Yeah you'd think , but thats a nyloc nut and they do work so I guess it comes down to what your used to.
If your going to used nyloc nuts you really should used them once only .
Ha , I have actually been on the lake with a friend fishing and racing our dinghies when I suddenly started winning .....yep , his prop fell off......towed him home with a 2hp Mercury
Mercury 150 EFI. It looks like I have a proper hub kit for it. The nut was loose. Not so the prop rattled but nowhere near the 55.3 lbs feet the book calls for. This boat would have been delivered this way from the store. The same store that I complain about the most.
Mercury manuals all show a tabbed washer arrangement. Every prop and/hub kit I have bought for a 150 Mercury had tabbed washers. I really should call the service manager or store owner and tell them all the crap I find on the boats they deliver. The list is long.
I think they installed prop with a Honda hub Mercury nut.