I believe there is a setting option on some transmitters to eliminate the double tap.

On mine I've got to double tap reverse to engage it. Also make sure the trim is set to neutral when switching it on or it won't engage reverse

Hope this helps

Scott

its a marine type ak china version just changed it for a different make still not right

Is this a new transmitter and receiver? I had experience with a new one that was set up as a drone radio. The left throttle switch (does not have a spring to bring it back to center like the throttle stick) on mine transmitter. the one I have would on or on or off for the complete travel of the stick (left stick). What I dis was used the right stick with the springs to bring it back to center). This work around worked👍😊

Good evening Stephen, disconnect the motor and try directly to a battery, if it works in both directions, reconnect with the esc, unplug esc from receiver and either use a servo tester or plug the esc into another channel on the rx and try again if this works then check your connections are clean and put back where they should be.
Hope that is helpful, cheers Colin.

What type of speed control are you using?

I have used some which were made for rc vehicles but not specifically for marine use. Those rc vehicle type required me to double click the reverse toggle lever on my transmitter. Apparently this type of speed control is designed so the transmission in a vehicle goes into “ neutral “ before moving into reverse and damaging gears. I have found these type of speed controls have the similar, when going from reverse to forward. There is a pause.

Best not to use that type of speed control in a boat. Pay the extra money and get one specific for marine use.

My opinion.

Ron 🇨🇦