Marine technicians lament: terminally frustrated

I am going to let you in on a secret, so very many repairs carried out on boats, especially newer ones, could have been prevented if it was done right the first time in the factory. There is a difference between an item running its course, reaching the end of its useful life or, scheduled maintenance, I am referring to things that fail way too soon, in this instance termination, more specifically electrical termination.

"Oh no" I hear you moan, just as you decide to go somewhere else, well, let me remind you, the main cause of fires on boats is electrical related and, the main cause of technical intervention I would say is also something electrical related.

There are rules and guidelines for electrical installations on boats, both in the USA and Europe, I would suggest the USA regulations might be a bit more complete and strict, CE regulations in Europe are law, so, if this is the case, why do we still keep seeing electrical terminations that are sub par? We all know that boats live in water, salt water (let alone bilge water) is an especially corrosive environment, so, rules and regulations aside, it would make common sense to try and keep our electrical connections and terminations as secure and dry as possible? Well, sometimes I have to wander what on earth is going on.

It drives me (wiring) nuts

Wiring nuts are a big no on a boat, I can never remember if they are prohibited for use on boats in the USA or just not recommended, there is definitely some guidelines or rules in place for these little monsters, good job too. Wiring nuts or similar connectors are commonly used in residential electrical work, usually for joining or "commoning" cables together.

Image 1: Factory wiring nuts (Euro style) on a brand new boat, disappointing

Image 1:Take a look at the above photo, this was taken on a brand new Italian boat costing north of 600K, you cannot imagine the number of those types of connections I have removed from boats because they have failed or got loose, if you are lucky you can find them before the wires get corroded, I have also seen "professionals" use these for electronics installations, not good. I am also not very impressed with the plywood backing board or the cable tie not cut flush, just waiting to stab you when you least expect it. I have no idea what these cables are for or where the other ends are connected, tinned copper also would be a better choice over plain bare copper stranded wire.

Image 2: Some more examples of why not to use these types of terminals

Image 2: A look at the two above photos, both of which taken on Italian boats where the yard really should know better. Left: Those wiring nuts did not offer much protection from the bilge water, even fitted in a box, cable glands would have helped keep some of the water at bay, also fitting the junction box higher up out of the bilge would have been better. Right: that box and those terminals were connected to the main shorepower inlet, so mains electricity, this yacht new was over a million Euros.

At my wits (terminal) end

Cable end terminals, also known as ferrules or bootlace ferrules, they are a professional way of terminating cables, some typical uses include shorepower cables, DIN rail terminal blocks such as those from Wago, very fine cables used to go into circuits boards or screw down terminal strips such as the back of battery monitors. The idea of these terminals is so as not to insert stranded cable straight into a screw down terminal and have the wires splay open, once again I think the USA leads Europe on guidelines and rules on this.

Image 3: Ferrule crimp tool

Image 3: The tool in the photos is mine, made by Knipex from Germany, it can crimp ferrules of up to 16mm2. This is the square crimp style, hexagonal is another common profile. The lever is for switching between terminal sizes, up to 10mm2 and then up to 16mm2. Larger than 16mm2 is available but usually the tool will only crimp one or two sizes of cable. Although I don´t crimp 16mm2 that often, it is very helpful to have for things like music amplifier installations.

Image 4: terminated cables using ferrules

Image 4: This is what ferrules look like when crimped, these are on a shore power cable before being inserted into the dockside plug.

Image 5: Ferrules seen from behind an electrical panel

Image 5: This is what ferrules look like from behind an electrical panel. In this case this is a small mains electrical panel with double pole breakers (breaks both phase/live and neutral), the original cables were just pushed into the back of the breakers and the screws tightened down, ferrules are a much neater alternative.

Terminal strips

Terminal strips get used in all kinds of places, a lot of small electronic devices use them as a convenient method of attaching cables to circuit boards, they are also a very convenient method of joining cables of different thickness in a secure way, avoiding stripping a larger diameter cable down to fit into a smaller terminal or trying to roll and double a small diameter cable many times to fit into a larger terminal. Terminal strips are also useful in fault finding as you can touch the terminals with a multimeter probe to check for continuity & measure voltage, you can find them very often in boats behind electronics panels where the main positive feeder cables are larger diameter than the power cables preinstalled on plotters or VHF radios.

Image 6: Two terminal strips with ring terminals and screws

Image 6: Two examples of terminal strips in use, left: mains connection, this terminal strip has been fitted inside a waterproof box. Right: terminal strip used to make connections for an NMEA2000 converter, note the heat shrink ring terminals and the difference in the diameter of the cables, in a perfect world, the smaller diameter cables on the top row would have been used a smaller crimp terminal, probably uninsulated and then heatshrunk after.

Image 7: View of a terminal strip on an inverter

Image 7: A terminal strip installed on an inverter (a device that turns battery power into mains electricity), This is not a good example of an installation done well, ferrule terminals should have been used on the cables going into the terminal strip, the white insulation on the three core cable going into the inverter should be better protection from abrasion too, this is how the factory installed the inverter on the boat, the rest of the inverter installation was also bad.

You might well have seen the type of terminal strips as in image 7 used elsewhere, they are not suited for general use on boats, they are known elsewhere as "chocolate blocks", "dominoes" and various other names, they can be cut into smaller blocks for fewer circuits. They are generally not made of an adequately corrosion resistant material, they should be used with ferrule terminals but generally aren't and, no matter how much insulating tape you put over them, they do not offer much protection against the inherently corrosive marine environment. I have seen them placed inside an IPX rated box, this can work.

Image 8: Do not use terminal strips like this

Image 8: The more you look at these photos and the worse it gets. The owner of this boat paid a "professional" company to install a generator on their boat, this is how they did it, running the mains electrical feed from the generator to the shorepower input, they used bits of terminal strip to make the connection behind a transom panel fully exposed to the bathing platform, we ended up redoing the entire installation, the things we saw I could write a whole new post on, I repeat a boat owner paid a lot of money to a nautical company in a boatyard to do this.

Where not to use terminal strips

Image 9: When not to use terminal strips

Image 9: Oh dear, these are some examples of when not to use terminal strips, no matter how convenient it seems. Top 3 photos: These were taken quite recently, the two photos with the black terminals are from a trim tab pump, the boat owner asked someone to replace the original hydraulic pump, this is how they made the connections, as you can imagine, it did not work for long, these terminals were partly covered in electrical tape and then hidden inside some cable conduit. The white terminal strip was being used for a toilet macerator pump, you will notice the discoloration, the yellowing, this is caused by heat, the cables had been inserted without ferrules and the fine wires crushed by the screw fixing. Bottom: I cannot say for sure what caused the burn marks on the ceiling of this cabin, you can see in the photo the terminal strip being used to attach the larger diameter feeder cables to the finer cables of the lamp.

Conclusion

The intention of this post was not to be alarmist, more to show a better way to terminate cables, factories are every bit as guilty as the home electrician. The required tools need not be expensive, but, I assure you will come in handier than you ever though possible.

I have seen some installations that would have NASA engineers nod their heads in approval, such was the care taken and effort made to do things correctly, I have seen others, including from well known boatbuilders that looked like a plate of spaghetti had exploded in a paint factory. The problems of not having things done correctly first time around are many, apart from early failure of electrical installations, the person who comes behind will often look and copy what was there previously, it´s completely normal, if the factory did it like this, it must be correct. Lets raise standards and stay safe.

I hope you have enjoyed reading this post, please feel free to follow me on social media.