Wetsuits are only good for warm still water, like scuba diving. Cold water scuba (like 50 degree water in monterrey) requires a min 7mm wetsuit which is too bulky for most boating activities
The theory behind a wetsuit is it allows a thin layer of water between you and the suit, which your body warms. The suit helps trap heat and thickness provides insulation
However, outside of the drink, a wetsuit will get wet and hold a lot of moisture instead of shedding it like a drysuit. Wind will cause evaporation, which loses heat at a rate considerably faster than contact with water alone
This is the reason if you are a diver it is best to get out of your wetsuit asap when you surface
General rule of thumb is to add air temp plus water temp and if its less than 130 degrees F you will need to protect yourself against hypothermia
Hey, if you want me to take a dump in a box and mark it "guaranteed", I will. I got spare time.