We were coming across the lake Saturday afternoon and a pretty odd thing begans happening. While doing about 3k rpms we start slowly slowing down. At frist I didn't really even notice it till I realize I'm add throttle and the rpm's are climbing but the speed is not.
At about 3500 rpm's and the speed is down to about 22 mph, I see the rpm's drop about 4 or 500 and the speed increases to 30 or so. Its almost like the prop was slipping then not???? As if there is air around the prop and then it goes away and all is back to normal except in a few mins it does it again.
The sound of the engine "seems" louder during the "slipping" time and normal when the speed picks back up?