Re-wiring my boat

[manxmike]

My boat is now about 28 years old, as is the wiring loom. When I say wiring loom I really mean a knitted collection of mainly brown wires, very few (if any) of which are wired through the fuse panel.

 

To me this state of affairs is not ideal and obviously needs replacing.

 

However - I really don't want to strip out the interior cladding and paneling to get at the old loom.

 

Has anyone rewired whilst disconnecting and leaving in place the old loom?

 

I anticipate using plastic trunking tucked up under the "step-back" with spurs going to whatever items need power.

[by'eck]

Nothing wrong in leaving the old wiring in if you can ensure its completely disconnected. Any visible loose ends may cause confusion to yourself or a future owner though so best remove them.

 

Fitting new wiring in rectangular plastic ducting under the gunwhale is an excellent idea. Suggest using cable ties at regular intervals to hold it in before fitting ducting cover.

[BargeeSpud]

Another thought, are the edges of your ceiling finished like the pic below or is your superstructure T & G all over?

 

If it is, these panels can be a great place to run cables for ceiling lights etc.

A very useful tool to have is a cable puller like this one from Vehicle Wiring Products which can help you to run cables behind existing paneling. As with most things like this, try to draw out & plan your cable runs for each circuit, this will help you decide where to run your cables & to work out how much of each cable you need to buy.

Good luck & most of all, have fun!

[FORTUNATA]

My boat is now about 28 years old, as is the wiring loom. When I say wiring loom I really mean a knitted collection of mainly brown wires, very few (if any) of which are wired through the fuse panel.

 

To me this state of affairs is not ideal and obviously needs replacing.

 

However - I really don't want to strip out the interior cladding and paneling to get at the old loom.

 

Has anyone rewired whilst disconnecting and leaving in place the old loom?

 

I anticipate using plastic trunking tucked up under the "step-back" with spurs going to whatever items need power.

I once found out that fires on board boats (yachts I think) had a very high percentage connected to electrics. There's always been a conception that D.C. is safe due to the low voltage but we know differently. Whoever wired up your boat decades ago, as you say, didn't fuse all the circuits. So, your job is to consider:

 

Engine and alternator wiring. Are the battery terminals clean and well-connected. Do you have the correct gauge wiring to your panels? Are the voltmeters and ammeters fused (if fitted)?

 

There's no harm in over-rating D.C. cables and wires a bit where your lights and pumps and so forth are concerned. If you have the usual one pole engine ground wiring configuration (all negatives to hull) you only need to fuse each + supply cable accordingly.

 

One good idea always bounced about is to sum up the entire watts to be used on-board. For example, I seem to recall that water pumps weren't so far off 50 watts (that's if my memory serves me correctly). If so that would be about 4 amps flowing through the cable. I know that these days you can buy equipment far less power hungry but I still have ceiling lights at 20 watts (came with the boat).

 

Sure, it seems a good idea to simply bypass your old wiring and run the new stuff in trunking. You could be clever and use a cheap DMM to measure the old cables end to end if you can get at them and see how the Ohms resistance runs. Likewise to check for any leaks to the hull from damaged insulation you can't see.

 

I've never considered D.C. electrics at all easy. In some ways I find A.C. safer due to the much smaller currents involved.

 

Good luck with the rewire.,

 

 

 

 

[DHutch]

... never consider D.C. electrics at all easy. In some ways I find A.C. safer due to the much smaller currents involved....

 

Indeed so. The age alone is not an issue, our boat is 25yo and the wiring as it was when new, however goof wiring appropriate cable selection and fusing is essential in preventing issues such as boat fires.

 

I dont know what your experience/qualifications are but it might be worth spending some time learning about techniques for good wiring.

- Logic as to what runs where and feeds what.

- Cable and fuse sizing,

- The correct tool to make good crimp joints.

 

etc

 

 

Daniel

[tove]

Just wanted to concur with the above post. Electrical cabling is surprisingly expensive and scrimping on cable size is one of the most common mistakes on home fit-outs and is potentially dangerous. I also discovered whilst I was wiring out my boat that some appliance manufacturers will refuse to honour the guarantee unless a minimum cable size is used so if you're running a fridge etc you might want to check that.

Also think the above suggestion about using a cable puller an excellent one. It probably sounds like a huge faff but in the long run will give you a much more professional look than running cables 'over-land'. Just something you may want to bear in mind if you intend to sell the boat at some point in the future.

[WotEver]

If you want to replace a particular cable run with a new cable you can sometimes use the old cable as a draw string to pull the new cable (or bunch of cables) into place. It all depends if the original cable has been clipped in place and how many obstacles it negotiates.

 

Tony

[Ray T]

When we had the 240v mains cables replaced in CF the electrician pulled in a spare draw string at the same time should we wish to do any further wiring.

 

Worth a thought?

[steve7a3]

Age of the boat isn't always a catalyst for wanting or needing to rewire a boat either. My boat is only 12 years old but the wiring is, at best, a birds nest and none of it labelled. Nor do I have a wiring diagram. There are cables that end suddenly in one of the wardrobes in the forward cabin and cables behind the panel that seem to go nowhere, in some cases attached to switches that clearly do nothing. Luckily I've done a lot of electrical work before so have more than a passing understanding (and respect!) for both AC and DC and know which way up to hold a multimeter so the job isn't too daunting for me. More a matter of time and cost.

I too am planning on using trunking under the "step-back" as it will be hidden but still more easily accessible than having it behind panelling or timber strips. Unfortunately (or fortunately depending on your point of view) the lighting is all flush mounted LED downlight which means the wiring for them is all concealed within the ceiling. I'm hoping I can trace them back to the mess of wires running along the gunwale otherwise they will be impossible to access until I'm ready to re-skin the inside of the boat.