anytime I enter deeper water about half way up the motor but not to the sparkplug it starts to bogg until it dies I have checked the carb vent by keeping it above water and still the same result. any ideas?

 

I couldn't tell you where to start looking, but it kinda sounds like you are losing your spark or power to the coil.
ATV's people may drive into deep water dose not make them "made" for it per say. Somewhere there is a spot where water is getting and your just losing your electric.
I would look at where the water is getting to and see if below that point if there is bad connections

 

Stop going through deep water. Problem solved.