The importance of your yacht's digital plumbing

We live in a digital, computerized world that has proliferated, especially on board the modern yacht, and includes the following systems: monitoring/instrumentation, entertainment, VOIP telephone, satellite communications, at sea Internet, intercom/PA, fire alarm, bilge alarm, security alarm, vessel management, integrated bridge/navigation, and onboard computer/LAN. These are just a few, however all of these systems basically consist of the three following building blocks:  


• Hardware is the actual physical electronic circuits, modules, devices that take the input data/signals and electronically perform a conversion process on them to provide a different output. This process is known as I-C-O which of course means Input-Conversion-Output, and no matter how complex the electronic circuits may get they are basically designed to facilitate various conversions from different types of inputs and convert them to something more useful or usable. For instance, your boat's weather station is taking in physical data from various sensors and converting it so that it can be displayed in images/graphs in the pilot house or up on the bridge.


• Software is a form of electronic instructions that tell the other electronic circuits what conversions to perform and how to do them. This is what makes modern electronics so versatile, because the outputs can be modified and changed without designing and building a whole new and dedicated circuit board.


• Cabling, which we will hereafter refer to as digital plumbing due to its analogous function of a water pipe that delivers a stream of water, the cabling delivers a stream of data bits which is then turned into something more useful by our hardware/black box. From now on, due to the complexity of the circuitry inside our physical hardware, I want you to think of the hardware in terms of a black box that receives information from our cabling/plumbing, acts upon this information through various conversion processes governed by its software load and finally outputs something useful for our enjoyment, safety, or to just plain make our work easier. 


Another reason to think of the hardware in terms of a black box is because if it breaks it is not economically sensible to repair. Also, due to its complexity and degree of integration, hardware is beyond the technical abilities of most people to troubleshoot and repair. This, of course, does not apply to the simple fixes such as making sure it has power, is properly set up and operated, and that an occasional blown fuse is replaced. The really good news is that the hardware is usually the most reliable component of most modern networks or local area networks (LANs), the software is usually very reliable unless there is a big change to the system/network. That leaves the plumbing, which is typically the cause of more than 70 percent of network problems. The plumbing is the one part of the overall system that we can easily troubleshoot and repair.


Determining that a problem exists

Just about every piece of hardware/black box have condition LEDs and these can be very helpful in diagnosing if a problem exists. LEDs come in different colors, usually green, yellow, and red and can exhibit one of three states &mdash on, off, or blinking. The color and state of these LEDs is important and you must read the device's technical documentation to see what they are telling you. "Power" and "Link" lights are especially important. When the link is down it is time to check the cabling and any all-important and ubiquitous RJ-45, eight-pin modular plugs.

Make sure that the RJ-45 plug is securely locked into its jack and at the same time wiggle the cable while observing the condition LEDs. If this does not restore functionality then it could be the other end of the cabling, so have someone do the same check on the far end while you continue to watch the LEDs. If the problem still exists it is time to check out the integrity of the whole cable. This calls for a cable checker. The cable checker will come with a loopback plug that you attach to the far end of the cable, plug the near end into the main cable checker and push the test button. The checker will indicate if you have electrical continuity through the cable conductors and how they are wired, straight through or crossover.

If the cable fails the continuity test then replace the RJ-45 plug on one end and retest before going through the work of changing the other. These modular connectors were originally developed by the telephone industry and use what is known as IDC (insulation displacement connectors), because when you crimp them down you are piercing the conductor insulation. The connections are usually pretty robust if done correctly, but may become loose or undone due to severe vibration or other harsh environmental factors.

The secret of reconnecting RJ-45 plugs is to make sure that you pin them out correctly by following the original connector pin out. There are eight wires in an RJ-45 plug and they must be in the proper color sequence. You must hold the replacement plug upside down, with pins up and lock clip down before inserting the wires. For your information while holding the RJ-45 upside down, pin No. 1 is the far left one and pin No. 8 is the far right one. If you have reconnected the cable properly then it should retest "okay" and when you plug it back into the network the "link" LED should light up again. Job well done!

Let me warn you, the above procedure is not as easy as it sounds and, like anything technical, requires practice. I suggest that you practice your skills by making a few spare cables to be used in an emergency. WARNING &mdash UNDER NO CIRCUMSTANCES SHOULD YOU DISCONNECT AN RJ-45 FROM ITS JACK WHILE YOUR VESSEL IS UNDERWAY UNLESS YOU KNOW FOR SURE THAT IT WILL NOT AFFECT THE SAFE NAVIGATION AND CONTROL OF YOUR VESSEL! I cannot emphasize this enough and it is always best to work on cabling while in port or while anchored out and not underway.



I would recommend that if you have just a few RJ-45 connected cables on your vessel that you buy some spares commercially and carry them on board, just in case. If your vessel has lots of RJ-45s then it may behoove you to procure the Professional Network Installer Tool Kit from Radio Shack online. This is an excellent kit that only costs $152.49 and contains the following LAN tools:


RJ-45/-11 Crimp Tool

110/66 impact punch-down tool

Wire stripper

Several RJ-45 connectors

RJ-45 network cable tester with remote loopback plug


At just type "LAN kit" in the search window and it will take you right to the product.

I recommend the following vendors that were very helpful to me: To buy spare cables commercially and to receive a free and very useful "Pocket Glossary of Computer Terms" go to Karen Dugan (949) 252-0245 at Dugan Data Inc. E-mail or visit

For experts in serial and data communications I recommend visiting B&B electronics at

Regards & Smooth Sailing



About the author:

Fredrick Gary Hareland holds an AAS degree in rescue and survival operations and in avionic systems technology and is a certified marine electronics technician and NARTE certified telecommunications technician. He has served in the U.S. Navy, Coast Guard, the Military Sealift Command-Pacific and has worked for Maersk Line Limited and Norwegian Cruise Line. Hareland currently works at China Lake Naval Air Warfare Station as a microwave-communications technician. He lives in Ridgecrest, Calif.

By Ocean Navigator