© David Kerr 2001-2004

Which is the GPS Hand-held for you?

David Kerr reports on a variety of hand-held GPS units which he tested for Cruising Helmsman. Each GPS had features common to all as well as specific characteristics which are usually the decisive factor in a buying decision. David also tested a remarkable wrist-GPS which is barely larger than a diving watch.

Cruising with GPS

Implementation of the Global Positioning System (GPS) revolutionised navigation, particularly on boats. GPS receivers come in all shapes and sizes from ultra small portable units up to GPS integrated with chart plotters, autopilots, sonars and EPIRBs.

You only have to look at the bewildering variety of GPSs in marine electronics stores to realise that this is a big market and the microprocessor revolution has enabled the manufacturers to deliver many features in pocket-sized packages.

Why buy a hand-held GPS?

Cruisers usually buy a hand-held GPS for one of two reasons:

1. Electronics and wiring on boats can be impacted by lightning or simply fail. Most cruisers carry a spare hand-held GPS as security against malfunction of the main unit. The spare must be capable of running on its own batteries and ideally should be loaded with routes and/or waypoints for the current passage. Some cruisers, myself included, also carry a sextant and small, waterproofed navigation computer.

2. It is perfectly feasible to use a hand-held device as your main GPS. If you wish, this can be linked to an autopilot and other instruments to form a modular system. A system like this can save cost and in its simplest form consists only of the GPS, a mount and a power cable. A modular system enables you to save on power consumption. For instance, you need only run the low powered GPS for an anchor alarm or when navigating offshore instead of a chart plotter system.

The store perspective

I interviewed Grant Watson, the manager of Whitworth's largest store in Australia, to get his perspective on GPS buying patterns. Here are his key points:

1. Frequently, buyers are purchasing their first GPS and do not know much about the topic. Advice: Become knowledgeable about GPS and determine your requirements and your expected usage before you start the purchasing process.

2. A common reason for dissatisfaction is the user's inability to read the display, particularly in conditions of poor light or inclement weather. Advice: Check font sizes and see if the character size can be altered, particularly if your eyesight is less than perfect or you want to read the display without resding glasses.

3. All brands sold by Whitworths have been extremely reliable over many years. The very few failures have all been caused by salt water ingress probably after submersion. Hand held GPSs rate as one of the most reliable pieces of marine electronics you can buy.

4. Increasingly, units can easily be upgraded with the latest software to fix bugs or add features. This can usually be done by the user.

5. Whitworth's largest individual volume seller is the Garmin GPS72, however all brands and models sell well.

6. Some people want extensive electronic charts but fail to think about their cost. For instance, electronic charts for all of Australia can be thousands of dollars and dwarf the GPS price so it is worth considering a larger GPS when first you buy.

My testing

I focussed on hand-held marine units and asked the Australian importers to supply one unit from the bottom end of their range and another from the high end. Lowrance , Garmin, Magellan and Suunto responded. We tried to track down a current importer for the French MLR but were unsuccessful. The previous importers no longer represent MLR and the Corporate MLR Web Site does not show either Australia or New Zealand. MLRs are still available in some retail stores but I did not test them.

What did I look for?

I was looking ease of use and suitability of the units for one of the two roles described earlier. I also wanted to provide cruisers with a good idea of the features which might be most relevant to them.

What are the minimum requirements?

I should qualify this by saying that these are my requirements and yours will undoubtedly be a little different. That aside, I trust the following will help you formulate your own list:

1. Number of Routes and number of Waypoints. If your cruising is extensive, then you need as many routes and waypoints as possible. I think 20 reversible routes and 500 Waypoints are a good starting point. I already have 180 routes and 1,000 waypoints shared between my own two GPSs and a laptop and can envisage doubling that number over the next couple of years.

2. The ability to link to a computer or other device will save time creating or replacing waypoints and other data. The alternative is to enter characters by scrolling through the alphabet for each one.

3. Basic navigation functions and displays are important. For instance, the ability to follow a route, while displaying cross track error, distance made good, distance to go, courses, bearings etc. There is not enough space to describe everything you need; the good news is that all units tested more than satisfied what I regard as the minimum cruising requirements. Velocity Made Good (VMG) is a feature lacking on many early GPSs but now largely standard.

4. If you want a GPS as backup, then battery life and water resistance are important. A unit in a cradle needs to derive power from the yacht and run on batteries if that power is disrupted. Preferably, there should also be an NMEA output. NMEA is an industry standard accepted by most marine instrumentation.

5. Alarms in general but at least anchor alarms and proximity alarms for dangerous or special locations.

6. If you want to use a GPS in a steel or concrete boat, you also need an external antenna and and a suitable socket.

7. Track recording, display and the ability to backtrack are very useful. You should be able to set up the way points are saved. I have also used tracks for tuning the boat, measuring tacking angles, estimating leeway and determining the optimum time tack time when close hauled.

GPS accuracy

Now that the US Government (which controls and runs the GPS system) has turned off Selective Availability (SA), the horizontal accuracy of GPS readings will be plus or minus about 6 metres most of the time instead of the 100 metres during the SA period when the US deliberately “dithered” the GPS readings to gain an advantage over potential enemies. Note that the US Government reserves the right to restart SA or even turn the GPS system off! See the WAAS box for more information on accuracy.

As a part of my testing, I took the coordinates of a fixed point at the same time of day with each GPS. I also performed a real time comparison. Units compared at the same time and location agreed with one another to within a thousandth of a minute (about 1.8metres). Over a period of four weeks, all units showed my test point to be within plus or minus six metres, which agrees well with the figures quoted by the manufacturers. Each of the handholds showed similar signal strength and the same satellites. In other words, the differences between GPS receivers, mathematical processing and their antennas was very small. The estimated precisions were all close to reality. No unit would work under a tiled roof with a ceiling. All units worked on our GRP boat (near a Lexan window). Indeed, the signal strength and number of satellites was almost as good as with an external antenna.

How they stacked up

The table should give you a good idea of how the units compare.

All the GPSs were easy to use, were a good shape/size and most functions were intuitive. Occasionally I needed the manual. If you have not previously used a GPS, you will definitely need to read the manual. All the manuals are available for downloading from the Internet and I suggest you peruse them before buying any GPS.

Mounts are available for all the hand-helds. Cables to allow 12V power, PC interconnect or NMEA connection to other instruments are also readily available.

Each tested hand-held uses 2xAA cells. I trialled rechargeable Alkaline batteries in all of them except the Suunto. I have been using these batteries in my own GPS for a couple of years with great success and they worked fine in all units I evaluated.

Only one supplier (Magellan) supplied detailed charts and these really showed off their unit to advantage. If you are buying a GPS with charting capability, make sure you try it in the shop with electronic charts, even if you are not buying charts until later.

All units can be configured for metric, imperial or nautical displays. Each GPS also has a range of other useful features not documented here. Each of them is highly usable as a relatively complete navigation device with the major functionality you will require on water or land.

Suunto M9 Watch-GPS

I was really surprised by the long list of features and the M9's reasonable size. With dual time alarm watch, 500 waypoints, 50 routes, compass, thermometer, recording barograph, computer interface and rechargeable Lithium Ion battery it is a comprehensive product. The ingenious docking station allows the battery to be charged and the “watch” to communicate with a computer. I installed the software and soon had it communicating with the M9, uploading and downloading waypoints. The M9 is expensive, but registered users have access to worldwide electronic charts via the Internet. This allows you to generate routes/waypoints and also display your past tracks on charts at no additional cost!

The Suunto was not as sensitive as the hand-held receivers in the GPS position and sensitivity test, but still perfectly adequate.

You cannot run the computer interface and the GPS simultaneously so it will be a while before you see an M9 strapped into a cradle on the Nav station driving a computer, autopilot and all sorts of other devices! The sophisticated racing features can be used for some aspects of cruising.

Electronic charts may be purchased for RRP$300 per set of five. Battery life between charges (maximum 500) depends upon back lighting and GPS usage. I ran it for several days on a quarter charge.

Garmin GPSMap76

Both the Garmins have big screens and the resolution of the GPSMap76 is excellent. Big screens and many pixels (dots on the screen) make for good readability. The only gripe with this unit was the fact that it computes tides only for the USA. Garmin is allegedly fixing this, but I couldn't find a time.

A really nice feature of both Garmins is that fonts can be set to different sizes. This is in addition to the configurable screens.

A Base map was provided, but not detailed charts. I have used another GPSMap with charts and it was good. The Bluechart CD at RRP $395.00 gives you access to a selected region of Aus/NZ coastline with additional areas available for RRP $285.00 each.

Garmin GPS72

The GPS72 looks the same as the 76, but has a lower resolution screen. It has the same features without map capability. The Garmin “Points Of Presence” are quite detailed for Australia and surrounding regions. Most lights and other Navaids are shown with pertinent details. One word of caution, the positions are not always totally accurate (on any GPS) and I have found some of them to be several hundred metres out. However, they do give you an excellent idea of the navaids in a particular area. New revisions can be downloaded from the Internet.

Garmin general

There are seven current Garmin Marine models. There is a GPSMAP76 S model with 24Mb of map memory, barometer, PC cable and fluxgate compass but only 10hr battery life.

Lowrance iFinder

The Lowrance was more like a web based computer than the other GPSs and had an excellent search capability. I found it very easy to use with good “on screen” help and scrolling features. A really neat feature is its use of Multimedia Cards (MMC) for downloadable memory and information transfer. MMCs are one of the standard memory cards used with computers and digital cameras and they can be used to give the Lowrance more memory than any of the other units, but you do need some extra Lowrance software. Other nice features were the ability to switch between Simple and Advanced modes and various timers and alarms.

Screens were not as configurable as other units and the GPS did not have large font options.

The iFinder is not waterproof (it has splash resistance to IPX2 standards) but is supplied with a waterproof bag. There are actually four models in the US iFinder range and the model tested here was the entry model. They are all very similar, but only the tested model is available in Australia. There are only limited mapping options available for Aus/NZ.

Magellan SporTrak Colour

This unit had the best user manual and the best display due to the large number of pixels and the use of colour for menus as well as for mapping. No other tested GPS had a colour screen. Magellan thoughtfully loaded up East Coast Australia marine charts plus land maps on the unit I tested. These were impressive, particularly on the maximum-detail settings and the unit was very usable as a small chart plotter. Ease of use and customising options were excellent.

Magellan SporTrak

The SporTrak is the lower resolution, black and white, non-mapping cousin of the SporTrak Colour. It has many of the same good features, including the excellent manual. However unlike the SporTrak Colour, the right and left arrow keys double up for zoom. This is messy. The Points of Interest and Navaids are good

Magellan general

There are nine US Magellan models, of which four are available in Aus/NZ. The SporTrak Colour has a large 11Mb of basemap memory as well as the downloadable area. There are various chart options. The MapSend BlueNav Kit which has all local Australian charts is RRP$475.20, which sounds like a very attractive price.

Summary

All units performed well. The best GPS for you will be determined by your specific requirements and the features of the individual product. If money was no object and someone wanted to give me a hand-held, I would choose the Magellan SporTrak Colour (with a whole heap of charts thrown in). If I didn't want charts but wanted good value for money, I would choose the Garmin GPS72 (the Whitworths best seller). The Lowrance is also good value and the cheapest tested. I would be happy to receive a Suunto wrist GPS any time- what a great innovation, especially for small boat sailors, kayakers and other adventurers.

Table 1- GPS comparison of selected features

Notes: We believe that the specifications and prices were accurate as we went to press but neither the author nor Cruising Helmsman take any responsibility for errors.

# Detailed Base map for Australia & some world detail

? Not in marketing material, manual and unavailable from supplier.

Box 1

What is WAAS?

Many GPSs now directly support the “Wide Area Augmentation Scheme”. In the US, WAAS increases GPS positional accuracy to approximately 1.5 metres horizontally and dramatically improves altitude accuracy to about 3 to 5 metres. WAAS was developed to aid aircraft movements and will replace older air navigation systems. It is possible to receive WAAS satellite signals in Australia, but there is no benefit as the necessary land stations have not yet been established in our region. DGPS (Differential GPS) is the other way to improve GPS accuracy but it requires a special low frequency receiver to feed the GPS (and usually occupies the sole interface port).

Box 2

Web addresses

Box 3

Software

Software is available from the manufacturers and there is also good shareware available on the Internet for backing up your GPS data, entering data, plotting on scanned or electronic charts, sharing among several GPSs and downloading waypoints and routes.

Author Box:

David Kerr is a regular contributor who has a keen interest in sailing and technology. He has successfully integrated and used hand-held GPS technology on his Swarbrick S111, Pastime of Sydney for years.

Last changed: 9^th May 2004