MilliPut
Hi ed, Milliput is a 2 part epoxy filler, mix it carefully, no streaks, and a uniform colour, put it round the shaft on the inside and out, flair it into the right shape, don't leave it to thick, remember it will need to be sanded down, if needs be add another layer. Drys hard so is good and firm when you run the boat, just remembered roughen the edges around the hole just gives the filler a slight key,
You mention prop exits, do you meen the tube leaving the hull (see above) if its the shaft, use a little light oil in the tube as lube as well as a sealant, top up after every sailing.
Mark
Etherow Model Boat Club