The high number of snowmobile deaths has the commissioner of the OPP worried.  Vince Hawkes says sledders have to use common sense because the vast majority of the deaths were preventable.  So far this snowmobile season, 18 people have died making it one of the deadliest seasons in years.  Hawkes is normally low-key but the number of deaths has upset him to the point he`s speaking out.  Excessive speed and alcohol are two significant factors that have contributed to snowmobile deaths this year.  Another major factor is people riding over lakes and rivers that are not safe.  In fact 41 percent of snowmobile deaths this season took place on lakes and rivers that seemed frozen but weren`t and the rider fell into the icy water.