C Maps Marine Navigation

You perhaps also need to understand that only WiFi+Cellular models of iPad have GNSS/GPS capabilities - this being a function of the iPad Cellular chipset.  WiFi Only models of iPad have no GPS capabilities with which iPad Location Services can derive location.

This fundamental difference may significantly impact your ability to use mapping Apps - in particular if real-time positioning (e.g., a moving map) is required.

WiFi Only iPad models can only “infer” their location from a database lookup of neighbouring WiFi networks for which the geographic location is known, or the geographic location of your public IP address. For static applications in urban locations, where the location of IP public IP addresses and WiFi networks are known, an “inferred” location can be relatively accurate. However, in rural locations, or when using a Cellular/Satellite/VPN connection, location accuracy of an inferred location [if it works at all] may be very inaccurate. 

All this has significant implications for non-static mapping applications. If you need to have moving maps, or have future flexibility to do so, you may need to consider a WiFi+Cellular model of iPad. Choosing a cellular model does not commit you to adding a cellular service plan for the iPad, but ensures that you have immediate access to GPS/GNSS positioning services.

As is, assuming that you actually have a WiFi Only iPad, your available options are:

• Substitute your WiFi Only iPad for a WiFi+Cellular model; this does not commit you to provisioning Cellular service for your iPad, but does provide the needed GPS functionality for the iPad.
• Add an external GPS receiver to your WiFi Only iPad. These are often used in marine, aviation and vehicular applications - and can be either directly connected via Lightning or via Bluetooth. Their are various third-party manufacturers, of which two are BadElf and Garmin Glo.