The installation in not done until…

[SailingHarmonie]

For everybody, especially people new to boats and not mechanically sophisticated, an installation of new equipment is not complete (and should not be paid in full) until a wiring diagram AS BUILT is delivered. In the best case on a complex job that delivery of the drawing would be in person, on the boat, and include a walk-through and explanation of the major parts at whatever level of detail the customer can understand.

Any decent mechanic/electrician would include that as part of his quote up front. Anyone not offering that would immediately be suspicious to me.

Especially on a complex project, I am always working from a drawing that I mark up as I go. My brain is not big enough to hold the details of multiple projects on multiple boats. At the end of the installation it is not a big deal to clean up that drawing and deliver it to the customer.

As part of the vetting of anyone doing any level of wiring work, you should ask to see a sample of the kind of wiring diagram that was delivered on a similar job.

Of course this is not free. It will cost hours of the tradesman’s time. It could easily be 15% of the total cost of the job. It is absolutely, 100%, totally and completely worth it.

In fact, if you are buying used a boat, and have no wiring diagram, getting one should be a priority. If you can do it yourself that’s great. If you have to hire someone to do it for you, it will be worth it the first time something breaks.

If you are buying a new boat, and it does not come with a wiring diagram, all I have to say is, wtf?

[Kettlewell]

Sure, I have bought used boats with wiring diagrams that are always out-of-date and just plain wrong. No way of knowing until you've used the boat awhile and learned things. Even on new boats they are often just wrong. Most sailboats are built in such low quantities that each one is essentially semi-custom. OTOH, I would never pay anyone to install any equipment, so I tend to know how it was installed. Plan on spending a year or two, at least, to get to know any used boat, and then plan on redoing lots of wiring.