Hi there and thanks for accepting on the forum ! Iam totally clueless on this subject and Iam a complete newb !! I have recently bought a motor boat with a yamaha 55 ae outboard but there is a small part missing and concerned that my forthcoming first outing will perhaps damage the motor ! It appears to be some kind of cover to perhaps an inspection or maitainence feature in the lower part of the external prop shaft ! There is one on one side but not one on the other just a view of part of the drive shaft internally and a rubber shocker looking thing !! I could do with posting a photo but not sure how so as I can source and purchase the cover !! I was told that he'd the boat on fresh water but I'm going seaward and by reckoning if it's had one it needs one haha any help will be much appreciated !!