Scale problems between Admiralty Charts and Arcmap 10

[NicolasChopin]

Hi,

I have a little scale problem with my Admiralty charts on ArcMap10. The data displayed (background map, the shapefiles, etc.) looks right but when measuring it, it is double the size as normal (i.e. an area which is 26 hectares normally is measured as 69 hectares!!!!which is actually more than twice the size...). The charts I use work fine with Arcmap 9.3. Ther is no coordinate system conflict (same between created files and background maps). It could be a compatibility problem between Arc 10 and Arcs for GIS. Anybody ever encounter that problem? Maybe has a solution?
Thanks

[NancyEl-Zeaiter]

Please check your reference scale setting in the Data Frame properties to see that this is set properly for displaying your data.

[NancyEl-Zeaiter]

Also if you can check out this Blog:

The coordinate system you are using when measuring can skew the results based on where the measurement is taken:

http://blogs.esri.com/Dev/blogs/arcgisserver/archive/2010/03/05/Measuring-distances-and-areas-when-y...

[NicolasChopin]

Thanks a lot for that. I will check that out tomorrow.

[NicolasChopin]

I try to change the reference scale: still the same problem, all my shapefiles are too long (measurement wise).  A colleague who has the same charts but on Arcmap 9.3, doesn't have that problem and same for me when I was on 9.3. I contacted the company who provide the charts to check on their side.

[NancyEl-Zeaiter]

Admiralty charts �?? do you mean HCRF?  If so, that is a 3rd party extension that reads the files into ArcMap. 

Do you have the Esri Nautical Solution installed?