I’ve heard that too, but haven’t had any problems getting my ‘56 to go. It runs about 25 on a 13’ duranautic with a speed prop and about 22 with the stock prop. I did run against a ‘53 on a 12 foot aluminum boat a few years ago. He was a little quicker but not much and my boat is heavier. Funny thing is he was so proud because he thought he was beating an 18, wasn’t so thrilled when I told him my was 15 also. I was told the big difference is that the ‘56 and later have a muffled exhaust and there is some restriction. I’d like to get and earlier one myself someday and do a better comparison on the same boat. Until then, there all a great motor based on the same good design.

When I was 12 years old, I used to ski double with my next door neighbor behind a 1958 18 HP on a model F ALumacraft (rated for 16 HP), with the driver sitting in the middle seat with a mid-deck and steering wheel. It pulled us both up on skis out of the water. Another neighbor pulled a lot of skiers one at a time with a 1955 15 on a model F with the driver at the front seat/front deck – I don’t remember if he ever pulled two. His brother-in-law pulled skiers all the time with an 18 HP Mark25 on a model F, driven from the tiller. The 15 and 28 OMCs had more low end torque for gettin’ the skiers up, while the Mark25 had more top end once the skier was up. The good old days when salesmen didn’t tell people they needed 100 HP+ to pull one skier. This was all usually done with one person in the boat – still legal now on most lakes in Minnesota if you have a mirror.
Dave