Units capable of doing practically everything are available, yet some boaters still prefer single-purpose electronics. Is there a "best" solution?

This question has been around since combo units first hit the shelves of marine-electronics dealers, and my answer has evolved along with the units. Three decades or so ago, it was common to see two or three separate units at a typical helm station on freshwater and inshore saltwater boats. There was always a sounder, often a navigation unit and sometimes a radar "scope."

A few years after the practice of networking electronics began to get serious traction among saltwater boaters, freshwater units combining sounders, and electronic navigation receivers were introduced. I first heard "the question" from proud owners of the new freshwater combo units.

Combo units were - and still are - especially popular for use on boats with limited console space and by boaters with limited budgets. They enable boaters with room to install only one box to take up that space with a unit that helped navigate as well as scan the water column beneath the hull. And since both functions share the same display, keypad and at least some internal brain power, a combo unit cost less than two separate single-purpose units.

Putting two functions into a single unit has always generated a few negatives along with all the positives. The most common complaint is that if the sounder breaks down and has to go in for service, your only navigation unit has to go with it.

Perhaps the second most common gripe concerns two functions sharing the same screen. When you are primarily concerned only with sounding or navigation, you can display the function full-screen and see it in maximum detail. When a situation calls for both sonar and navigation, you must split the screen and display each function with half of the screen's total area.

This isn't as much of a problem with units having 8- or 10-inch screens, but the boater who only has room for a combo model with a smaller display has to stay closer to the unit and maybe even squint a bit to absorb all the necessary detail. The older you get, the more trouble your eyes have with smaller screens (if you don't have gray hair yet, just trust me on this).

So if full-screen views and not losing both units when one has to be fixed makes more sense to you, is buying separate single-purpose units the best way to go? If your mounting room and budget can stand it, I'd say no.

Each generation of electronics seems to come with more networking capability, blurring the line between traditional single and multi-function units. Saltwater electronics have widely become multi-function displays fed by multiple single-purpose modules, although many still come with one function (notably sonar or GPS navigation) built-in and stand ready to accept other plug-in modules.

The same is happening with electronics popular with freshwater boaters. A few years ago, you could buy a Lowrance sonar unit, and add the company's digital broadband sonar module. Now broadband sonar is built into some HDS series units, and you can add radar and StructureScan side-scanning modules. You can also buy a stand-alone GPS navigation model, and add other modules to it.

So I think the optimal solution is to mount two combo units on a freshwater boat, and run full-screen navigation on one and full-screen sonar on the other. If a function breaks down on one of the units, you still have a backup that can do both jobs.

Saltwater skippers can do almost the same thing by running two multi-function displays, one showing sonar and one dedicated to GPS chart-plotting. If radar is important, a third screen might be needed, but overlaying the radar image onto the chart plotter might work just as well and save the need to buy that third screen.

The answer comes easy when I'm spending your money, but, of course, we all have to balance wants, needs and budgets. And, it's quite possible that this question will disappear completely in a few more generations of marine electronics as the networking trend evolves.