Normally it has a lot to do with transducer placement, I know mine’s not perfect, and I too cut out at “high speed” until I noticed on day it wasn’t do that anymore, further inspection revealed that my transducer mounting plate had come loose. Sometimes you can get a little pocket of air under the transducer, sometimes it’s as simple as shifting it a bit.
Am I understanding that you guys are able to get readings on your X102c’s at higher speeds? If so I’ll write off last year as a practice year. I’ve got alot of strakes under my boat. They’re about 6″ apart along the bottom. Maybe I’m getting air. My 102 goes out at about 1/3 throttle and it’s only a 25 hp.
I have no trouble reading bottom with my 102c at top speed, which in my boat is only 44 mph. Not sure how much faster you can go and still read, but I know you can at least go 44.