Son bought a new Skeeter and I inherited is one year old Ultrex. It is mounted on my older Champion. Marine dealer told him he had to sync his new Ultrex to his hand held fob for his new boat. My question is do I have to sync the fob that came with the trolling motor he gave me?k

If you are talking about the remote that came with the Ultrex from your son, that remote should already be paired with the trolling motor. The Ultrex and the remote do not know it was moved to another boat, and they do not care. The "pairing" is persistent, meaning it remembers even if power gets disconnected. So, once the Ultrex is on your boat, it and the remote should remember each other.

Thanks. Was asking because my so couldn’t remember if he paired the motor & remote. I guess I’ll find out next time on the water.