Since I bought my boat a year ago, the first time I go to crank the engine dead cold (not started in a day or two) the first revolution or two of the flywheel is dead slow, almost like I have a dead battery. The voltage on my electronics drops to 9 or so volts. After that first revolution, voltage goes back up to just over 12 and the motor cranks as it should. I have a two battery setup and tested both on a load meter, and know both are charged and are in good shape. This past winter, I rewired the entire boat, so know that all the connections are good and the proper gauge wire was used throughout. Might it be a weak starter motor? I was always under the assumption that if it were a starter issue, it would do it every single time, not just when it was cold.