Garmin on 2500

[Fisherman]

Mine doesn’t read at high speed. I have the thru hull for high speed, but when going above 42 mph , it doesn’t read botton

 

is this normal for all units or do I need a special set up ?

[FINCHASER]

pretty much the norm and not a Garmin thing for sure.  Happens on mine as well... at what speed it loses it really dependent on sea state but is pretty stable to 4o mph.  To minimize the loss use the trim tabs to get the forward section of boat down in the water and IVe found its also more apt to lose bottom if the unit is running in CHIRP mode, I manually select the highest frequency available for my transducer (200khz) Higher frequency is best for bottom read.... whats the frequency range of yours?

[Tall Tails]

Having the transducer forward of the first step allows air to get under the transducer pretty easily. The faster you go, especially in a chop, the easier it is for air to get in there and interfere with the transducer. 

 

[Bamaskeet]

I have a Simrad and a B160, transducer and I read at all speeds.

[Chitwood21MA]

The best luck I’ve had is put it on the “running” factory preset, slow down to 20-30 depending on seas, & if I mark something at that speed when I turn around and get on top it’s pretty significant. 90% of the time I’m offshore I never make it to my number because I find something else while running to it.

Another tip, use your tabs & keep the bow down