Very interesting question….I have a ’57 35HP and there is no room at all for this washer. With the prop all the way seated, if I put on this washer, I cannot get the drive pin through. I have numerous props of different pitches, including some that have been professionally re-hubbed…and not one of them will allow for that washer.
I put on the prop, insert the pin, put on the cap and put in the cotter pin….I’ve spent hundreds of boating hours spent that way, no thrust washer.
I can’t say if it’s required or not; I can only say that my engine simply won’t allow for one, and I haven’t suffered at all for the loss…
