Is it feasible linking b5Cs with algcom antennas 85km link over water ?
Good idea? Probably not.
With that much water you are going to have issues with thermal inversion. (Basically the water will be a different temperature then the air which can create pockets of warmer/cooler air that refract the signal.)
The preceding issue will be antenna size and alignment. You will have to use massive antennas to have anything reasonable of a signal and aligning those on that distance of a link is not an easy task. Mimosa’s link planner is normally pretty good at estimating the expected throughput, but I would be hesitant to think that you will reliably get that especially if you get really bad storms.
A side note, if you ever need more bandwidth you will be in a bind. Expanding the bandwidth will be very very difficult.
I wouldn’t recommend it, but I know there are people going further.