HP ratings

Anyone recall what yr they stop rating at the flywheel and started rating at the prop?

No recollection, but I got curious and found that it changed in mid-1980's. It looks like the industry standard was actually revised in 1983, but how long after that it took to adopt the change I don't know.

What I really wondered was how significant the difference would be. In one comment I found it said 50 at the powerhead would be 40 at the prop. I was surprised the difference was that much.

But I'm just reporting from google. Hopefully someone with more knowledge will chip in.

85. I know the Johnson/Evinrude 35 was there in 84 but became the 30 in 85. The 20 wasn't there in 84 but was in 85.


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Yeah, somewhere around 84-85.

Power loss due to powertrain is usually 10-15% depending on engine size.

I think it was 1986 for Mercury? The 50 turned into a 45hp known as the "Classic 50"