Thank you for posting
a fresh version opencpn_4.1.915.apk android. It works well.
I would like to mention that anyone who installed the previous versions, opencpn_4.1.909.apk and before, that these versions might no longer work on your devices. I had the app installed on three different devices and this morning none of them would open. I un-installed and re-installed the 4.1.909.apk to no avail.
It seems that the author(s) are able to access your device and block the app from opening.
I find it morally interesting that someone will use the open source community to obtain money
, help and other forms of support to create an app and then take it for personal profit.