I have a PtP link between Oil Rig (fixed) and FSO tanker (float and anchorage ship) made by 2 C5c radio, 20.5dBi assymetrical horn antenna(at oil rig side) and 10dBi omni antenna(on top of FSO pole). The distance of this link is 2.5km. the height of the antenna is 45mtr(oil rig) and 41mtr(FSO)-fluctuate. For certain time the signal for this link become unstable and lost. Does anyone have an advice for this problem?