Excessive exhaust/Exhaust rolling into the cockpit

[JetTech72]

If the measured CO @ the transom was measured being within good level, than I would think this is only steam coming out the exhaust outlet.
Do you have catalytic converter exhaust on your boat? Those exhaust system tends to run hotter and create more steam during the cooling process.
Just a thought

 

[ScarabMike]

@JetTech72 100% in agreement!