Before K'Gari can go anywhere....

The propellers need to be de bagged.

Far more simple than the bagging process.
Enter the water armed with sharp knife, hold breath, submerge , find the tie , cut, remove and keep a grip on the bag, so it doesn't sink or drift off to join the acres of plastic bags found in the oceans.

https://youtu.be/QR0ZJkc9X78

Intriguingly upon my return, I had noticed the bags appeared to have fostered some marine growth whilst in situ for a couple of months.

I wasn't going to take them off before I was likely to actually want to use the engines, so a quick shot with the go pro, on the good ole selfie stick, (my intrepid adventurer crewman in Vietnam had finally bought one in desperation, once he realised I wouldn't be seen dead with such a device)- so publicly now, yes, I admit it was a brilliant idea- thank you! This is what was revealed via go pro.

https://youtu.be/RvLlC706o1E

And this is what it actually looks like when the bags are off and out of the water. Several kilos of marine growth had moved into the new "des res" afforded by the black plastic bags.

The bags themselves had done the trick, no barnacles or other growth on the props or saildrives.
The only thing to  do now, was remove the build up of what I can only assume is decaying zinc anodes, that had covered the shiny brass props. with a coat of grey.
Many breaths later and with use of trusty scraper and wire brush, the propellers resembled once again the shiny clean objects that had been bagged months before.

Mental note - again, this time remember to  make a written note, to get a hooka or a bottle for underwater work.