I'm amusing you are talking about the engine/shaft coupling removal. The Prop shafts used are double taper shafts. The prop is located on a taper and the coupling is too. The access to the engine coupling is limited by boat design. There are a few ways to get the coupling off. My first attempt would as follows.
Loosen and remove prop nut
**Remove the prop ,this may require a prop puller to "pop" it off the taper
**Reinstall the prop loosely ( don't tighten nut leave loose)
**Remove coupling bolts and slide the coupling to the packing gland
**Remove the nut located in the bore of the coupling ( this may require cutting a socket down for clearance.
**Put a block of wood between the hull and the loosely installed prop with key. This will lock the shaft for loosening the coupling nut.
**Once the nut is loosened and removed. Remove the block of wood and prop. Slide the coupling back to engine coupling and bolt back together snug not tight.
**A slam hammer is needed with an adapter, threaded portion on one side that matches the shaft thread. This may be purchased or made. Many boat yards that have service centers have an assortment of these. The opposite side of the adapter will have a thread size for the slam hammer shaft to thread into.
once the slam hammer is properly assembled to the prop shaft use the slam hammer to "pop the shaft off the taper.
**When the shaft breaks loose of the taper remove the shaft key from the shaft loosen the packing gland all the way for removal and slide the shaft out. There is clearce for the shaft to be removed because of the offset rudder.
If this doesn't work the technician is going to have to be creative. The space is limited but a small puller could be made and used to remove the coupling from the tapered shaft.
Last resort would require destroying the coupling. Using a cutoff tool to cut the coupling off the shaft. This requires a lot of patience and steady work. If this is done make sure there is some type of fire blanket used to cover and protect components in the engine compartment from grinding dust and sparks ( this is the last resort method) If this method is used I would recommend purchasing matching couplings engine and shaft to confirm proper coupling balance.
I was typing this while Mike answered so the post is redundant. I didn't see his post.
