Electrical System: Safety Consideration

[HeinSdL]

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, etc.

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.

[goboatingnow]

I’m redoing the panel on my Bavaria 36

Im adding a digital fuse system and digital switching of my own design using laser cut back illuminated panels etc

I agree with you

(A) identify all cables.

(B) remove redundant wiring

(C) like you I have
1. dc fused ( electronic fuses ) , battery isolated

2.dc fused ( electronic fuses ) permanent battery connection.

3. Dc high current ( >30A) mechanical fused ( with blown detection )

In my case I am recovering significant panel space at the chart table by placing the remote breakers behind the panel and the electronics allow be to combine functions ( ie switch all the correct nav lights with one button )

[er9]

Originally Posted by HeinSdL

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.

i would agree until you get to a point of knowledge where it all makes sense and you then have intimate knowledge of DC/AC systems and specifically your own system aboard our own boats. I fantasize frequently now about ripping out every single 40 year old wire aboard and starting from scratch. unfortunately i live aboard part time and need systems to work so i cant indulge my fantasy but the day is coming...

that being said, to new boat owners with lack of specific knowledge, i wouldnt recommend touching a thing until you are dead certain you know what your doing. i think making schematics is a natural evolution in the learning process. you get to a point of knowing and then a schematic becomes a requirement to move forward with upgrades or just general preparedness.

for a serious boat owner though, i think learning the electrical side is important. having schematics does not help much for most older boats as the systems most likely have been tinkered with by previous owners, maybe extensively and most of us can no longer get original wiring diagrams. the only guarantee of their accuracy if your lucky enough to get one, is knowing what your looking at.

[goboatingnow]

If you don’t have a schematic then I would reccomend building one from scratch or at very least a cable identification marking system. And a termination point list ( spreadsheet )

[AlexCollier]

...and do not forget those pesky little bits of line found in marine harnesses - called "Messenger lines".
These are carefully left so that new lines can be pulled through the same path.
If you do use one of these I recommend including another line on the wire pulled so the used one is replaced.

If you are running a new wire then ensure a messenger line is included with the pull.

[Cadence]

Originally Posted by HeinSdL

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, etc.

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.

As you trace the wiring out, put labels on each end so you don't have to ring or guess in the future.