@redsox that seems to be an OTG cable. Trees will definitely cut your signal. You need to consider getting higher up to reduce that effect. Rise over run. As for the IMU thing, not sure, was the water rough? Buy a new SD card. (assuming you did a reformat with the spark and its still NFG)
That makes sense, and I'll try that, generally speaking I was flying around the 40-50M height (which is about 15-20m higher than the tree line). The water wasn't rough at all, the boat was obviously still drifting slightly since we weren't anchored but not enough that it should have glitched out the IMU...Lastly, I figured I would have to buy a new SDcard, but I'm worried that a new one won't solve the issue, as the SDcard itself is fine (it works in my computer and camera). What causes an SDcard error with the spark?