TOPIC: '03 Merc 25 vs '64 merc 35 hp to hp

We are still in the process of looking for a replacement for my Dad's old 35 on his Herter boat. We are going to look at a 2003 25 EL 2 stroke and I'm wondering about the hp ratings.I'm I correct in thinking the old 35 is crankshaft hp where as the new motors are prop rated? If thats the case they should be pretty close then? Thanks guys.

Yes it should be fairly close I think it's a 15% difference in the way they are rated.The newer one should be a lot tighter,compression and wearage factors playing a big role.Of course this would be based on a ton of hours on the 64 vs the 03. Also if the 64 had the original prop that would make a diff, as the newer ones are more efficent.So it all might add up to "35" vs 30-32 in dog years.

Thanks,I thought they'd be close wasn't sure.We are going to go look at it this weekend and go from there.

We ran a 58 Mark 30 on our Herters Flying Fish until it give out then we put a 66 Merc 500 on it . It flew. I think that would be the perfect Hp. Maybe a 40hp of todays ratings.

Well we ended up getting the 25.Looks like it's brand new,the owner had a pontoon and up graded to a 50. Thanks for the help.