Rewiring a boat - what is involved?

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CharlesM

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Hello All

I would like to COMPLETELY rewire my 43' ferro cement boat. As with all other jobs, my initial thoughts are 'It can't be all that difficult'. I am wondering how nieve (can anyone spell that?) am I being?

In order to plan my budget, what can I expect something like that to cost, or perhaps more accurately, how long (hours) would it take a professional to do.

I understand this is a bit like how long is a piece of string, but indicators would be appreciated.

I don't think The job will be done this year - will have to leave for next year but would like to get some ideas.

Cheers
Charles
 
Not really feasibl;e to give any type of estimate on this as it depends on

How much equipment you need to wire in,
How many spare cables will be run,
Whether you are replacing fuse system for a new breaker gizmo,
How accessible the existing wiring loom is, or if creating entirely new conduits, how easy to install new conduits.

This would be difficult to estimate for a known AWB, let alone a MAB

Try and estimate for yourself and then quadruple the estimate.
 
I would break it down into smaller tasks. I have mostly rewired my own boat, but I suspect it is not on the same scale as yours, and I've still not finished yet. I did find out how amazingly easy it is to wire up things wrongly, even when there are only two wires involved (i.e lights). Unless you've a burning reason to get the whole thing done now (no pun intended), you can then do it in stages, employing a professional when you chicken out or run out of time.

0) First, how are you going to organise fusing, switch panel(s) and charging. Especially if you're changing anything.
1) Interior and nav. lights are the easiest, and you can estimate the cost just by the length of wire involved.
2) I treat replacing the mast wiring as a seperate task, but for lights it is as above.
3) Instruments: I suspect you may not be thinking of doing all these, but log, radar, gps et. al. all come with their own cables which you will have to order form the manufacturer. VHF is easier.
4) Engine. New wiring loom? Plus the multiway wire and plug from the switch panel.
5) "Power" i.e. larger items such as pumps, winches, windlass will need large size cable. As will the main starter and alternator cable from the engine.
6) Mains cabling. More variations than you can shake a stick at, so generalisations are useless or book-length, but planning is probably the hardest part .
7) Everything else!
 
Naive is the right way, I think. Be aware that it is a major job, but worth doing in the long run. I set out to renew some bits of wiring and add some electronic bits to our 1988 Westerly and in the end ripped almost all the exisiting wiring and switchgear and started again. I had neither the courage nor the knowledge to tackle it on my own and brought in expert help. The big problem with older boats is that the wiring systems are generally derived from the motor industry and not designed for marine use. You also find, as I did, that some of the add-ons are badly done, if not dangerous. At least if you've re-done the whole thing with superior materials, better suited to modern electronics etc, you should have a more reliable and, most importantly, safer arrangement. On the books front, I found James Hortop's illustrated guide to boat electrics very helpful even to a Klutz like me. Good luck!
 
I re-engined my last boat (twin-engined mobo). This was far from straight-forward as it involved building the engine bearers up, finding a route for the two new very large exhausts etc etc. Then I decided the whole boat needed rewiring. All I will say is that the rewiring job took more than twice as long as all the engine work put together. I didn't attempt any 'up-front' quantity surveying. just bought what I needed as the work progressed. Except red and black cabling, which was far cheaper if bought on huge drums
 
So how long did it take you people to rewire your boats - in hours if an estimate is possible?

I guess it would be best done by myself with assistance from professionals where possible.

Can it be done in a week full time, 2 weeks, a month etc?

Cheers
Charles
 
I rewired my 34 footer from batteries right through. You will need guidance, either from a professional, or from one of the many marine books dedicated to the subject. I guess it took me about 10 working days over a winter to do it. The biggest challenge is making it all fit, and all look neat. This is important for trouble shooting later, and adding extra kit.

Go for full magnetic (not thermal) breakers, and make sure your wiring is at least the recommended minimum. Don't skimp. Get your self some proper tools for it, too.

I probably spent close to a grand on all the bits.
 
I wired my boat from scratch. I'd say it was about 3 weeks work. To give an idea of the level of complexity, I have a total of 28 MCBs.
 
I rewired my boat last year with a full system which I bought at the beginning including batteries charger and the cable and connectors that I THOUGHT THAT I WOULD NEED. Even though I had some knowledge starting out I learned a lot while doing it.

If I were to do it again I would approach it this way.

1.List the individual items that you intend to connect. 2. plan and put in place a fish wire for the supply to each, right back to the proposed position for the main board. Then using the length of each run and the expected load calculate the size of wire that you need, and the amount needed.

Buy only best quality marine grade cable. Buy the proper size crimp on connectors etc, make sure that these are marine quality. Get a professional quality wire stripper and crimping tool, and a multi meter.

There is some colour code for the cabling and I would use this rather than just red and black.

It really is not that difficult if you breakdown the stages, Planning the cable runs and positioning the batteries the chargers and the board will make it much better, easier and neatness will pay off in the long and short term.

I think it probably took me a week fulltime. I spent about £1,100. but it was well worth it.
 
Suggest a book .....

Alastair Garrods - Electrics Afloat.

(A PBO associated book) ISBN 0-7136-6149-6

Viewed on www.adlardcoles.co.uk

Available in near all chandlers ...

Believe me - I've looked through most and this is the simplest, easiest to understand book of the lot with good illustrations and also a pull out schematic of a total boats wiring etc. Yes there are other books that will expand on various aspects - but when contemplating such an exercise - this is a good place to start.

I have no connection with Book, Author etc. other than a happy owner of a copy ex Hamble Book Shop.
 
Wiring size guide here....

Wiring guide


You may want to break the job into manageable chunks, so make an assessment of what is currently in place and investigate the routing which makes sense if you are starting again.
 
Pandos and pyrojames could have been describing my experience exactly: 35' boat, complete rewire (except for mast), all work by me including the main board.

About £1k for the stuff and a few weeks off and on. I was living aboard, so keeping some power to the old system while installing alongside wasn't easy.

Tinned cable throughout, breakers rather than fuses where I could, wiring in conduit where possible. Wherever I thought that one day I may decide to have eg a light "just there", I ran a cable through before rebuilding over it, tucking the ends out of sight.

VALUABLE TIP - when the wiring runs were exposed, I took digi pics so I will have no excuse if I put a screw through a wire in the future!
 
I have mostly done my boat, with a team of me (apparently knows what he is doing) and SWMBO who as an electrician makes a good coffee. But, this is not such a bad thing as it means she will follow instruction and does in fact make a good labourer.

I think, given a schematic diagram and all materials to hand I could wire my boat in a week as a two man team. A lot of time for us is crossing cables from hull to hull, oh how sometimes I would love a mono!

But it never works like that, you will not have all the gear to hand, you will be learning as you go, dismantling cupboards to get at the old loom, etc etc.

As a diy job, a month to get the back bone of a new system in place.
 
As others have said, this is not a job to be taken lightly.

I completely re-wired my boat(28'er) last season and it was a lot more difficult than I expected, and a lot more expensive. I think mine probably cost about £600, but maybe more, adiing up all the bits and bobs is quite hard to keep track of. I had to buy a charger, alternator regulator and all the components for shore power which I didn't have before which was about half the cost.

My tips would be:

Break it down into 2 stages: starting/charging system and domestic system.

Research research research. I am reasonably competent with electricity and it's physics, but there is so much involved in boat electrics that you can spend infinite hours reading up on it. Also, opinions differ so you need to vary your sources to get the real picture. I used 'The Marine Electrical and Electronics Bible' by John C. Payne as my main reference, backed by a couple of other books (including Calder), and the internet (especially these forums) is full of invaluable advice.

Work out exactly what you need. This is where I went wrong. I have been back and forth to the chandlers, ordered stuff online and generally made the whole process take much longer than it needed to by getting bits as I went along. Wire, grommets, breakers, terminals, switches, panels, fixings, this, that. Work it all out first so you can get on with the job rather than having to stop and go and get new parts all the time.

Get the right tools for the job. Proper ratchet crimpers are a must for the small crimps, and you need to work out how you'll put the ends on the battery cables, drill the correct size wholes for the grommets etc etc.

If you do the research, plan it well, have all the parts/tools and have a free week then I dont think you'll have a problem.

Good luck.
 
I spent about a month (on and off) planning the work then perhaps another month practically full-time doing it. Its amazing how long even a simple operation like, say, fixing a cable support can take if your on your head or stuck half-way into a small locker. As for buying all the bits up front, forget it. Order the big bits, obviously but there will still be bits you forgot or didn't realise you would need. And the chandlers is NOT the place to buy unless money is no object. Specialist marine electrical supplier or your local electrical wholesaler should be able to come up what you need.
 
I was impressed by the recommendation and the description of contents of 'Electrics Afloat' so I bought one.
Thanks
 
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