I am in the process of figuring out the purpose of every wire and cable on my boat
and to get me going I asked for the wiring
diagram from the yard which built my boat
I just received it and came to the conclusion that I am missing some key design considerations which I thought were worth sharing. Both for those looking to (re)build their own system and for those looking to add modifications (as I am doing/have done).
1. Cable numbering and size. Having a schematic (my simple system is 25 pages worth) will greatly simplify troubleshooting since each cable can be identified via their number. So... make sure any cables
added are also numbered properly and added to the schematic. Indicated cable size also helps selecting new/replacement cable sizes based on what the yard would have done.
2. All fuse sizes properly recorded.
3. There are four 12V dc 'groups'. The first drives the switching panel and all low consumption appliances
connected to it (lights, instruments
, etc); The second is not routed via the switching panel and is controlled via relays (which are themselves controlled by the switching panel) and powers higher consumers such as the autopilot
and the fridge; The third group does route
via the switching panel but is connected directly
to the battery
(as opposed to via the master switch and has its own dedicated fuse) and powers the VHF
, gas switch and bilge pump
(so hopefully these will continue to operated until 'the end' regardless of failures elsewhere); And the fourth group I guess is not really a group but this is the heavy gauge cabling going directly from battery
to consumers such as winches, windlass
Given what I have learned so far (being most impressed by the thinking behind the VHF/bilge pump
set up) I would never simply rip out any wiring
from a boat (eg a project
boat, not that this would ever be my thing) and anyone looking to do work
on the electrical system
is well served sourcing or putting together themselves a schematic.