I'm trying to download ENC's from the government site(s) to my MacBookAir on which OpenCPN version 4.00 is installed. In 2015/2016 I successfully did this and I can open and view those charts. I'm not taking this aboard. I want to study the local waters in my new home waters of St. Lucie River, Indian River and near shore AO. So far I haven't been successful. The first chart I would like is the US3FL30M. I've downloaded it and get a ENC_Root in my download file. Double clicking it opens a screen with 2 txt files (ReadMe & UserAgreement) and a file with the chart name. Double clicking that opens a page of gibberish after the unzipper I downloaded this AM from the Apple Store is done with it. I was offered no choice of where to put the file on my laptop. Should I update the OpenCPN and if so how? Or should I re-start from downloading the current OpenCPN onto a newly liberated PC from my office with Windows7? Or is there a simple fix on my Mac (Which I would rather use).