Electronic charts for south pacific

[Dave852]

Originally Posted by Muckle Flugga

You may have misunderstood. There are many areas in FP where there is simply no detailed hydrographic information available. So it is not 90 percent wrong in the Tuamotus, so much as 90 percent not covered at all.

Ok I can agree with that.


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[RaymondR]

‘Structural engineering is the art of modeling materials we do not wholly understand into shapes we cannot precisely analyse as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance.

The problem is always the assumed exponent?

[mekeia]

Thank you everyone for responding to my query some time ago. I've been offline doing some travelling. Looks like Navionics is one way to go and I appreciate the suggestion of replacing the Garmin- I think it's a good idea to consider since it seems like it's not going to be much help otherwise.

[chouliha]

Originally Posted by Paul L

The Google Earth images are decent enough to verify that your chart datum is correct and to see the edges of the passes in the Tuamotus. It isn't going to help you navigate through the majority of the atoll that is uncharted and filled with coral heads. These need eye-ball navigation to safely move through. The atolls are large, like 15 x 25 miles, of which only small portions of the passes and the area up to the initial town is usually charted.

Can't say for certain about Tuamotus but in the Marquesas we have been using INavX on the ipad with excellent results. But we most often use the GE2kap GE chartlets we made using Phils's fantastic program GE2kap. Even in bays on the north and west side of Nuka Hiva that are not charted we have been able to comfortably go in using Opencpn and GE chartlets. We rely more and more on the GE charts getting into poorly charted areas.

We have CMap on the chart plotter, iNavX on the iPad and openCPN using GE charts. Plus the ole eyeball as first choice. Second choice when the charts are poor we use GE charts with OpenCPn.

Good luck

Chuck
Jacaranda
Nuka Hiva, Marquesas


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[Livia]

Originally Posted by Paul L

The Google Earth images are decent enough to verify that your chart datum is correct and to see the edges of the passes in the Tuamotus. It isn't going to help you navigate through the majority of the atoll that is uncharted and filled with coral heads. These need eye-ball navigation to safely move through. The atolls are large, like 15 x 25 miles, of which only small portions of the passes and the area up to the initial town is usually charted.

I disagree with you Paul. We find that the satellite imagery is startlingly good in the uncharted areas of most atolls for reef identification until you get into the most shallow areas within the anchorage. Even then, we use satellite imagery to identify large patches of sand where we might choose to anchor.

Of course, you should always use your eyeballs (for many reasons, including a blip in your GPS signal), but we find that most of the time we *could* have used the satellite imagery (we use SASPlanet) for our sole navigation. In a desperate situation in an anchorage if we *had* to move to the otherside of the atoll for safety, we would consider using our cached imagery.

Here is an example of how we've used SASPlanet split screened with OpenCPN in the Gambiers.

Electronic charting on Estrellita: SAS Planet & OpenCPN | Estrellita 5.10b

Also, Navionics were almost always the most accurate in each country we have visited through New Caledonia -- when compared with not-new Garmin and not-new CMAP charts.

[Paul L]

Originally Posted by Livia

I disagree with you Paul. We find that the satellite imagery is startlingly good in the uncharted areas of most atolls for reef identification until you get into the most shallow areas within the anchorage. Even then, we use satellite imagery to identify large patches of sand where we might choose to anchor.

Of course, you should always use your eyeballs (for many reasons, including a blip in your GPS signal), but we find that most of the time we *could* have used the satellite imagery (we use SASPlanet) for our sole navigation. In a desperate situation in an anchorage if we *had* to move to the otherside of the atoll for safety, we would consider using our cached imagery.

Here is an example of how we've used SASPlanet split screened with OpenCPN in the Gambiers.

Electronic charting on Estrellita: SAS Planet & OpenCPN | Estrellita 5.10b

Also, Navionics were almost always the most accurate in each country we have visited through New Caledonia -- when compared with not-new Garmin and not-new CMAP charts.

To each navigator their own The GE images I had for Raroia and Taehauta(sp) had enough clouds in them that crossing the lagoons really did take decent light and a good lookout.

[Livia]

Originally Posted by Paul L

To each navigator their own The GE images I had for Raroia and Taehauta(sp) had enough clouds in them that crossing the lagoons really did take decent light and a good lookout.

Makes sense. I wouldnt move around with those either! And we always waited for good light for our first transit too. Sometimes the light changes midway though so it is good to have all of the possible tools available.

With SASPlanet I can choose my image provider so if Google has a cloud on their cached image I can try Bing for example. Also, the level of zoom available makes a big difference in how detailed and thus useful they are

[rnjpinz]

We just made the crossing this year from Panama While we have a Garmin 4212 at the helm, we double check everything with Google Earth images layed on OpenCPN. One of the boats we have traveled with since Columbia uses nothing but OpenCPN with Google Earth image overlays. You are doing it right. Do your homework well in advance. The Compendium is a great source for information
also.

Bob

[chouliha]

Originally Posted by Paul L

To each navigator their own The GE images I had for Raroia and Taehauta(sp) had enough clouds in them that crossing the lagoons really did take decent light and a good lookout.

Usually by going back a few generations on that particular location in GE you can usually get a clear shot. For example Raroia has 4 versions of google earth shots.

In GE click view then historical data to view previous shots. They are dated as well.

Decent light and a good lookout are paramount but GE is the next best thing



www.jacarandajourney.com

[svseawitch]

We spent 2 seasons cruising in French Polynesia and other South Pacific areas : Fiji, Vanuatu, New Caledonia, Tonga,

This was at the very beginning of electronica charts so we went with PAPER Charts. We always looked at the "last surveyed date". Very scary. Many of the surveys were done more than 50 to 60 years before the charts were printed. Electronic charts are only as good as the currency of the survey.

Most of the boats we travelled with had someone in the rigging for areas that weren't recently surveyed. Some had various versions of a crows nest. The "classic" boats had Ratlines. We used a variation of this and build "Rat Bars". Bought some inch and a half round dowels at the hardware store and lasted them up the starboard intermediate stays. We spent a LOT of time up there and don't regret the effort. In areas with coral the charts were not going to keep us safe.

[savoir]

Oh well that explains it. You were using the updated and revised version. My charts of the Torres area were prepared for the French navy in 1895. They were more accurate than C Map which had me anchored on top of a hill. Made me look though.