On our recent bought sailboat there is the installation  with the following components:
Alfa apoe03 , tp-link (tl-mr3020) and a ubiquity m5 mini (+ see picture).

I am trying to figure out what all these components exactly are and what they actually do and how they work together.

We have a wifi signal on board called 'tripel wifi' to which some devices are connected  (plotter, cell phones, ...).
When we are in the harbour and there is wifi I go into the local ip of the ubiquity antenna (192.168.10.20) and select the harbour wifi and connect to it. 
This way the devices always have internet via the same network (triple wifi)

I assume the tp-link is a router(?) (switch is set to WISP) which creates the 'tripel wifi'?  
And the ubiquity antenna is in charge of picking up any wifi that is available?
The alfa poe just gives power to the ubuiqity antenna and transfers the 'internet' from the ubuiqity antenna to the tp-link router which then sends it out via the 'tripel wifi'.

Are these assumptions correct?

Now onto what we actually want from the system.  

When in harbour we want to connect to the harbour wifi so that our internal wifi network gets internet via this way.
Or we want to be able to use a sim card for mobile data and also have it broadcasted via our internal wifi network.

With the current setup this can be done by having a mobile phone create a hotspot and have the ubiquity antenna pick up this signal.
But maybe there is a better way to achieve this?