Back in the day English coal mines seeped water into the coal mine shafts. They used horses the pull the coal and water out. It was determined a good horse could pull 33,000 pounds of coal or water out of the shaft. When steam engines started to take over they were rated on how many horses they could replace. Hence the term "Horse Power." Steam engines could be figured mathematically by knowing the working steam pressure, area of the piston and length of the crank arm. Gasoline engines were more complicated. They found that adding a wheel to the crankshaft with a break to absorb the power, you could measure the force on the break with a lever attached to a scale. This was called Break Horse Power, and it was how early outboard were rated. Just when we thought we had everything settled, it was discovered horse power sold motors. Suddenly it was up to the engineers to squeeze every last drop of power out of there test engines. It became common in the early ’30s the round up to the next HP if you managed to get past a HP mark. Unfortunately production motors could not be assembled with the same care and frequently fell short.
Most outboarders didn’t notice, because they always thought they were going faster than they actually were. However Some speed enthusiasts noticed and complained. Soon the complaints mounted, and caused the major motor manufacturers to come together to solve the problem. They formed the National Outboard Association in 1933. The agreement was that representatives of the competing companies would come in and chooze three motors at random to be tested for horse power. The averaged power of the three would be the cerctified power of that model. Over night, some models lost three horse power. Evinrude and Elto hung brass medallions on there models proudly proclaiming "NOA certified horsepower". From what I have seen on Ebay, some must think those medallions are gold. That’s the way it was until World War Two, which put civilian outboards on hold for the duration . After the War the pent-up demand for outboards was fantastic. The sequestered 1942 models were relabeled and quickly sold.
Meanwhile there was frantic retooling to build the motors that were on the drawing board for peaceful times. Using wartime research & development, money and experience from war contracts, Everyone was ready to build the outboard of the future. There was little time to certify horse power as the Magazine advertisements were done almost before the motors were assembled. The Martin 60 was estimated to put out six horse power. It tested at seven and a half. Evinrude had not put there prewar gearshift patent into service. Johnson used it for there QD model, Evinrude used it on there Fastwin. Mercury used there Target Drone motor experience to build some truly high performance outboards. Carl K thumbed his nose at NOA and under rated his new outboards. After that it was whatever marketing thought the market would bare. Finally the government stepped in and required that rated horse power be taken at the propeller shaft. – was that 1984? . ❓ . . . . 😀
