Fixed GPS

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the way i read it, the accuracy is only 10m (and that for only part of the time) if you are comparing successive readings from the same gps. in real life, you have to add on the accuracy of the chart (up to 150m round the UK depending on location), variations if your chart has a different datum to your gps, errors due to non ideal positions of satellites at a particular time, and even the inaccuracy due to the width of your pencil line when plotting (say 50m on a 1:75000 chart).

maybe all these wont be there all the time, and maybe they wont all add up, but it seems to me that the 10m is theoretical rather than practical. its probably still nearer 100m in practise.
 

VMALLOWS

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9 Oct 2001
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I have a 128 and am very pleased with it. However based on the specs I've seen would go for the 152 if buying today.........if only for the alarm-clock function! (something I miss from the old DECCA, and have moaned about to Garmin.......I often find I've nothing with an alarm on the boat, usually when I need to catch a tide).

Dont know if it's changed on the 152, but I do find the 6 character name field for waypoints restricting. Ideally would prefer numeric/apha keypad, but it seems MLR is the only one to offer it.

A few weeks ago came from Chichester Hbr right up Southampton Water in <50m fog on the GPS, so not complaining on accuracy.
 

pvb

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GPS152 waypoints...

I believe the 152 offers 10-character alphanumeric waypoints. Totally agree about the limitation of 6 characters on older Garmins.
 

duncan

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I beg to differ
in my experience , based on fixed lumps that have been charted like wharves and large pillings on the medway thames and solent, things like the forts in the solent and , say Yarmouth pier, you can take the boat/unit right up to these items and the accuracy with DGPS on is effectively exact - less than the beam of my boat. With the beacon receiver off you do get a degree of variation/inaccuracy but it is normally within the lenght of my boat - around 8m.
Would I put my life on it - no of course not; and most of the things you are going to hit in bad visability are not fixed anyway, and this includes Buoys as well as boats of course!
It is however reassuring that if all else fails it is more likely to be right than wrong.
 
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