• Joint Warrior Exercise in Scottish waters affects GPS

    If you are on the water between now and 26th April in the Minch or anywhere between Loch Ewe and Cape Wrath be advised: This month's Joint Warrior exercise could see jamming for an hour at a time. In a notice to fishermen, Joint Tactical Exercise Planning Staff (JTEPS) said there was the possibility GPS services could be denied to civilian users for periods between 17-26 April. The jamming would be done around Loch Ewe and Faraid Head in Sutherland and at times that would include from 09.00-10.00 and 19.30-20.30. JTEPS said in its notice that the activity could affect vessels in the Minch and was subject to approval from the Ministry of Defence (MoD). However, it added that prior warnings would be given. Satellite TV, mobile phones and internet connectivity may also be disrupted.

  • Have you tried taking your car satnav for a walk?

    You have driven to an as yet unvisited place. Maybe you leave your car in a Park 'n Ride place on the outskirts, or stick it in a multistorey you just happened to see on the way in. If you remember you load the current location as a favourite in the hope you can find your car later in the day, then you walk off. I find my satnav, a moderately recent but now unsupported Navman, is completely useless at walking pace. It seems to need to be moving at 10mph just to find which way is up. If I have entered a destination I want to visit it is incapable of working out a sensible route as it frequently starts with the impression that we are already going in the opposite direction. I never had this problem with a handheld GPS. My old Garmin 12 could find north if I was crawling on hands and knees. How does your car satnav perform if you take it for a walk?

  • A very brief introduction to chartplotters

    Chart plotters give a visual chart display, and when linked to a GPS will show your position. They can also be used to create waypoints and can be part of an integrated system that will show other data. How they work For yachtsmen with an extensive range of paper charts, the original chart plotter which started the navigation revolution – the Yeoman – might be ideal. It uses paper charts fixed to an electronic board, and as you move the cursor around the board the changing lat and long is displayed on a screen. Plotters with charts stored on cartridges work on the same principle. To create waypoints all you do is zoom in and click the cursor and the lat and long is stored. So to make a route you just drag and click across the chart. This saves all the mistakes of transferring positions from a paper chart into a GPS memory. What to look out for No display is as big as a paper chart and big screens cost more money. For sailors who navigate on paper charts and just use a chart plotter as a ‘visual position reminder’, then a small screen is fine – as long as you are happy zooming in and out. Mono screens used to be easier to read in direct sunlight, but colour screens have improved and make details much clearer. However, do check that small details on the chart are clear, as some screens are quite pixelated. Also check that the symbols are to your liking, because the same chart cartridge in two different makes of chart plotter can create different symbols. The rate at which the charts redraw is worth checking, by scrolling north/south and east/west. Also try zooming in and out quickly. Charts These come in two formats, raster and vector. Raster charts are electronic copies of a paper chart but vector charts are made up of layers which can be turned on and off to make things clearer. If you are not sailing at night, for example, you can switch off all the light symbols for clarity. On some sets the lights that are within range of your position at night will start to flash with the correct characteristics. And if you are using the chart plotter combined with a radar overlay, it is often clearer if the main chart is under the radar image and then there is another layer on top of that, showing just a black coast outline with the navigation marks. Graphics More information is being added to electronic charts all the time – many now have satellite images that can be overlaid on the chart, aerial photographs, 3D displays of land contours that can be viewed from different angles and also 3D views of the sea bed. Obviously the basic charts don’t have all these ‘bells and whistles’ but it is worth comparing the different graphical styles of each cartography manufacturer. Most will only work with one type of cartography and this might influence which plotter you buy. Also check the areas covered by each chart cartridge – some makes might cover your cruising area more economically than others. GPS - What are all these acronyms EGNOS, MSAS and WAAS? They refer to a capability found on higher specification GPS chartplotter units, with each of the three effectively offering the same service in different parts of the world.  EGNOS - European Geostationary Navigation Overlay Service (Western Europe) MSAS - Multi-functional Satellite Augmentation System (Japan and East Asia) WAAS - Wide Area Satellite Augmentation System (North and Central America) These services augment the GPS service in their respective areas by reporting on the accuracy and reliability of the GPS signals and as a result increase the accuracy of compatible receivers from around 15 metres to on average 1 to 2 metres.  Each system is made up of a combination of geostationary satellites and ground stations, and transmits a signal containing information on the reliability and accuracy of the positioning signals sent out by GPS.  These are in turn transmitted to suitably equipped GPS receivers thereby enabling them to display the updated position information.

  • Another new Garmin product.

    Another new product from Garmin is the new GPS 152H high-sensitivity GPS. This quality grayscale GPS fits both your boat and your budget. Mariners will be able to acquire satellite signals quickly and accurately, regardless of their position, thanks to the high sensitivity GPS receiver and WAAS capability. The unit also features a built-in BNC external antenna connector. The increased memory in the GPS 152H allows users to store up to 3,000 waypoints and 50 routes. And, best of all, it’s easy to use!

  • Garmin Product announcement

    Garmin have announced the next generation in marine handhelds: the GPSMAP 78 series. Incorporating a sleek, new design and must-have features, these rugged units are a great fit in Garmin’s best-selling lineup of colour marine handhelds - and they float! Featuring a bright 2.6-inch LCD color display with built-in basemap and high-sensitivity GPS receiver with HotFix®, the GPSMAP 78 series takes recreational navigation to a new level. Both models are waterproof, include a built-in microSD™ card slot for loading additional maps and have a dedicated MOB (man over board) button. In addition to the standard feature set on the GPSMAP 78, the 78s version adds a 3-axis compass, a barometric altimeter and a world wide shaded relief basemap. The GPSMAP 78s also offers wireless route and waypoint sharing with other compatible units. Both units support Garmin Custom Maps and BirdsEye™ Satellite Imagery. Garmin Custom Maps is a free and simple process that transforms paper and electronic maps into downloadable maps for your compatible Garmin GPS. BirdsEye Satellite Imagery is a subscription-based service that allows you to see aerial views of your destination. If you’re looking for the perfect high-performance marine handheld, take your pick from the GPSMAP 78 series.

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