First make sure your bilge pumps are working properly, because it is the prudent thing to do.

Next thing you want to do is to clean the propeller shaft between the shaft seal and where the Spare Seal is sitting.

Remove the 2 (or 4) screws that hold the Spare Seal Carrier in place and set these and the outer carrier shells aside. (Don't lose them, this is reusable)

Make sure the spare seal has been fitted the correct way round on the shaft.

Remove the 5 screws from the face of the shaft seal and slide the cap over the new seal.

Twist the Split Washer and remove from the propeller shaft. Set this aside and do not lose it as it will be reused.

Using a small flat blade screw driver, insert it into the screw driver recess in the shaft seal housing and pry the old seal out. There will be some water coming into the boat but not an excessive amount.

Cut the OLD seal off of the shaft using a pair of side cutters, being careful not to scratch the propeller shaft.

Clean out the Lip Seal pocket area and then slide the new seal into the pocket area and press in place.

Put the Split washer back onto the propeller shaft and seat it inside the cap.

Slide the cap in place, start all of the screws back into the shaft seal. Tighten each in a criss-cross pattern to a maximum of 27 INCH pounds.

This would also be a good time to check your water flow to make sure you are making one gallon (4 litres) per minute at idle.

You can either replace the spare seal carrier on the shaft or put it somewhere where it won't get lost. If you place it back onto the shaft, make sure that there is at least 1" (25mm) of space between it and the shaft seal housing.