Prop Change: From Aluminum to Stainless Steel

[Lakeside]

I'm looking for some advice regarding the change from aluminum props to stainless steel. I have a 1988 Sea Ray Sundancer 270 with twin 4.3L V6 engines. It's been suggested that I consider changing the props to improve the boats performance. Currently, she cruises nicely at 3400 rpm and about 24 mph in good conditions. If I change to stainless, what would be the expected improvement. Also, what would be the recommended specs for the stainless props? Thanks!

 

[rob83srv225]

I changed my prop from alum. to stainless, kept the same pitch and noticed a big diffrence. hole shot was much faster,more top end speed, stays on plain at lower speeds.... Robert.

 

[fwebster]

In theory, the blades on a stainless prop are stiffer and don't flex as much as those on an aluminum one. Aluminum props will flex a little as the resistance of the water tends to striaghten out the blades. As the blades flex you slightly reduce your effective pitch. Since the stainless prop doesn't flex as much, you don't lose as much effective pitch and you usually more torque delivered at low speeds (better hole shot) and more top end speed (marginally).

With boats there is usually a trade off when changes are made. In this case the stiffer stainless blades give you a little better performance, but they are also a lot tougher. That means they are harder to damage, but at the same time, when you hit a submerged object, a stainless prop is much more likely to cause a bent shaft or damaged gear case than aluminum is since aluminum is softer and sacrifices itself to damage before damaging more expensive drive components.

The other trade off is that, while stainless can be repaired, it is usually a more expensive to do or to replace a blade on a stainless prop than on an aluminum one.

 

[Redhook98]

In theory, the blades on a stainless prop are stiffer and don't flex as much as those on an aluminum one. Aluminum props will flex a little as the resistance of the water tends to striaghten out the blades. As the blades flex you slightly reduce your effective pitch. Since the stainless prop doesn't flex as much, you don't lose as much effective pitch and you usually more torque delivered at low speeds (better hole shot) and more top end speed (marginally).

With boats there is usually a trade off when changes are made. In this case the stiffer stainless blades give you a little better performance, but they are also a lot tougher. That means they are harder to damage, but at the same time, when you hit a submerged object, a stainless prop is much more likely to cause a bent shaft or damaged gear case than aluminum is since aluminum is softer and sacrifices itself to damage before damaging more expensive drive components.

The other trade off is that, while stainless can be repaired, it is usually a more expensive to do or to replace a blade on a stainless prop than on an aluminum one.

In other words, don't hit nuthin'.

My SeaRay guy told me to step down from SS to aluminum on my AJ. He said it would eliminate any corrosion issues and is actually better performance-wise for the boat. I bought a couple aluminum props new and think they are great. Couldn't believe how heavy the SS ones were on a B2!!!! :wow:

 

[CAGE RATTLER]

Im trying to dial in my prop performance and was wondering what going from a 3 blade aluminum to a 4 blade would be performance wise. I read somewhere that a 4 blade would improve all aspects so it sounds like a no brainer.

Any opinions??