Yes they are, I have 2 "Aquasonics" and they are '55's. As a young fishing guide in Ontario, I ran a 15h.p. for years and they are a pretty decent trolling motor too, when everything is right. In time, it began to pop out of forward when under load so I repaired it to perfect again and sold it for good money. We used it on portages to other lakes and it wasn't too heavy to handle. You can even get coils and tune up kits at your local Napa, O'Rielly.....whoever can get Sierra parts. Coils are only $15 each. Be sure to use solid core plug wire....not silicone/carbon core.