BY OCEAN EYE, INC.’S CHRIS GABEL
So, you’re ready to get in the water for that project that’s been months in the making. Everything is in place and you and your dive crew are ready to get the job done. You do a last communications check to make sure everything worked like it did in the dive locker. Then you get that sinking feeling when you can’t hear the dive supervisor on the topside radio, or they can hear you but you hear nothing. The dive is off.
So, what happened? Well, it could be one simple thing or a combination of several things. In this article, we’re going to take a look at the most vulnerable parts of the communications line on the umbilical – the ends. Whether it’s two wire/post connections on the helmet or four wire Marsh Marine, it’s always a bad feeling when your comms don’t do what their supposed to.
For this first part of the article, we’re going to focus on the two-wire communications line. In the next issue, we’ll go over Marsh Marine troubleshooting. For both of these issues, we’re not going over the individual helmet components like the speakers and mic. Another assumption is that some joker didn’t re-wire your topside connections and not tell anyone.
The partial good news is that when you are running a two-wire configuration, it’s the simpler of the two configurations. When you have a problem with one of the wires, then the entire system doesn’t work. Typically, the first thing that we look for, and many times find, is an issue with rotting on the diver end. Copper wire reacts like copper reacts in water after some time. It starts turning black and continuity fails. You can cut the wire back and re-strip the end. A lot of the time that works with a minimum of wire cutting. Other times, you are going to have to cut several feet back and try that same evolution again. I’ve had to cut as much as 6 feet or more back to get to decent wire. That’s why it’s so important to make sure you have a length of sacrificial wire installed when you configure your umbilical. Otherwise, you end up with a shorter communications cable than airline. That’s just embarrassing.
So, what to do. First, a simple visual check. Do you have a broken wire end that’s still in the banana plug on the topside end? Did someone hit the wire with a hydraulic chainsaw? Look for the obvious things first. What happens if everything appears fine? If you have a multimeter, check the continuity for both legs of your wire. Most likely you will find one of the two sides are DOA. Not the case? Then you either have an issue with the radio or the components in the helmet. The likelihood that it’s all three helmet parts (two speakers and the mic) is highly unlikely. On a two-wire system especially, you hope that you have enough sacrificial wire. The reality is that at some point you are going to have to cut some wire back. If you’re running short on wire, you can splice more in using an underground/underwater splice kit. Now, if you’re going to go and splice wire you need to keep something in mind. Are you using a wire that has an integrated strength member as many are now? Then you are going to need to splice the additional wire after your D-Ring. If your umbilical has an additional rope line strength member, then it’s not as important where the splice is located. Make sure that you install a good quality waterproof splice kit so that you don’t have rotting coming from the bare wire at the diver and wiring at the splice kit. That becomes both embarrassing and frustrating. There is going to be a fair amount of cursing involved when trying to troubleshoot those issues.
I have a humble suggestion when it comes to splicing no matter what configuration you’re using. I’ve started installing line stress relief bridging. Why? Remember when you were very young and your parents would yell at you when you pulled a plug out of the wall from across the room? It seemed like a good idea to you, it saved several steps, but really made your Mom angry. That’s because you weren’t pulling the plug at the strong point around the root of the plug and ran a strong chance of breaking the wires internally. The same thing applies here. Tenders are not supposed to pull the entire hose by the communications ends but you know it happens. A line bridge gives you a little more insurance for the longevity of the ends. If you want to see what one looks like, you can look at this YouTube link: https://youtu.be/TZPn5xV63Dk.
Stay tuned for my next column where I’ll cover troubleshooting Marsh Marine communications.
Chris Gabel is the president of the award-winning veteran-owned company Ocean Eye, Inc. Chris works with companies and government entities to create safer and more profitable environments. Chris’ articles on commercial diving equipment and safety have been featured in several different industry magazines and translated into multiple languages. He is a member of the ADCI Dive Safety Committee and has himself been diving since 1988.