1988 Merc 60 hp rating question

[AEROCOOK]

I have a 1988 60hp 3 cyl merc which as I understand would be 60hp at the prop for this model year.
Can anyone tell me when Merc started rating at the prop on 3 cyl models?
Also what would 60 prop rated hp = in the older crank rated models?
I am selling this motor and a guy is mildly interested as he needs to replace his blown up 1970s Merc 70 hp.
Im trying to convince him that a 60hp of late 80s vintage would be = in actual power to his old 70 hp.
Am I far off the mark here?

 

[Dunaruna]

Re: 1988 Merc 60 hp rating question

Prop rating started around the mid eighties. Anywhere from 5 to 15% gain from crank to prop. You are not far off the mark.

 

[AEROCOOK]

Re: 1988 Merc 60 hp rating question

Thanks for the confirmation Dunaruna.