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A Solid 10


A bright red outboard engine mounted on the stern of a fiberglass dinghy has these two youngsters enthralled; for them, it’s the stuff that dreams are made of. More precisely, it’s the new-for-1958 Mercury Mark 10 Alternate, a twin-cylinder, 10-hp power plant that comes with a 12-volt electric starter, a generator and a host of other gear.

Manufactured by the Kiekhaefer Corp. in Fond du Lac, Wisconsin, the Mark 10 Alternate’s features, listed in the pages of a September 1957 boating magazine, include an automatic transmission with a single-handle shifter on the tiller that also controlled the throttle. Below the waterline, the lower unit’s Glide-Angle design was meant to slough off underwater obstacles: “stumps, rocks and thick weeds,” as the sales pitch went. The Flo-Torq propeller drive had rubber bushings, which eliminated the use of the shear pin.

The Mark 10 Alternate was the product of years of development. When World War II ended, Karl Kiekhaefer understood that Americans were going to want to go boating, and outboards were a good way to get them out on the water. In 1947, Mercury introduced the 10-hp, two-cylinder Lightning, also called the Super Ten. The 1952 Cruiser outboard was a further development, updated with a twist-grip throttle and a
“forward, neutral, reverse” gear set that would eventually be used on the Mark 10 Alternate.

Outboard engines such as this one helped to attract a new, young generation of Americans to the pleasures of boating in the 1950s and 1960s. That’s one reason the Mercury Mark 10 Alternate is still valued today among antique outboard collectors. Models in various states of repair are readily available on the internet. One enthusiast calls the bright red outboard “a 10-horse gem.” 

This article originally appeared in the February 2020 issue.