Why Most New-To-Us Boat Electrical Systems Must Be Rebuilt

This setup in our J/109, as she came to us, is actually better than many—at least the cables are correctly, in fact a bit over, sized—but it still needs a complete makeover. How many violations of ABYC recommendations can you spot? Leave a comment. Photo kindness of the surveyor.

Our new-to-us J/109, like most production boats, came to us with an electrical system, installed in 2004, that is not even close to ABYC compliant. Said system also had some dangerous defects.

And on top of that, the system as installed by the builders, while adequate for the light usage they envisioned, is horribly inefficient, and will be very frustrating, not to speak of environmentally destructive, to live with once away from shore power for more than a few hours—think running the engine for hours, and often, to charge the batteries.

The same applied to our previous boat, a McCurdy and Rhodes 56 that we owned and mostly lived aboard for 30 years, and the one before that, a Fastnet 45.

The Way It Is

But here's the thing, our experience is the norm, not an aberration, and the older the boat we buy is, the worse the system will be, so there's no point in wasting time pissing and moaning, rather, we need to fix it.

Two Tips For Buyers

But before we get into that, two tips for those of us buying a secondhand boat, as we did:

  • The boat will almost certainly require significant rewiring and electrical upgrades, so we better budget time and money to do that.
  • The survey will probably not warn us of this impending expense and hassle, so even with a clean survey we need to leave money in the budget for this project.

A Survey Won't Save Us

On the second point. Yes, I know, most surveyors claim to be ABYC trained and claim they survey to that standard. And maybe some do.

But the fact is that, during the process of buying our J/109, I read through three surveys on the class—two on the boat we bought, and one on another boat—and not one even pointed out that the batteries were not fused, a fundamental code violation and a potential boat-burner.

I also read through several other surveys on other types of boats, and not one had more than one or two trivial mentions of ABYC-compliance violations, and all completely missed problems and omissions that I could see at a glance in photos, like the one at the top of this article.

A North American Problem?

I'm guessing, but do not know, that the situation in Europe, and probably Australia and New Zealand, will be better, at least for boats built comparatively recently, both because in those countries regulations are backed up by the rule of law, rather than just being recommendations as ABYC's are, and because it seems that surveyors in these countries are, as a rule, more thorough.

But even so, our experience and what we are doing about it will still be of use to those of you in countries other than North America who are buying boats that are over about 10-years old, or boats that have suffered from electrical system modifications from a series of owners equipped with a lot more enthusiasm than knowledge.

So what the heck are we supposed to do about this state of affairs?


What about hiring a boatyard to fix the problems and upgrade the system to ABYC? Generally a bad idea for three reasons:

  • Most boatyard staff are woefully ignorant of basic electrical theory and the applicable standards; yes, including the ones that are ABYC certified—the courses they take are a joke.
  • Even if the yard has a person who does understand ABYC or CE, the likelihood is that they will have absolutely no idea how to make the system more efficient for cruising away from shore power.
  • High cost. More on that in a minute.

How bad are the first two issues? Really, really bad. For example, I know of only one guy here in Nova Scotia and one in Maine who I would trust to rewire my boat to be both compliant and efficient.

Gotta Take Responsibility

Given the deplorable state of training and knowledge among most boatyard "professionals" and even boatbuilders, particularly in North America, even if we can afford to delegate the actual work, we owners have to get at least a basic understanding so that we can check it's being done right.

The other problem is that even if you can find someone competent (look for independent contractors, not boatyards), you will probably have to wait ages before they can help you. The good people are invariably snowed under.

Don't believe it's that bad? Well, read on for a couple of examples:

  1. Why Most New-To-Us Boat Electrical Systems Must Be Rebuilt
  2. One Simple Law That Makes Electrical Systems Easy to Understand
  3. How Batteries Charge (Multiple Charging Sources Too)
  4. 5 Safety Tips For Working on Boat DC Electrical Systems
  5. 7 Checks To Stop Our DC Electrical System From Burning Our Boat
  6. Cruising Boat Electrical System Design, Part 1—Loads and Conservation
  7. Cruising Boat Electrical System Design, Part 2—Thinking About Systems
  8. Cruising Boat Electrical System Design, Part 3—Specifying Optimal Battery Bank Size
  9. The Danger of Voltage Drops From High Current (Amp) Loads
  10. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 1
  11. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 2
  12. Battery Bank Separation and Cross-Charging Best Practices
  13. Choosing & Installing Battery Switches
  14. Cross-Bank Battery Charging—Splitters and Relays
  15. Cross-Bank Battery Charging—DC/DC Chargers
  16. 10 Tips To Install An Alternator
  17. Stupid Alternator Regulators Get Smarter…Finally
  18. WakeSpeed WS500—Best Alternator Regulator for Lead Acid¹ and Lithium Batteries
  19. Smart Chargers Are Not That Smart
  20. Do You Need A Generator?
  21. Efficient Generator-Based Electrical Systems For Yachts
  22. Battery Bank Size and Generator Run Time, A Case Study
  23. Battery Options, Part 1—Lithium
  24. Battery Options, Part 2—Lead Acid
  25. Why Lithium Battery Load Dumps Matter
  26. 8 Tips To Prevent Lithium Battery Load Dumps
  27. Building a Seamanlike Lithium Battery System
  28. Lithium Ion Batteries Explained
  29. 11 Steps To Better Lead Acid Battery Life
  30. How Hard Can We Charge Our Lead-Acid Batteries?
  31. How Lead Acid Batteries Get Wrecked and What To Do About It
  32. Equalizing Batteries, The Reality
  33. Renewable Power
  34. Wind Generators
  35. Solar Power
  36. Hydro Power
  37. Watt & Sea Hydro Generator Review
  38. Battery Monitors, Part 1—Which Type Is Right For You?
  39. Battery Monitors, Part 2—Recommended Unit
  40. Battery Monitors, Part 3—Calibration and Use
  41. Battery Containment—Part 1
  42. Q&A—Are Battery Desulphators a Good Idea?
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