Saving Old Seagulls

Hi folks - can you help me with a little (or Big Prob) - my 40 plus was working well when all of a sudden it went into big revs, poured black water out of the previously clean cooling stream and promptly stalled. I shut down all systems and then a few minutes later decided to give it a start in the hope that 'it might have sorted itself out'. Nothing doing, just big revs, lots of bubbles, but no thrust - I am not an engineer - where should I start?

So to be clear, one moment situation normal and the next no drive and dirty cooling water.
Sounds like you have a broken drive shaft. Thats the square tube inside the smaller down tube. The crud in the water is from the inside of the decomposed drive shaft. First check that the prop rotates without the engine turning and then the other way round. IE motor turns without prop turning.
Next step drop the gearbox and dig out the remains of the drive shaft and replace it. Not too big a job if it all comes apart.
regards
Phil

Prop spring?....and
does the prop shaft turn?

thanks guys, its a start....what the best way of loosening the bolts to get the gearbox off?

I'd put lubricating spray on first - don't know what brands you have over there - WD40 or preferably Inox over here. My husband didn't have any trouble getting ours off after spraying.

Good luck, Eleanor