis. Into this heavy cable I placed a 100 ampere overload switch. It is better to have that inconvenience of re-setting the switch than replacing a burned out anchor windlass
motor, if the anchor is jammed. For the other loads, fit overloads as required. If the expected draw is 30 amps max, fit a 40 or 50 amp overload. If your
budget does not run to overloads--use ceramic cartridge
fuses and carry spares.
All of the heavy amperage
cables are tinned copper cables ex-aircraft quality and acquired from military surplus. If you can not get access to this sort of cable second hand--welding cable for welder's 200 amp leads is good enough.
Almost every other load on the vessel is less than fifteen amps, except for the charging current to the pony battery. Because I run the anchor windlass only with the
engine running, and gain another fifty possible amps from the
alternator, I also run the heavy cable from the engine start battery to the pony battery. This way I bypass the
regulator system for the main house battery bank, and just deliver as much as the
alternator can put out to augment the pony battery. After hoisting the anchor, I usually run the
diesel for a half hour or so afterwards as I motor out of the anchorage and set sail when the
wind rises. The pony batrtery is also charged by the
solar array and house battery system, but I fit a blocking diode, so thet using the windlass does not draw down on the house batteries or burn out the charging 6mm tinned twin charging lead from the
solar array and house batteries charger--which is also a mains powered
charger for use in a marina as well as being able to be connected to a gen-set if required to be..
The problem now becomes a lot simpler. You will need a roll of 6 mm tinned DC twin cable. You will also need a few lengths of open-able square conduit, some round conduit (all PVC) with angles and
inspection ports on some of the angles and a couple of packets of countersunk
stainless steel posi-drive screws. I know some people think
stainless steel staples are adequate. I am not among them.
Next you will need some cartridge
fuses, ten, fifteen and some even larger. Automotive fuses can
work here if you can keep them in a dry
environment.
From here there are two schools of thought. One
school uses two bus-bars, and an earth heavy cable but one kept separate, which also runs the length of the vessel. The bus bars carry the main supply of all DC to all equipment, lights, gas detector etc. Moire on the earth later
The individual equipment is locally switched, (or permanently wired ON via a removable fuse). Equipment is locally fused, and the large and complex switchboards and excess metres of duplicated wires to and from
remote switches are not used--just a few small circuit switches for nearby equipment, the master charging regulators for the house battery and all of the isolator switches for the bilge-pump float switch over-ride switches, as well as any meters that one may feel are required for monitoring equipment or the main bus-bars or house batteries.
The earth cable links everything metal on the vessel EXCEPT for the
radio and
Radar equipment which has a separate earth plate outside the
hull. The other earth system is part of the
lightning protection and is NOT connected to the negative rail of anything. On a boat, everything must have two wires and a fuse, preferable a flame-proof fuse. The earth linking cable just links anything metal and conductive and connects it to an external
lighting earth--but NOT
electronics equipment which has its own entirely separate earth plate.
Then there is the
school that wants everything double-switched, one at the equipment, the other at a master panel. Lotsa luck--you wire everything in the same way except there are few if any local fuses--and all fuses are set into the long and wire-consuming positive legs of the DC supply in the panel itself, and they are usually those crappy glass fuses set into a spring loaded socket. Their only advantage is speed and ease of replacement, and they are no better than a plug-in automotive fuse--and may in fact be inferior.
I run all of my wires in conduits, waterproof ones set through watertight bulkheads using
epoxy bog, or the re-enterable square ones with two channels for the bus bars, and smaller square re-enterable ones for the take-off's to individual equipment. When one takes off a wire from a bus bar, strip some
insulation, take two turns of 6 mm
core tinned around the wire and solder. To the other end of this wire where it reaches youyr equipment, fit a cartridge sealed fuse. The only exception is in the bilges. Always fuse any circuits to
bilge pumps well clear of the
bilge itself--just in case there are any fumes present and the gas detector has not picked them up. ALL
BILGE PUMP CONNECTIONS MUST BE SOLDERED. Cover the soldered joints with heat shrink tubing, and ideally, the
bilge pump wiring should be in circular conduits specifically for the purpose. A trough-hull and some non-tocic PVC hols wioll do to get the wires out of the bilge as tidily as possible, and from there the square conduit can take the wires to the bus bar or master switch panel. Small re-enterable conduits can hold about two or three circuits--but they seldom hold more than two. Larger re-enterable conduits can hold a whole bunch of circuits very neatly, and if one has labelled the cables as one inserted them, it is easy to isolate them later for further testing or additions.
Bilge ventilation is another topic.