Monday, 19 March 2012

Gps , chartplotters ais and more gps & charts open cpn, navionics, garmin

I got a bit carried away on the gps and charts things, When I got the boat all it had was an old raymarine gps plotter, which did not work. I sorted it fairly quickly as all that was faulty was a lack of power due to corroded connections.

It is an old unit , black and white and the charts were only for the British Virgin Islands , not much use to me, the base map was a joke and pretty useless, so its only use would really be to get gps info ,coordinates,speed heading etc, not much use for actual charts.

I decided since it would leave a rather large hole to leave it in place, handy as a back up, Now before I got the boat I had obtained copies of the cm93 maps, from online  ;) and rigged them up in the laptop with a gps dongle, hey presto instant worldwide charts on your laptop. Now I can also take a feed from the standard horizon vhf radio for the ais signal and feed it into the laptop to show ais signatures on open cpn and the cm93 charts

The problem with laptops is power usage, they use lots of it, maybe 4-6 amps, whereas a conventional chartplotter with small screen uses less than an amp, can be seen in daylight and is normally waterproof so can be used outside, Laptops are great for passage planning , but not so great for use on passage, don't get me wrong you can do it, but a dedicated chartplotter would have been nice.

The problem I had with a dedicated one is the price of the charts, for going round the world you are looking at several thousand pounds,an unacceptable price to me, rip off!!

I had a little garmin dakota unit, which I used on my old boat, had a decent base map, but no nautical charts though it could display them. Hunting on the net one day, I found out you can download garmin charts and make them work on your own plotter or gps fairly easily with a small bit of modification. Now the legality of this is iffy, if I was selling them then I'd certainly be breaking the law, but for personal or reference use in a non commercial way, I'm not sure how the law stands. Somehow I doubt garmin are going to sue me and if they tried, I wonder under which jurisdiction, say I only used them 12 miles off shore in international waters?...

Anyways I got some bluecharts onto the little garmin dakota working ok, I had got one of those viewpad android tablet style things, very cheap and works a - treat gps built in and hspda 4g dongle inbuilt for internet, great battery life and easy to carry about. I downloaded the navionics charts onto it, I was quite happy to pay their very reasonable prices, 17 pounds for the Mediterranean vs several hundred pounds for a chip for a plotter (same charts....)

If you were doing everything above board then by far the navionics charts on ipad or android are by far the cheapest way to get global electronic charts, you can also get ais and weather and all sorts on these pads when you are close to the coast through gsm phone/internet.

Now I was not going too bother getting a proper plotter, but since I found I could get the charts online , I bought a little garmin 451 unit. It is great to have a proper dayllight viewable screen and waterproof unit outside at the helm, chartplotters are great and well but useless if you have to run up n down stairs every 5 mins to get a reading.

I linked the litte garmin unit up to the standard horizon 2100 vhf unit I purchased which has ais, so now the ais can be displayed on the garmin, which shows it well,  DSC polling can be done via the garmin and the garmin also sends gps info back down to the vhf which can also display ais /dsc and gps info on it screen.

I wish I had known at the start I could have done this and saved myself a few pounds. I keep bidding on sextants on fleabay, I have no idea how to use one, but hey I have books on celestial navigation and some wide area paper charts, so I am sure I could learn pretty damn quick should the need ever arise. Lets face it barring WW3 or some alien invasion or solar flare I think the sextant will stay in the box, but hey lets prepare for every eventuality.
I really struggled to find a place to mount the garmin unit, it does obscure the tridata but only when seated

The little Garmin gpsmap451 up n running.
The little Garmin Dakota handheld , good little unit, especially now with marine charts ;)
The screen on this viewpad is far larger 7 inch and touch screen, great little unit,  Navionics charts!
If you already have a laptop, this is the real cheap option open cpn software and cm93 charts, Cost= ZERO!
Standard Horizon 2100 VHF with AIS built in, saves having an extra antenna going up.

For the non boaties. GPS is similar to as in car sat navs, AIS is an automatic identification system used by larger vessel which transmits on radio their position and direction/ contact info, DSC is a way to make a VHF radio act kinda like a phone

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Thanks for your interest!

Nic n Steve.