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Old 21 May 2016, 18:15   #1
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Etrex adventure (basic gps)

So I just ordered an etrex gps, just the basic 10 for 75 it seems a bargain and hopefully will do what I need (basic speed & distance logging, digital compass and headings) basic navigation.

For 75 it seems a good deal and I have found a free and legit source of charts which I am going to have a play with (better than 220 for the Garmin ones)

They are on sale for 75 at maplins and blacks (80 for geocaching bundle at blacks and 5 off ordered over 50 and free delivery over 70)

I was looking for a used one on eBay but got impatient lol......


One info I am hoping is I can set a destination and the he Etrex will display a heading on a 2" arrow I can follow........... If not oh well......(at least I can download my meanderings when I get home)
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Old 21 May 2016, 18:46   #2
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This is the chart resource I am hoping to use

OpenSeaMap and Garmin nautical chart plotter - OpenStreetMap Wiki
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Old 22 May 2016, 01:53   #3
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Good pick with the Garmin - the Navigation function will certainly do what you want and more.

The charts are a joke (they don't show depth or tidal areas?). That said - if you are only using them on familiar waters and you have uploaded waypoints for your main routes and ports then I suppose they have their use.
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Old 22 May 2016, 03:55   #4
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HDAV all the Etrex handhelds are brilliant little devices and despite having the seat mounted 45DV now I'll always keep the Etrex as backup. Their AA batteries last for several days out and a 4 pack of spares means you have enough power to be out for a week. Mine hasn't faulted at all and I've had it years.

Not wanting to add a negative but are you sure the 10 will allow uploading of charts?? Hope it does anyway as it allows future upgrade. Mine came with the Garmin Bluecharts loaded and I have to admit the mapping is one of its greatest features.

Unless in very familiar waters I usually print out the chart area we're operating in (from the Bluechart version on the PC) and run it through the laminator in A4 size and of course I carry a compass.... these are my last ditch backups.

However it's very difficult to navigate by traditional "chart table" methods on a bouncy SIB and that's why for me the mapping Etrex was one of the biggest safety/convenience improvements in smallcraft boating for many years.

Like Willk says if the examples of the open source chart are what you get then they are very very basic. Well worth looking to upgrade to the Bluecharts as soon as you can.
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Old 22 May 2016, 04:37   #5
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You also need to understand how OpenSeaMap was produced.

So OpenSeaMap is produced from the same origins as OpenStreetMap -an open project aimed at mapping all the roads in the world. Idea being people who are interested mapping go out with a GPS and map stuff and upload it. They have in quite a small time achieved a bloody good map for the UK and in doing so have created something that can be updated in relatively quick time when new roads appear. And its "free" as in speech as well as beer... ...so if you wanted to build it into a commercial application if you wanted to (of course your commericial application may not update as often as source maps do!). You can also take the raw data and re-draw it in your own colour scheme etc to suit your own needs, omit layers of data etc.

Open Sea Map has taken that data and is adding 'sea' data to it. **BUT** there are at least two snags you should be aware of:

1. If the data was put on using a GPS to locate the object it could be +/-100m from correct location as they wont be using commercial grade mapping GPSs. It is possible its within 3m, but the risk will always be there. Add to that your own +/-100m error and you can see where the risk can become large...

2. Anyone can edit it. I could edit something in or remove something sat on my sofa never having been there. There are no quality checks on individual edits, instead it is reliant on other map users identifying and reporting errors.

3. There are NO depth data for the vast majority of what you will be looking at. There is world-wide depth data for depths > 100m! It is possible to put depth data into OSM, and crowd sourcing methods are used to do it ... but there is a lack of data and I suspect even when that becomes more populated they will give you lots of data for channels etc but very limited data in the little bays and nooks that Ribbers might want to adventure because it needs someone to have ventured there before you to provide the data.

There are two further errors can arise as a result of this:
- If your sounder is not set up correctly you will mis-record depths, in addition to whatever the inaccuracy of the sounder is anyway. I've certainly known yachties set their sounder to be "slightly deeper" than it really is, to give them a slightly bigger margin of error. Lets face it if your sounder is accurate to +/- 20cm you might tell it its mounted 20cm lower than it really is to reduce the likelihood you'll scuff the bottom. Result - all data submitted is 20cm shallower than it should be. Then heel your boat and it messes it all up
- It needs to relate the measured depth to the chart datum. So it must be using an algorithm to do that from pos & time info. Great. But in some places we know algorithms aren't perfect.

Even with all of that you'll get no bottom substrate info.

I think this stuff has immense potential. Someone like Easdale Harbour Trust for instance can spend a couple of days carefully mapping out the Harbour if they choose. Its then their data, their map to do as they want with. They add a pontoon in the future it can be added for all to see.

It'll be interesting to see if the guys at Antares (Antares Charts ) share any of their data with OpenSeaMap at some stage... they are doing it properly and I have to say in the bits that you might really want to know about a hidden rock etc. Rather than trying to be a free replacement for standard charting they are trying to cover the bits where dragon may still be on standard mapping.
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Old 22 May 2016, 04:56   #6
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I can't see anywhere that says the etrex 10 will display charts, although that doesn't mean it can't. If you need a g2 vision chart though, drop me a pm😎


Sh1t happens
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Old 22 May 2016, 05:35   #7
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I keep an etrex on board as a back up. It is very good when used with the spiders web nav system by this requires a degree of work before you go on the water. I also use one everyday in my work for last fourteen years and in that time two units have failed. I like them
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Old 22 May 2016, 07:42   #8
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Whe your draught is under 2' and yo operate with 20' tides is depth a real issue ? There is a trick to running charts/maps on the 10 it has no sd card slot so you are limited to the internal small memory but if you replace the standard map base map with a specific one you can add data

It's a 2" screen so lots of da will over complicate matters.

All I "need" is a heading either back to where I left from or to where I am going, the mk1 eyeball should do the rest. Trips across the Bristol Channel over round flat holm and steep holm are the plan. Perhaps Lundy.

I also want to some Log trip data and speeds. If the mapping can show dangers (rocks) etc that's great but realistically all I want is an arrow I keep pointing straight to get to destination so if there is a detour I can get back on track easily.

75 for the etrex and some messing about will keep me happy the 45dv will be on the list but not till next year as will need some work to fit and more time and money.....
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Old 22 May 2016, 08:46   #9
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Personally I'd say understanding what is underneath you is important even with a 2' draft. A 20' tide would make me more concerned because rocks which you happily sailed over last week can suddenly be a problem, and with big tides I'd expect overalls etc round headlands, but it depends how complicated your waters are whether you need that plotted in real time.

I think it also depends a bit on whether you work out a clear passage plan before you go, or just head that way until you get fed up...

But don't let anyone tell you that you NEED a plotter, 15 yrs ago very few ribs had a plotter, and 20 yrs ago the majority of ribs didn't even have gps.
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Old 22 May 2016, 09:58   #10
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http://youtu.be/ex7fGF2sXqk

This is what convinced me to go for the Etrex 10 my operational area will be relatively small and if I do venture further (tow to another launch site) then I just need to download and add the relevant area map, the juggling will be the data required vs the space available on the Etrex. It's quite small so high levels of detail won't be available, but I do t feel necessary while knowing what is 30' below is interesting but totally irrelevant also as a pleasure craft under motor I have to give way to everything else on the water and being small it is only sensible too.....for the bits of bay hopping I am hoping to do many will say it's over kill....I know plenty to have done the run purely on the basis of going straight till they see Landon keeping the land on the left there and right back....... Easy when there are big land marks at launch site
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