850 Thunderbolt Prop HP??

[PartyTyme]

Hey everyone, Im fairly new to the forum, and greatly appreciative of the site I have found ALOT of useful information while putting together a lil bass boat. However, there is one thing I was unable to find. I am aware that outboard companies changed the rating outboard from the powerhead to the prop. Therefore, I have a '76 85hp Merc. and was wondering what the equivalent hp would be since it was probably rated on powerhead HP what would the Prop HP be? Any info. would be appreciated. Thanks

 

[emckelvy]

Re: 850 Thunderbolt Prop HP??

The last version of that motor, produced in the mid-80's, was a prop-rated 75hp. So it's not unreasonable to figure that yours is fairly close to that rating.

Ballpark figure would be to subtract around 10 percent in the conversion from crankshaft-rated to prop-rated, but it's gonna vary from model-to-model.

HTH.........ed

 

[PartyTyme]

Re: 850 Thunderbolt Prop HP??

Thanks! I appreciate the info.