"Have I inadavertently screwed up the charts by looking at them on the PC?  If so, how?  And can I rescue the situation, or should I just bite the bullet and buy a new card?  Advice please" 

Therotically, you shouldn't have done as you have been using the Navonics charts in a Navonics reader but it sounds like the reader may have corrupted the chart. My first move would be to contact Navonics and don't let them blame your PC.

Cheers

Chas

Of course danger with any card reader is that it works both ways-for example I use a multicard reader to download pics from my digital camera to save on battery power but have it set such that PC arranges to delate pics stored on card  after being read-sounds like something like this might have happened in this case?If I so wish I can upload data  to any card, card  reader is capable of reading including my mobile sim card.

Is the data still available when you put it thru the reader to your PC-if you can see charts OK on your PC then make a copy and check what kind of file it is-right click mouse and click on file/folder properties(sometimes it can give you the file type with in brackets (modified) or similar and a date which would sugest some form of corruption.Check individual map files unopened to see if you can spot any difference as above between various map files.

As to solutions you do need Navionics help-check out their US site- which has lots of help info. available online-may be a known problem requiring a programme patch which you can download onto card. Other thing I note is thataccording to Navionics online compatibility chart Raymarine use a cf chip not sd chip as in sd cards -according to Navionics still compatible with Gold Cards-almost unique in this-all other plotters use an SD chip apart from Northstar.Maybe this has something to do with problem?

Phil

Thanks Chas, and Phil, for your comments. I have looked at the chart files on the PC and they are .nv2 files. All of them say they were created and modified on the same date, in 2007, but that they were last accessed this week (by me). So I can't immediately tell how the card has become corrupted. I do notice that some of the charts seem to have disappeared completely - this is the card for France and Iberia, and all the Portuguese and west Spanish charts have simply disappeared!

I will search my PC for the missing charts, in case they have somehow been installed in a temporary memory somewhere, and removed from the card.

I also noticed that none of the charts are read-only. Shouldn't they be, to prevent this kind of thing happening even by chance?

1)Do above check using following method on PC-click My Computer-shows Drivers usually C,D,E etc-card reader is probably E  or F.This is the most direct link to the card.If it shows missing files as above then would appear they have been delated from card.

2)Using Navionics software on PC can you still see and use maps?-if so they have been saved somewhere on your PC.A good starting place will be where Navionics Software Programme is stored.My Computer,C drive(thats the harddrive),programme files,list of programmes.Find Navionics programme and look manually in all files and subfiles.

Alternatively use search making sure that you search all hidden files and folders-focus only on C drive first.

If they are there you should be able to copy and paste back onto card.

As you can gather had this has happened to me  before but not with something as important/valuable.

Something to be said for a cd where its impossible to delete inf.-BUT suprised that as you suggest info isnt protected in some way?

Phil

Doing any recording to a chart card is a serious risk of corrupting the card. Reason being that you may copy files back to different area of card and still not work, possibly damaging cards overal use.

Chart cards are normally specific to the data on them, copying across to same size card will not work as the encryption / card code is different. It is possible to back-up a chart card to a PC file and in even of card getting damaged later losing data - to restore data back - as it does it to the registered card and in exact same form as original.

Have you tried the card in another plotter or machine other than your PC ?

I would suggest that BEFORE playing with card - get to a Good Navionics Dealer who should check the card for corruption or damage. If you play with card before then they may refuse to correct the card.  Be strong with info that you have not used or played with card outside of recognised designed use. You may be lucky and be rewarded with working card at end of visit !!

Navionics quite openly say that any attempt to even read their CF cards in anything other than their own card reader SHOULD corrupt the data. I have also been told by Navionics that they "wouldn't be surprised" if simply accessing the data through Windows Explorer, even using the Navionics card reader, would corrupt it.  

Small print on the back of each CF card packaging (in bad English!) is the only mention I have been able to find warning users of the drastic impact of doing what comes naturally to most computer literate users - taking a backup copy.

Theoretically, taking an image (ISO) copy of the card shouldn't touch its code - but I have no idea how they have configured the card and am not about to risk £180 finding out. I'm not sure that anybody in Navionics UK has any better idea of how the cards are built.

Whilst it costs £120 to buy a Navionics card reader (with planning software) it is possible to get the same card reader from Raymarine for £52 and download their planning software FREE from their web site. I personally find the Raymarine software much more user-friendly than the Navionics package with a better interface with the CF card.