Please Help - Outboard problem

[Coodgee]

Guys, I'm up in The Daintree at my mum and dad's new property. He's just bought a second hand 4m tinny with a 15hp 2-stroke Yamaha. We took it out for the first time today and everything was fine - the boat was cruising along nicely. Then all of a sudden we lost most of the drive from the outboard. It still propels the boat forward really slowly at low revs, but if you apply throttle it doesn't really go any faster, but revs quite hard. We had to putt back to the ramp - it took about 30 minutes to go 500metres to 1km. Every time we try to rev the engine it goes a little bit faster but not much - the power from the engine is not getting down to the prop to propell the boat forward it seems.

Does anyone have any ideas of what might be wrong? Any help would be appreciated because this was supposed to be a great holiday :(

[STUIE63]

sounds to me like a prop bush has gone get a bit of paint and mark the prop and the rubber in between the spline and the inside of the prop take it for another little run . if the two marks don't line up the this is your problem and it is easily fixed just take the prop to your dealer and he can fit a new bush you don't need a new prop unless yours is badly worn
Stuie

[FNQCairns]

X2 on the prop bush, consider taking this opportunity to drop down a pitch or 2 for the new prop with of coarse the option to take it back but I don't think you will, 2 up in a 4m tinny and a 15hp engine with most likely the original spec prop on it.

cheers fnq