Sidelong View

 
Sonar is a great fish-finding device, but it has a lot to offer as a navigational tool, too.

By Glenn Law

As a complement to an electronics suite, fish finders are very sophisticated. They are great at doing what they were designed to accomplish: show you what the bottom looks like and help you locate fish, so long as they are swimming underneath your boat. However, if you give a standard fish finder a new orientation — let it scan ahead of the boat or to the side instead of straight down — a whole new world of information opens up for the helmsman. This is the realm of side-scanning sonar, and while it has yet to get its due at a lot of helms, the technology can provide a picture of your charted waters that's not available anywhere else.

Side- and forward-scanning sonar have been likened to underwater radar. The obvious application is to use it to locate fish that may be just a cast away, but it can be a valuable navigational tool, since it offers a view of the entire water column in the direction of travel. Just how much sonar can do for you depends on the configuration you chose to install. We'll look at three types in this column.

If fishing is not what occupies most of your time on the water, step up to forward-looking sonar. With this technology, the nav functions become just as prominent as the fish-finding abilities.

Unlike other units with a fixed-view transducer, Interphase Technologies uses a phased-array transducer to scan a 90-degree field ahead of the boat, creating an image of what's underwater in the direction
of travel up to 1,000 feet ahead. The Interphase SE-200 Sonar Engine single-transducer unit (interphase.com) is $2,100. The paired-transducer model, with a 180-degree forward view, is $3,200.

More than half of the sonars sold by Interphase are for navigation, according to company president Charles Hicks. "The cruising powerboaters lead the charge," he says. "Most of our customers have boats in the 40- to 60-foot range."

Hicks says his customers are of two types: offshore cruisers concerned with hitting logs or abandoned shipping containers in the open ocean and the larger market of inshore cruisers who have to deal with shallow water. "The majority of users are concerned with unknown shallow areas," he says, whether they are in Florida, the islands or cruising the East Coast in the ICW. "We also see a lot of cruisers using them in the Pacific Northwest, where there are rock pinnacles, many of them not marked on the charts. You can use a traditional depth sounder that looks straight down and gets the depth underneath, but nothing else looks out there and shows you there is a rock 40 feet ahead."

The SE-200 is available with its own sunlight-viewable 7-inch display and with both video and VGA output. It's designed to integrate with Raymarine, Garmin, Navman, Northstar, Simrad and Furuno displays, as well as PC navigation systems and flat-panel stand-alone monitors, like the TV you have belowdecks.

Side-scanners that provide a 360-degree view around the boat are available from Furuno (furuno.com). Its CH-270 is a sophisticated, dual-frequency system and pricey at $13,995. Installation requires a sea chest on the boat and a 6-inch tube running down the hull (like an upside-down periscope) through which the motorized scanning transducer is deployed. Individual fish and underwater structure are displayed on a 10.4-inch color LCD screen in up to 16 colors. The bulk of installations, says Steve Bradburn, assistant product manager for Furuno, is in serious fishing boats. "There are big tournaments out there where one fish might be worth a million bucks," he says, "and if you don't have an expensive sonar and others do, you are at an extreme disadvantage."

Anglers find great value in the unit, but serious cruisers rely on it as well. "I've seen guys put it on 30-foot boats," says Bradburn. "It's not really for the casual weekend boater, but it is a good tool for those who travel distances. I live in Seattle, and you don't need this for the San Juans and Puget Sound, where the charts are good." However, Bradburn says the unit is indispensable for those who run in areas that aren't well-marked. "If you start poking around in small coves in Alaska or try to use foreign charts when in Mexico, you can throw those charts out the window," he says.

While a system this sophisticated requires a significant commitment in installation and cost, the investment is often a good one. "The bigger the boat, the more expensive it is, but the more room you have," says Bradburn. "When you calculate the expense of putting a boat aground versus the price of the sonar, its not that big a deal."

From Lowrance (lowrance.com) there is Structure Scan. This is a side-scanning module dedicated to finding fish, and it's the latest addition to the company's HDS Series. Structure Scan offers a fixed, lateral view of the water column to the side of the boat. Because it's so new, details have not yet been released, but the company says it is designed to provide a fixed-beam view of the water column. As a navigational tool, it's limited, but for finding fish and viewing underwater structure, the resolution of this type of sonar is high-quality and intuitive. "The purpose is to provide a side-viewing, detailed image of the underwater structure," says Gordon Sprouse, the director of marketing for Navico, Lowrance's parent company.

With a retail price near $695, Structure Scan can be networked with all Lowrance HDS Series electronics. The kit includes Ethernet cabling, a transducer and a black-box module that networks with all of the plotters, fish finders and combo units in the HDS series, and it's equipped to feed multiple displays. "You can have the sonar image available at multiple places in the boat," says Sprouse.

Other New Electronics featured this month:

• New Navigational Software
• Tools for Cruising
• Chart Your Options
• Cruising Companion
• Keep It Simple, Skipper

Electronics Archive

• More Electronics from past issues.