I'll park this here for anybody that is interested and report back at some point in the future my findings.

I started an experiment a while back to see which was the more reliable communication method especially with model submarines.

The kit - 459 MHz packet radio / 459 Mhz LoRa / 459 Mhz openLRS / 868 Mhz packet radio - I have a homebrew 40 Mhz digital radio but it seems to have a mind of it's own so I have excluded it from this exercise.

I have several ideas on the antenna options. I have been playing with bits of string and wire for antennas for 40 years...

I will get the kit fired up and then once I have them all communicating I can start to play. The good news with these radio's is they all have an RSSI (Received Signal Strength Indicator) as part of the firmware which you can either read and store locally for analysis or send back as telemetry so there is an easy way to "scientifically" benchmark performance

I'll publish my findings assuming I don't loose it at the bottom of the lake...

Jonathan