Features November 15, 2003 Issue

Chartplotter-Sounder Conversions

You can add a conversion kit and transducer to a chartplotter/radar display, and have robust sounder capabilities without needing another screen. We evaluate conversion kits from Garmin, Furuno and Raymarine.

There's a new breed of depthsounder that will allow your existing chartplotter or radar display to multi-task. The new technology allows those with limited electronics installation space to add a full-featured sounder/fishfinder to their navigational system without adding another electronics display. It's one of the hot new gadgets in the marine electronics market. Three of the major manufacturers already offer them—Garmin, Furuno and Raymarine—and just prior to press time we have word that JRC is joining the fray. 

Plotters from Garmin (top left), Furuno (top right) and Raymarine (bottom) are shown side-by-side with their conversion kits.

What We Tested
All three manufacturers agreed to send us their version of the sounder conversion kit. Garmin sent us its GSD 20 sounder module, Raymarine sent its DSM250 digital sounder module, and the Furuno shipped us its BBFF1 Network sounder.

Garmin introduced its black box sounder, the GSD 20, last year and started delivery this year. Raymarine's DSM250 digital sounder module hit the market this year, as well. It features what Raymarine calls HDFI (High Definition Fish Imaging) technology, which constantly adjusts transmitter and receiver parameters to analyze fish and bottom echoes and automatically produces a clear echo sounder display. The Raymarine DSM250 works with all hsb2-based Raymarine displays. This allows you to integrate the DSM250 to an hsb2 chartplotter or radar system display.

Furuno introduced its NavNet series almost two years ago. It relies heavily on the computer communication protocol of TCP/IP and Ethernet hubs to relay and share information. If this sounds familiar, it's because it's the same way home computers share information. The Furuno BBFF1 allows you to add a sonar system to your NavNet chartplotter or radar system.

How We Tested
We conducted a bench test, mounting the three systems on a piece of plywood. We did not test display qualities, or live-test the sonar systems. Our evaluation focused on how the black box sounders integrated with the display system. There was no transducer installation with this test.

We aimed to answer these questions for each unit: How difficult is it to add a black box to the system? What is the user interface like? And do you need to be a rocket scientist to use a black box sounder?

Garmin GSD 20 Sounder
We installed the GSD 20 sounder module with a GPSMAP 2010C chartplotter. The first step for interfacing the GSD 20 black-box sounder with the GPSMAP 2010C display is to upgrade the software version of the GPSMAP 2010C. We had difficulty upgrading the software, per the instructions in the manual. However, this only added about an extra 30 minutes to our set-up time and was not a serious issue.

Now with the proper software installed, we continued the rest of the installation, following the wiring diagrams. We were able to get the sounder interfaced to the GPSMAP 2010C display via two wires. This was the only system that we tested that had a bare-wire interface. The other two black box products offer molded connector wiring interfaces. We prefer the connector style of interface cable because it offers better water resistance.

With the GSD 20 black box sounder interfaced, the unit was now packed with sounder features. The best, we thought, is the split-screen feature of the chart and sounder. This function works exactly the way you would want to see it. One half of the display shows chart information and the other side shows the sounder display. We found an interesting feature that allows the user to define the size of the sounder display. In other words, the user can have the chart take up 75% of the display and the sounder information be shown on 25%—or any combination of size the user would like. The user can configure the map page with split sonar display and data fields. There were other features of the GSD 20 you would expect to see with standard big-screen sounders: water temperature trend (a graphical representation of water temp over time), fish symbol icons for target return displays, displaying of target depth information, a flasher display, zoom control and split zoom options, bottom lock, dual frequency operation (200kHz for water under 200 feet and 50kHz for water deeper than 200 feet), keel offset, and depth alarms.

We found the function menus for the sounder intuitive and very easy to navigate. Without a lot of head scratching, we were able to change the display configurations and data displays in more combinations than can be mentioned.

The GSD 20 black box sounder also has a flashing green light on the front of the module. This is a positive indicator to let the user know the system is functioning properly. However,when the unit is mounted on a bulkhead (typical installation), it is difficult to see if the green light is flashing.

There are as many display options and functions with the GSD 20 that you will find in stand-alone sounder systems from Garmin.

We also tested the GSD 20's ability to integrate with another display. This shows how two independent displays can share the sounder. These displays were not communicating with each other, but sharing the sounder. We had a bit of a problem reading the wiring diagram to set up the second display. The print was very small, and we noticed that the wiring diagram shows the two wires required to interface the second display being WHITE/RED and WHITE/BLACK on the display wiring harness. We would expect to see a white wire with a red or black tracer going in it. However the converse was true. The wires were red and black with white tracers. This applied to the wiring harness of the GPSMAP 2010C display also with WHITE/BLUE and WHITE/BROWN wires. This is important because someone who is not confident with his or her technical skills may be confused in hooking up the product. So it becomes a safety issue.

Bottom Line: The Garmin GSD 20 black box integrated with the chartplotter display with a slight amount of difficulty. It is the least expensive in our group, and the easiest to use. The bare wire interface is the unit's only real shortcoming,

Furuno BBFF1 Network Sounder
After mounting the NavNet 1803C display and BBFF1, connecting the two units was very easy. The supplied cable was constructed very well, with a strong and tight-fitting connector. This simple operation took no time at all—no wires to strip and splice.

As with the other two black box sounders tested, the BBFF1 has a green indicator light on the case to indicate a positive status. However, unlike the others, the light can be seen easily if it is mounted on a bulkhead.

Reading through the manual, we found that we could increase the output of the system to bump up the depth range via a simple jumper change inside the sounder unit. This is not a difficult procedure and even the non-technical user should be able to complete this task with a screwdriver and a pair of needle-nose pliers. When making these adjustments be sure you are installing a 1kW transducer. The operator's manual documents very well the styles and models of transducers that are available.

Remember, when you buy a black box sounder, you need to purchase a transducer.

The BBFF1 manual made good mention of installation requirements, like minimum mounting distance between the sounder box and electro-magnetically sensitive devices (magnetic compasses, VHF, SSB and cellular communication antenna cables).

The BBFF1 operator's manual did not have any instructions on how to operate the sounder. It just gave us installation instructions. We needed to refer to the 1803C display manual.

The initial setup of the system was not easy. We needed to refer to the operator's manual constantly to display information and change display settings and page configurations. There are seven basic display options available and six configured hot pages. We found that controlling the system via the six soft keys, the trackball control, and the enter knob is a little confusing.

After some practice, we started checking out the features. We selected our sounder display mode. We could choose from dual or single frequency, marker zoom, bottom zoom, or bottom lock. The display shows a LF (low frequency) for the 50 kHz frequency or HF (high frequency) for the 200 kHz frequency.

We could split the screens side by side or vertically. The BBFF1 offers automatic sounder operation. This is a great feature when you're preoccupied with other tasks and don't have time to adjust the display. There are two automatic modes—cruising and fishing. Cruising is for tracking the bottom, and fishing is for searching for, you guessed it, fish. The BBFF1 offers a manual mode for the operator to override the system's control of range and gain. There's a bottom alarm, fish alarm, and a combination bottom-lock/fish alarm function.

Integrating another display to this system would be completed via the NavNet network cable and an Ethernet hub—a modern and effective approach to sharing information onboard.

Bottom Line: The Furuno BBFF1 is a very powerful system with many options. It offers simple power conversion for greater depth readings or higher resolution at lesser depths. The smart design for bulkhead installation allows for easy confirmation of proper operation. Its complicated user interface is a drawback, but only a minor one because all you need is time with the machine.

Raymarine DSM250
The Raymarine DSM250 digital sounder module interfaces to a Pathfinder PLUS radar or chartplotter display via a single cable. If you have an older hsb (non PLUS) display unit you must upgrade to hsb2. The DSM250 works only with Raymarine hsb2 systems. You can do this by ordering an upgrade kit for about $300.

The DSM250 uses a high pulse rate that helps identify targets and the bottom with higher resolution. The system features automatic gain controls, auto frequency, and improved noise reduction functions.

Depending on the types of display you have connected to the hsb2 network, four full mode screens—sonar, chart, radar, and data log—can share the display with your sonar or chartplotter/radar display. And it can be done horizontally or vertically.

The user can control the transducer frequency and display 50 kHz and/or 200 kHz, use automatic or manual selection for scroll speed for bottom graph display, depth range units, STC and gain. Alarms can be set for deep water, shallow water or fish.

As with all of the systems tested, there is a vast array of display options and parameter controls. The DSM250 is a robust system that will allow you to operate at 600W RMS or 1kW RMS, depending on the style of transducer you select.

Like the Garmin, the DSM250 has a green indicator light mounted in a hard-to-see location.

Raymarine was the only manufacturer to supply the user with a laminated quick reference card. These cards are very useful and can save you time thumbing through the manual.

The user interface was almost as complicated as that on the Furuno BBFF1, and not as intuitive as the Garmin GSD 20. It was midway between the two. We found it not too difficult to navigate the soft keys and menus. However, if you're a first-time user, you'll appreciate the well-written and well laid-out manual.

The Raymarine DSM250 allows you to display sonar information on up to 10 hsb2 displays.

Bottom Line: The Raymarine DSM 250 strikes a definite middle ground between the products tested. The user interface is not as easy to navigate as the Garmin system; however, we thought it was more intuitive than the Furuno model. The sonar information and data displays offer greater flexibility than the Garmin system. The new concept in sounder design should offer better target resolution and easier target identification than its competitors.

Adding a black box sounder to your existing capable chartplotter or radar display is not difficult. You are able to share that information on multiple displays. All of the products tested offered a full function sounder with a simple installation. And no, you don't need to be a rocket scientist to configure and operate these units.

We like the Garmin best for its price, ease of installation and its intuitive and easy-to-use fishfinder menus and controls.

The Raymarine and Furuno products offer more power options and display information. The user-interface with the Furuno black box was not as easy to use as the Garmin or Raymarine product; however, working with the operator's manual to learn to control the system was not difficult—just time-consuming. The Furuno system offers the most information management, displays, and control for deep-water sounding.

The Raymarine setup has the most user-configurable displays and would be great for a multi-station layout on a larger vessel. It offers great flexibility for owners of that style of craft.

In addition, the Raymarine unit features a new design concept in sonar.


Also With Ths Article
Click here to view "Value Guide: Sounder Converter Boxes."

• Furuno, 800/343-9171; www.furuno.com
• Garmin, 800/800-1020; www.garmin.com
• Raymarine, 800/539-5539; www.raymarine.com

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