In the previous two articles we have reviewed several different types of SONAR equipment with a variety of capabilities and significant price differentials.

So, what are we to make of all of this? To begin with, we have passaged well over 250,000 miles in all sorts of remote and poorly charted areas, with just a depth sounder and our wits to keep us out of trouble. Sure, some form of SONAR would have been nice, but we’ve gotten along without it all of these years. So why change now?

Times have changed. There’s been huge progress in signal processing, and the hardware that is available. For modest cost, one can now get what looks like a simple but functional forward-looking SONAR, which could definitely be an advantage in some situations. For a larger budget, a fully controllable unit – such as what we sea-trialed from Furuno – would, as we’ve already indicated, be really cool.

The decision for us – and probably for you – is based on budget, space, complexity, risk factors and need. We are comfortable with the risk factors in the tropics and our ability to deal with them without this gear. In higher latitudes, if you stay in the more traveled areas, with good local knowledge and a comfortable level of chart detail, a simple depth sounder and prudence will get the job done. But in our own case, we are looking at cruising in remote areas where charts are old and typically inaccurate. Add in cold, wet weather, which reduces our interest in doing dinghy surveys, and some form of SONAR begins to sound appealing.

But if we (or you) are going to have this gear aboard, as we have already mentioned, it is critical to spend time with the SONAR to get used to interpreting the data. This means using the system in situations where the bottom is a known factor, and then comparing what the SONAR is showing to the real world. This way, when we are in unknown situations, perhaps with a bit of adrenaline flowing, we will be able to efficiently take advantage of the SONAR images. Short of investing the time and effort in learning to really use this gear, it is better left ashore.

John Lindstrom is a principle at Baytronics South ( www.baytronics.com ) in Southern California. He has been a reference source for real-world data for us over many years. He sells Furuno and other equipment, and services yachts with all types of electronics. We chatted with John in an attempt to put all of this into perspective.

John’s first comment was that:

"…None of this equipment would work offshore in any type of sea to give you warning of floating debris. In smoother conditions Furuno gear would have the best chance of spotting a container. The smaller, simpler systems, however, are good only for nosing into anchorages."

We then asked John Lindstrom if he’d had any experience with the other gear. He said his first choice for a simple vertical mode presentation would be Echo Pilot from the UK. In this regard, he echoed (no pun intended) John Harries’ experience with Echo Pilot.

We also wanted to know about his experience with Furuno’s SONAR. In particular, we have some concerns about the complexity of the motors, linkages, and various moving parts. Lindstrom’s reply was that "this is mature equipment, with very few service issues."

We have come to the conclusion that some form of SONAR makes sense for our cruising in the high latitudes. There may also be an application in the tropics, if weather or some other issue forces travel in coral-infested waters during periods of poor visibility.

We still have some thinking to do about which equipment makes the best sense for our needs. We’ll keep you posted.