We have developed two styles of navigation for our web app at GreenMap.org
Originally we employed a tabbar style to make the web app function like a native app. However, it is a little bit buggy and takes up some valuable screen real estate with the safari bars being permanent. We also tried and interesting employ when turning the app with the tabbar.

Our other version is a hidden navigation that allows for more flexibility and screen viewing but I wonder if it will be intuitive enough for noobs (as much of our user base may turn out to be)

Please check out both versions on you device and let me know what you think!

Fix Positioning OGM Test - tabbar style
Navigation Menu Test - hidden navigation

Thanks for your input