You remove the ICM when installing the Mallory or MSD marine distributors.
I am on last line of the Thunderbolt V Ignition troubleshooting chart.
So if new coil doesn't fix ignition problem then next and final step is replace ICM. ICM costs more than either of these distributors so I'll have a decision to make.
I should get the coil and ignition sensor today, hopefully they will fix my spark issue.
2006 Bayliner BR205
A1 Gen 2 1.47
5.0 carb engine