I’m installing a Max BR1 MK2 with a maritime 20G on a 40 foot sail boat. I’m trying to place the antenna in a location that’s a little more accessible than up the top of the mast. When placed at a lower level like on top of the Bimini or even off the back rail, how effective does it become?
The 20G is a solid antenna with great performance so I would just give it a go and see how it works. You can always raise it later if needed.
Doug from Onboard Wireless has a good article on this and if you scroll down he talks about location:
https://onboardwireless.com/Choosing-antennas-for-your-connectivity-solution_b_8.html