eveinrude 50 no propulsion

[bash62]

was on the water and on the plane when the engine cut momentarily twice ...dropped revs down and was fine for about ten minutes then just started reving highly like in neutral but stopped going forward .....goes in forward and reverse ...kept the revs very low and got back in at 2 knots but soon as revved it nothing..gradually got worse untill had no propulsion in forward or reverse...any info would be much appreciated
cheers
bash

[bash62]

ah i think its the drive bush cos put boat in gear and try to rotate prop and it turns easily ..took prop off put nut back on and turn shaft with a socket was very hard and could hear engine turning over