Very Large scale wgs 84 electronic charts
Using the charts
This section describes some of the more important issues relating to use of our charts and then discusses some of the hardware / software combinations that may be suitable.
Experience: if you are following your position on these very large scale charts you will be close to rocks or other hazards. You should do so only if you have adequate experience: they are definitely not for the novice.
Weather and tidal streams: it is strongly recommended that many of the areas covered should only be explored in settled conditions and at states of the tide when you have full control over the position of your boat.
Tidal height: you will add predicted tidal heights to the depths shown on the chart to decide whether you have adequate water for safe navigation. Tide tables merely predict tidal heights and actual heights may differ significantly. At times of abnormal atmospheric pressure or of strong winds where you are, or in neighbouring areas, you should be particularly careful. It is essential that every time you use one of these charts you check that the actual depth of water is as you would expect as you first enter the area of coverage: if in doubt do not proceed to the more challenging areas.
Using the charts with gps and/or electronic plotters
GPS / plotter set up: it is quite possible to have the wrong settings in your gps or plotter and small discrepancies can become very material when working with these very large scale charts. It is essential that every time you use one of the charts you check that your position is as you would expect as you first enter the area of coverage: if in doubt do not proceed to the more challenging areas. For further information about projections click here.
GPS accuracy, location and delays: remember that your gps gives the location of its antenna. If this is at the stern of the boat it may be 10m or more from the bow. It may also only be accurate to within +/- 10m so that the actual position of your bow may be 20m from the position shown by the gps. Potentially even more significant is the tendency of your position, as shown on a plotter, to lag slightly behind your actual position as you move through the water, particularly if high features on the shoreline obscure some of the satellites. This issue is reduced by keeping your speed to the minimum consistent with retaining control. Taking all these factors together you can be a surprisingly long way from the position shown on your plotter, particularly in the direction of travel; distances that can be very significant in the context of these charts.
GPS loss of fix: in extreme cases, typically in mountainous areas, your gps may lose its fix altogether so you should never rely on electronic charts to the exclusion of other forms of pilotage.
GPS freeze: many GPS devices with USB connections for use with PCs are optimised for use in cars. No driver wants to be told he is creeping forwards when he is actually sitting at traffic lights with the brake on. It is therefore common for such GPSs to be modified to show zero speed or movement of position if the reported speed is very slow, perhaps less than 0.5mph. Fine in a car but not so good if you are in your boat and being ultra cautious. This has happened to us a number of times—BEWARE! It is only when you speed up that it recovers the correct position...which can by then be a long way from where you thought you were... We have bought but not yet tested a GlobalSat BU-353 waterproof GPS (Amazon c.£25) that claims not to freeze at slow speed.
Which electronic plotters?
You can view the charts at home using any PC or Mac with ordinary picture/photo viewing software. You can also use Google Earth. But if you want to monitor your position on them when at sea please read on...
Afloat, the best setup is a PC or Mac with external GPS on the chart table and an iPad* or Android tablet in a waterproof case for the cockpit, all running Memory-Map software. (*iPads should be Cellular/3G to have an internal GPS)
Listed below are some of the hardware / software combinations we are aware of but this is a very fast moving area and the list is certainly not complete. There is not yet a weatherproof fixed cockpit plotter from one of the major manufacturers that will run the charts but we don’t see this as a problem. You can use your main plotter to get you to one of our locations and to keep track of your position whilst there: once in sheltered water use a secondary device to run our charts to help with the trickier bits.
If you are considering software not mentioned below you should check that it will run raster charts in GeoTiff, BSB (there are many versions of BSB so ours may not be compatible) or KMZ formats. Cockpit plotters generally run vector charts, which are not compatible.
Principal Hardware / Software Combinations are listed below. Setup guidance is included with our chart package.
Key: ** recommended * tested with our charts + not tested with our charts. M apps for mobile devices available.
PC**. A standard laptop or tablet PC running Windows XP or Windows 7 or 8. An old one should be fine, especially if you ‘uninstall’ a lot of the unwanted software and delete as much ‘rubbish’ from the hard drive as possible. Maplin do excellent ’Car Laptop Adaptors’ for powering PCs from 12v batteries via cigarette lighter sockets: these use much less power than an inverter and mains power supply and are ideal for boats.
Couple a PC with good software and we believe this offers the greatest flexibility and range of features, although it is less rugged and cockpit-friendly than other options. Compatible software includes:
· Memory Map**M. This excellent software produces a high-quality image and also runs the charts on the main mobile platforms (Apple and Android). For £50 you get the Memory-Map version of the UKHO charts for UK and Ireland. You can also run the M-M UKHO and our charts seamlessly on mobile devices such as iPads or Android tablets or phones for no extra charge.
· SeaClear*. This is free downloadable software, although the quality of the graphics is not as good as Memory Map’s in our opinion.
· OpenCPN*. Also free downloadable software.
· Global Mapper**. The ’Trial’ version is free and is a good plotting package: it is what we use for our draft charts. The ’trial’ is unlimited and does not expire: you only need the paid-for features if you are going to make charts!
· OziExplorer+. Well established software available at modest cost.
· Polar Navy*M. We don’t know much about this product but it has been mentioned to us. It has apps for mobile devices.
Mac. The choice of software is more limited. We have not tested any Mac software and can’t vouch for its suitability but the two listed below look as if they should work,. And users have reported favourably. An alternative is to use a PC emulation package such as Parallels or Bootcamp and then use one of the PC software packages described above.
· GPSNavX+. Users report that our charts work well with this software and that it runs UKHO charts.
· OpenCPN+ although we have only tested the PC version
· Polar Navy+. We don’t know much about this product but it has been mentioned to us.
iPads**(only Cellular/3/4G versions have GPS), iPhones**, Android tablets** and Android phones**. These sound unlikely candidates but in our view are excellent and, when used in an inexpensive waterproof see-through plastic case, offer the best cockpit friendly option. We have used an iPad in a wide range of conditions, including in an open boat in rough weather with spray everywhere: it worked perfectly, although a £200 android tablet would probably have been just as good!
· Memory Map**. Once again, this software is excellent for all these devices although not quite as versatile as when used in a PC. You can run the M-M version of the UKHO charts and our charts seamlessly on all these devices. To do so you will need the Memory Map app for the device (free for Android and 69 pence for iPad and iPhone) and must ‘Activate’ our charts using the code we provide.
· OziExplorer+. They claim now to have apps for these devices although we have no experience of them.
· Polar Navy+. Their website claims to have apps for iPhones and iPads but we have no experience of them.
Garmin handheld GPS plotters. Garmin has greatly increased the range of its handheld products that will run ‘Custom Maps’. We have used the Oregon 450 and while it is OK as a back-up it is, in our view, nowhere near as good as an ordinary smartphone in a waterproof case (see above). The following are believed to be suitable but are all very slow and cumbersome when used with our charts:
Memory Map Adventurer range of handheld portable devices. We have not tried these but running the Memory Map software and being waterproof and rugged they will probably be excellent.
External GPS. One of these will be necessary if you are using a PC or Mac: other devices should have internal GPSs - but do check before buying! There are many USB GPS devices available from about £10 - do a Google search for mail order sources. It need not be waterproof as you can always put it in a plastic bag. You may want a USB extension lead to ensure you can place the GPS where it will get a good signal. Click here for set-up guidance. And do be aware of the tendency to freeze at very low speeds - see Using the Charts.
Setup guidance for the more popular options is included with our chart package.
Duplicate your plotters for safety
If you like following your position on our charts you may wish to build in some resilience; PCs can go into screensaver mode at just the wrong moment or handheld GPS can run out of battery. When we use our charts we always do so with two machines running: typically a PC and an iPad.
Other help and hardware supply: one of our users recommended LondonChartPlotters as a source of inexpensive hardware and plotting software. We have no first-hand experience of their service but they are aware of our charts and may be able to help.
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