Oh it's not that bad. I think there's a small range of props it needs, depending on the boat you want to run it on. And on the 2 strokes, you can "get away" with a fair bit as well - ie if it's 200rpm over the rev limit at full speed, lightly loaded, that's neither here not there on a 2 stroke.
The issue is that the dealers can use the "tools" they have to look up part numbers and so forth for you - but if you've got an unknown prop on it that they can't cross reference - there's not much more they can help you with. They could spend half a day researching it for you, but on a 22 year old motor, you're not likely to be buying a brand new mercury marine prop from them for it....and even if you did, there's very little margin to them on an item like this. Moreover, the part is also probably NLA from mercury, so they spend all the time for nothing.
You've pretty much got access to all the tools a dealer would have - some people use crowley marine, I use
https://ribsmarineparts.co.uk/
I've probably spent half an hour browsing the parts catalogues for you, on this, myself.
I know one dealer that has a hard limit on the age of engine he'll work on. Solely because if it's older than that, he can be sure that every nut & bolt will be seized and parts will be hard to get. And also, that the customer won't want to pay the time it takes him to carefully drill out and probably have to helicoil all the seized bolts - because if they were happy to pay that kind of labour, their money would like be better spent on a newer motor.
This doesn't mean the older motors aren't worth it - just that they do have a business to run. Both my outboards are 20+ years old. And guess what - doing a water pump on each - had to replace the gearbox on both of them because the bolts were seized so badly they'd cracked the housings! But they're nice motors in good condition (now) and I do all the work myself, so it's fine.
Anyway, it looks to me like you've got an after market prop on it - that complicates things. All my mercury props have what I'd call a "proper" part number on them I can identify. Challenge will be if you can find who it came from.
If you're looking to buy a new prop, try these guys :
https://www.steeldevelopments.net/
They could probably refurb your current prop too, if you wished.
If you're looking for used, keep an eye on ebay. I've actually got 3 props for my boat, in 3 different pitches, to trial each one of them. One is borrowed, the other 2 were ebay specials.
I've run 2 of them (the finest pair), but I need to have a go with the coarsest one at some point.
Seutrek
