Use The 3:1 Rule
When using dodgers and flies for offshore salmon, leaders that are three times the length of the dodger are a good starting point.
Leader length can be critical when trolling for salmon with flashers or dodgers.
I like to start with a 3:1 ratio based on the size of the dodger I’m using. For example, if I’m fishing a fly behind an eight-inch dodger, then I’ll want my leader to be 24 inches long. A 10-inch dodger would call for a 30-inch leader, while a smaller six-inch dodger would only need an 18-inch leader.
The 3:1 ratio won’t always be exactly what the fish want, but it’s always a good starting point. If you pre-tie several flies on leaders of varying lengths, it’s easy to switch things up and experiment. I like to use 40-pound mono for leaders, as it stands up better to sharp teeth.