Do You Really Need a Stainless Steel Prop?

Gosh those stainless steel props are purdy. They just look faster than standard ol’ black paint aluminum props. But are they faster? Is speed the main reason to dump the aluminum prop and upgrade to stainless steel?

I can unequivocally deny the myth…stainless props are not necessarily faster and speed isn’t the most significant reason to run one. The best feature of a stainless steel prop is the way it enhances the handling characteristics of your boat.

Note that there are many different special applications for trick SS prop designs. What I’m referring to here is the standard stainless prop designs…3, 4 maybe even 5 blade models that are generally applicable to most boats. So we aren’t talking surface-piercing or racing props, just the prop you’d use on a family runabout or Montana fishing boat.

When you take off an aluminum prop and replace it with stainless, the most noticeable difference is the immediate change to a Cadillac ride. While aluminum props are “slippy” and prone to cavitation/ventilation, especially when trimmed up a bit. Stainless props hold the water very well…less slip means more efficiency which might add a mile an hour to your top speed. What you notice isn’t the speed, it’s the solid and positive handling. When you minimize slip and cavitation, the result is positive steering response and a more controlled “feel” while planing.

It’s almost like the difference between driving a car on wet pavement vs dry…you can still drive safely on wet pavement but your vehicle seems “washy” in corners and on bumpy stretches. It verges on feeling squirrely driving on wet pavement. On dry pavement your car just seems more “stuck” to the road, steering is more direct…your vehicle actually feels settled as opposed to squirrely. That’s similar to the difference you feel with a stainless steel propeller.

Much of this stronger hookup is due to the cupping on the blades of a stainless prop. That cupping on the trailing edge of the blades helps the prop hold the water and avoid cavitation/ventilation. And since the cupped stainless prop holds the water so much better it allows you to trim your engine or outdrive much higher. Of course, the higher you trim up while planing the more of the boat’s hull comes up out of the water. Less “wetted surface” means less drag and consequently a couple mph of added speed. But nice as the extra speed is, the extra range of trim is even more significant.

With aluminum props, the limited range of trim before cavitating and the noticeable amount of slippage when trimmed up and cornering typically trains boat owners to use trim moderately and some folks don’t use their trim much at all. With an SS prop, your boat handles so much better and your trim range is so much more broad that you learn to tailor your ride by adjusting trim all the time: trim up for better planing performance; trim down when contacting wakes or  chop; trim up to reduce spray; trim down to pull kids on tubes…You’ll find yourself driving with the trim button to dial in the smoothest ride or the fastest ride or the most settled (not squirrely) ride…how your boat rides is almost entirely controlled by the combination of throttle and trim and you quickly adapt to having the stainless prop and start choosing how your boat rides by adjusting the trim.

We could talk about the fact that better water holding ability means a stainless prop will let you mount your engine higher (or run a jack plate) thus reducing drag and increasing top speed. We could talk about the fact that less slippage means better fuel economy…and that trimming to get less “wetted surface” also means better fuel economy and the higher engine mounting to reduce drag also increases fuel economy…But these are all small factors compared to the gains in handling and control.

On my own tiller boat—no consoles and driver sitting in the back of the boat driving by hand—I run a stainless prop that is designed for stern lift. So instead of running low in the water in that heavily laden back end of the boat (yes, I just called myself fat in a nice way), I get the benefit of a drier ride with my boat running what feels like several inches higher in the stern than when I run it with an aluminum prop.

So it should be fairly clear that I’m a big fan of stainless steel props. Over the decades I’ve run Yamaha Pro Series, Turbo and Turbo II, a variety of Merc SS props and currently I’m running two different Power Tech stainless props—one for high altitude here in Montana and another version with a bit more pitch for sea level. There are probably a half dozen stainless props laying around my garage from past boats or past propping experiments…Yes, SS props are expensive to buy and expensive to repair when you try rototilling the bottom of the lake. But there is no other single item that will change your boat’s ride and controllability like a stainless steel prop.

So if you are tired of having a squirrely boat…if you don’t feel like you have total control of your ride…or if you can’t get the boat to plane high enough to keep spray to a minimum…and of course, if you just want an extra mile an hour or two on the top end…taking one minute to install a stainless steel prop will prove to be the best boating decision you can make!

P.S. Your current aluminum prop will make a fine spare prop for “just in case.”