I'm trying to figure out if I can switch my captains call to when the power is off it runs through the hull. Currently with the power switch off it runs the exhaust through the prop. I rarely use the captains call and at low Rpms with the stereo on it puts a drain on my charging system. Currently have 4 wire captains call

You will probably have to modify it so that when the solenoid is not activated, it is in the open position. Might have to change the brackets around to accomplish this. A picture of the diverters would help. Some of them come from the factory with the opposite arrangement. Just make sure your tips have flappers in them to prevent waves from pushing water up the exhaust.