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Old 11-03-2018, 10:46   #16
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Re: Greenland and Iceland Cartography

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Originally Posted by Dockhead View Post
Thank you! I'll look forward to your impressions.
DH- Our trip south has been delayed a few weeks- providing me time to get back to making the comparisons of Navionics and C-Map charts of Iceland we discussed.

I'm embarrased to say I have now discovered that Iceland and Greenland electronic charts were not included with the pile of charts [paper and electronic] and books I obtained from my friends that traveled that route in 2017. [My current electronic chart collection ends halfway to Greenland from Canada...]

However, I still need those charts. Based upon my [previously mentioned] spot comparisons of Navionics and C-Map in the NW Passage [NWP- Canada and Alaska] I can say I am far more comfortable having both [for the NWP portion anyway] to assure the most detail possible of every location we may transit.

Therefore, I am ordering the Navionics charts of Greenland and Iceland now, and will obtain C-Map charts when I get closer to transiting those waters [2019?] The reason I will start with Navionics is they are much easier to keep up to date [and all for a fixed annual cost vs. having to send SD cards back to C-Map annually...] and the Navionics autorouting [we use iPads] is very useful for passage planning.

Since you will be making the trek before me, I would be happy to loan you the Navionics Iceland-Greenland charts card [if this is permissible in license agreement- I have not researched that yet...]

I apologize for not being able to follow-though with my intended comparison at the moment.

I am chagrinned...

Bill
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Old 11-03-2018, 15:10   #17
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Re: Greenland and Iceland Cartography

Quote:
Originally Posted by wrwakefield View Post
DH- Our trip south has been delayed a few weeks- providing me time to get back to making the comparisons of Navionics and C-Map charts of Iceland we discussed.

I'm embarrased to say I have now discovered that Iceland and Greenland electronic charts were not included with the pile of charts [paper and electronic] and books I obtained from my friends that traveled that route in 2017. [My current electronic chart collection ends halfway to Greenland from Canada...]

However, I still need those charts. Based upon my [previously mentioned] spot comparisons of Navionics and C-Map in the NW Passage [NWP- Canada and Alaska] I can say I am far more comfortable having both [for the NWP portion anyway] to assure the most detail possible of every location we may transit.

Therefore, I am ordering the Navionics charts of Greenland and Iceland now, and will obtain C-Map charts when I get closer to transiting those waters [2019?] The reason I will start with Navionics is they are much easier to keep up to date [and all for a fixed annual cost vs. having to send SD cards back to C-Map annually...] and the Navionics autorouting [we use iPads] is very useful for passage planning.

Since you will be making the trek before me, I would be happy to loan you the Navionics Iceland-Greenland charts card [if this is permissible in license agreement- I have not researched that yet...]

I apologize for not being able to follow-though with my intended comparison at the moment.

I am chagrinned...

Bill
Hi Bill:

That sounds like a good approach.

I spent a glorious day in the library of the Cruising Association in London reading everything I could get my hands on and studying different paper charts.

I've come to the conclusion that the charts are of limited value in any case. Since very little hydrography has ever been done and very little continues to be done, I doubt that keeping the charts right up to date is all that important. The charts haven't even had datum errors corrected. That being said, of course, I agree with you about Navionics and "Freshest Data" -- at least you know that you're not sailing around without some great revelation in the charts released last year.

So I think I'm going to make a full set of GE2KAP charts for OpenCPN -- that will at least provide a check on the datum problems.

I would be very grateful for the loan of your card -- thanks for the generous offer. You'll get all of my GE2KAP charts and planning notes as a thank you.

Cheers.
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Old 14-03-2018, 17:28   #18
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Re: Greenland and Iceland Cartography

Quote:
Originally Posted by Dockhead View Post
Hi Bill:

That sounds like a good approach.

I spent a glorious day in the library of the Cruising Association in London reading everything I could get my hands on and studying different paper charts.

I've come to the conclusion that the charts are of limited value in any case. Since very little hydrography has ever been done and very little continues to be done, I doubt that keeping the charts right up to date is all that important. The charts haven't even had datum errors corrected. That being said, of course, I agree with you about Navionics and "Freshest Data" -- at least you know that you're not sailing around without some great revelation in the charts released last year.

So I think I'm going to make a full set of GE2KAP charts for OpenCPN -- that will at least provide a check on the datum problems.

I would be very grateful for the loan of your card -- thanks for the generous offer. You'll get all of my GE2KAP charts and planning notes as a thank you.

Cheers.
Hi DH-

It sounds like we have a solid plan- and I'm getting the better part of the deal... Thank you.

What a glorious day that must have been indeed in the C. A. Library. And your conclusion regarding existing charts matches what I understand from those who have explored before us in the last few years- including the NW Passage.

The need to rely more on other aids to navigation than cartography helped drive our decision to install the [B&G] forward looking SONAR last year as part of our major electronics refit.

With RADAR and now SONAR, we are already familiar with [even confident] identifying spontaneous route changes and investigating possible safe harbors/anchorages. [Coupled with hand held depth sounders as battery powered lead lines- used from kayaks and the dinghy...]

I'll PM you for mailing instructions when the SD card arrives.

Cheers! Bill
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Old 15-03-2018, 03:01   #19
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Re: Greenland and Iceland Cartography

Quote:
Originally Posted by wrwakefield View Post
Hi DH-

It sounds like we have a solid plan- and I'm getting the better part of the deal... Thank you.

What a glorious day that must have been indeed in the C. A. Library. And your conclusion regarding existing charts matches what I understand from those who have explored before us in the last few years- including the NW Passage.

The need to rely more on other aids to navigation than cartography helped drive our decision to install the [B&G] forward looking SONAR last year as part of our major electronics refit.

With RADAR and now SONAR, we are already familiar with [even confident] identifying spontaneous route changes and investigating possible safe harbors/anchorages. [Coupled with hand held depth sounders as battery powered lead lines- used from kayaks and the dinghy...]

I'll PM you for mailing instructions when the SD card arrives.

Cheers! Bill
Fantastic; thank you.

My boat has forward looking sonar which was installed as part of the original build. It's an Echopilot Gold with the big commercial transducer, so similar in performance to the current ones. I think you did right to fit it, but you should be cautious in relying on it -- the range it sees forward is limited inherently to a certain (small) multiple of the water depth, and so it is not at all useful when you are travelling at any speed over a couple of knots. It can be very useful, however, when you are picking your way slowly through an anchorage trying to learn the bottom, or trying to find your way through a tricky pass. I think I will get some use out of it in Greenland, but I'm afraid it is not a panacea or even a major solution to the basic problem.

I think the only way to deal with the uncertainties of poorly surveyed waters such as these are the good old fashioned ways of staying well offshore as much as possible, taking it very slow and very careful whenever you are close to shore, be skeptical about the charts and use the radar and HBC (and GE2Kap charts) to correct the datum and other errors, and avoid doing anything trick on a falling tide.

Your post reminded me of the value of hand held sounders and dinghy surveys -- thanks. I'll put that on my list of gear to acquire. I wonder if there is some efficient way to record the depth data from a dinghy survey, reference it to geo coordinates, and display it on a plotter. This could be really worthwhile, and not only in Greenland - there are places in the Baltic where this could be an extremely useful technique.
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