Can someone explain exactly what this is? I have a used Explorer 190 TV with a Bob's Jack Plate and a 140 Nissan with power tilt and trim and a Shallow Blaster cav plate. Sometimes I can get going and others, I kick up a lot of water but can't seem to get going or get on plane. Have the motor trimmed down to get started with the jackplate around 3" but still kick up a big churn but no real forward motion, can't seem to get past 25-30 rpm. I can get the prop all the way down but sometimes it doesn't seem to matter and sometimes I'm just fine. Read something bout "porposing" and wonder what it is and if that's my problem? Any thoughts or ideas? PWC's are doing circles around me!