Is an Aluminum or Stainless Prop Better

[@chiphill4856]

Aluminum: cheaper, but lightweight and easily damaged, must be replaced often in locations where the bottom is near, slower because blades flex under load and lose pitch Stainless: expensive, but faster because blades are stiffer, less likely to be damaged by contact with the bottom, added weight improves prop momentum, more durable, maintains shape and pitch over time, internal rubber hub is designed to prevent gear case damage Here on the SC coast we have oyster bars and sandbars everywhere, stainless is by far the most popular and economical.

[@tinman-uf4to]

I love these videos, this guy is great! I’m a new boat owner and really enjoy the videos!

[@garyira6857]

I dont mean to be so off topic but does someone know a trick to log back into an Instagram account?? I somehow lost my password. I would love any help you can give me.

[@hd95]

Good video. Why didn't you mention using a rubber hub to prevent drive train damage with stainless?

[@mwilliamshs]

4:16 "...transfer of energy goes through the prop blade, into the hub..."

[@doctorhydro]

Norm Macdonald's brother did an excellent job explaining this.

[@BellavistaPEI]

Very good video! My friend has stainless on his twin 5.0's and hit a rock last year....insurance paid out $8000.00 for repairs....TO ONE OUTDRIVE!!!! I'm thinking the shiny looks pretty....PRETTY EXPENSIVE!!!

[@Boaters_hub]

What about the stainless probs with a sacrificial inner hub designed to be replaced if you strike bottom. Its the best or both worlds in my opinion

[@bigtrout]

I fish in one lake that’s fairly shallow and full of stumps & standing Cypress. I hit a stump at less than 10mph. It sheared off one full blade and half of another on my aluminum prop. 4 miles from the landing it took almost two hours to idle/limp back to the dock with one bent blade. I’m glad I had aluminum and shudder what may have happened to my lower had it been stainless. Replaced @ under $150. For a few more miles per hour I don’t see the value in stainless, 40 mph is plenty fast for me.

[@chiphill4856]

Stainless would have survived much better without lower unit damage. All motors are built to withstand contact with logs and sandbars, etc. There are videos on YT showing these tests during product development where the motor must survive hitting a stationary log running wide open. Aluminum is a bigger hassle because they must be replaced frequently. The poor balance and vibration of a damaged aluminum prop causes bearing and seal failure over time.

[@hulkhuggett]

I agree about the speed. 40 mph is plenty fast enough for me too. 40 in my boat feels like 100. 😮💩

[@marcvaillancourt9141]

I have watched many of your videos. If I lived within travel distance to Len's Cove, I would have purchased my sweetwater from you Sean.

[@dirkboom960]

Len, You forget to mention that aluminium propellers put les strain on the forward and reverse gears when you engage them. The 'clonk' that you feel and hear is much less with alu because it's a lot lighter.

[@boatinglessons]

Great point Dirk!

[@chiphill4856]

I believe that has more to do with the engine design. Mercury's shift waaaaay smoother than Yammies. We run all stainless inshore and offshore were I live in SC.

[@dirkboom960]

@@chiphill4856 If an engine engages it’s gear with less ‘clonk’ than Another, it doesn’t necessarily mean that it’s a beter engine. It coul just be the angle of the gears are different ( more steep). These are mostly a little less durable.

[@chiphill4856]

@@dirkboom960 A more efficient machine is a quieter machine. Noise is lost energy and it means something is impacting and vibrating and possibly wearing. Plus the smoother shifting Merc's are simply more pleasant and easier to operate. The Skyhook joystick is a dream.

[@jimwhall6609]

I’m always amused by the strident opinions on this topic. I run a 4.3 mercruiser alpha one, and my son and his buddies are learning how to drive it so one day they can take over. We tow lot. I run a 17” aluminum 4 blade with a 3 blade backup.

[@Nick_G7IZR]

Stainless blades are thinner so you will usually see an improvement in acceleration or you can change the pitch by an inch and improve top speed.

[@AlexGarcia-ew2fv]

Also heavy ss props.hav a tendency 2 wear out the Outer Prop.shaft bearing n seal>>> Due to the added weight

[@VISTATREKKER]

Excellent as always

[@violetsydney4942]

Aluminum Propellers Lightweight: Aluminum is a lighter material than stainless steel, making aluminum propellers easier to handle and install. Less expensive: Aluminum propellers are generally less expensive than stainless steel propellers. More flexible: Aluminum propellers are more flexible than stainless steel propellers, which can help to reduce vibration and noise. Less durable: Aluminum propellers are less durable than stainless steel propellers and are more susceptible to damage from rocks and other objects. Stainless Steel Propellers Heavier: Stainless steel is a heavier material than aluminum, making stainless steel propellers more difficult to handle and install. More expensive: Stainless steel propellers are generally more expensive than aluminum propellers. Less flexible: Stainless steel propellers are less flexible than aluminum propellers, which can lead to increased vibration and noise. More durable: Stainless steel propellers are more durable than aluminum propellers and are less susceptible to damage from rocks and other objects.

[@naturalstatepoolandspallc338]

i use aluminum on my pontoon just so hits will damage it instead of the lower unit

[@panosxristodoulos]

Hello, I'm running a suzuki df90a on a 5.20 m rib . The engine's max rpm is 5800 and I'm seeing this with a 14X19 aluminium propeller hitting 35 knots at wot. If I change to a 14X17 SS prop I suppose I'll hit the same max rpm. Will I see any difference in acceleration or top speed , considering my small engine ? Thank you in advance!

[@NeilGraham.I.M.F]

Will a stainless steel prop even make a difference on top end speed with a 40 horsepower motor

[@paulkersey2179]

Thanks for the help.

[@boatinglessons]

Our pleasure Paul!

[@jaroslav841]

Thank you for an interesting review. I am missing though something I have never seen answered in any forum or video on stainless vs aluminum prop comparison. That is, what would be an impact on the Outboard RPM, if all other things being equal (pitch, cup, rake, diameter, ect), and you only change the material of the prop from Aluminum to Stainless steel (or other way around)? Would Outboard RPMs increase or decrease? For how much approximately? Or would there be no RPM change and only top speed would change - increase? If so, why no change in RPM?

[@boatinglessons]

All other things being equal, your RPM would decrease slightly (the exact amount would depend on the application). I would bank on losing about 150 - 200 RPM at WOT (wide open throttle).

[@timwilson9922]

@@boatinglessons that being said, would it be best to slightly change pitch when going from aluminum to stainless,like say from an 11 pitch to a 13 pitch to maintain the proper RPM range? I have a 14X11 prop on my new pontoon with a new 75 HP Mercury and I’m wanting to go to a stainless prop, would I want to go to a 13 pitch?

[@SeanHorsfall]

@@timwilson9922 to maintain RPM you would need to decrease the pitch. If you were at an 11” aluminum, you would need to go to a 10” stainless to maintain RPM (approximately). That may not be available however.

[@Scablands_Scavenger]

I am starting to get more confused the deeper I dive into this. I feel like my boat is under propped. I have a 16 foot Aluminum with a 90 horse Evinrude E-tec. I cavitate badly if I don't slowly roll onto the throttle on acceleration and I reach max RPM at like 3/4 throttle (5500rpm I believe). The boat weighs 1100 lbs, motor is 290ish with a 6horse kicker and maybe a hundred pounds of gear etc. Top speed is 28-32 mph. I feel like the motor has much more to give or could run at lower RPM for same speed but worried a stainless prop would be an issue as I fish in rocky areas.

[@boatinglessons]

I would try a larger pitch aluminum prop first to see if it helped (before switching to stainless). Also it could possibly be mounted just a bit to high on your transom and worth checking.

[@Scablands_Scavenger]

@@boatinglessons Thank you for the suggestions, I will definitely look into both!

[@guygaspar5828]

Have your prop vented; that will reduce cavitation.

[@joeyslife8845]

Gas any different ?

[@grancito2]

No mention that shallow water use, especially shell bottom, will destroy an aluminium prop in short time.

[@ThatGuy-sd3zl]

True, I’ve hit sand often with my stainless and it only suffered a few scuffs on the edges. I’d probably would have replaced 5 or more aluminum props by now.

[@NeverEnoughPyro40]

You’re not supposed to hit the bottom with your prop! When you hit bottom it stirs up sand and mud and that ends up getting sucked into your cooling system, Not good for your engine or impeller! Why don’t you invest in a good depth gauge!

[@grancito2]

@@NeverEnoughPyro40 Depth gauges dont work in water that is half a meter deep, and that is a common depth here, I have not had engine problems because of sand, nor anyone I know.

[@chiphill4856]

@@NeverEnoughPyro40it's very simple: if you haven't been aground, you haven't been around! No one is immune!

[@waagle888]

Aluminum props save lower units

[@boatinglessons]

100%!

[@chiphill4856]

Only in catastrophic cases. Aluminum props run crappy because they get nicked up and bent easily. Any contact with the bottom, even sand, will alter the shape. The vibration from running a misshaped and damaged aluminum prop is causes bearing and seal damage. I run stainless on the coast of SC for 45 years and contact the bottom routinely, with zero lower unit damage or prop damage in that time. Aluminum props don't stand a chance. Additionally, stainless is faster for a given pitch with better acceleration and economy.

[@raulfernandez9111]

My boat is paid off and I don't buy insurance. I'll stick with aluminum to save the outdrive.

[@hawgstalkaztv5985]

I bet the aluminum prop is the reason I can lift the bow at wot

[@abtechgroup]

sucking air from the surface is ventilation. Cavitation is the gas formation from the pressure drop on the leading edges of the blades when the water curls around the edge

[@shot9702]

It seems like this assumes all fresh water. Is one better in a salt water environment?

[@boatinglessons]

In salt water, a stainless propeller will increase the rate of corrosion to your lower unit.

[@chiphill4856]

@@boatinglessonsthats what zincs are for

[@michaelpiller1513]

I just bought a Monterey 224 fs (300hp Volvo + SX drive) and it came with an aluminum 21 pitch prop. Will I achieve greater top end speeds if I move up to a 23 pitch stainless? What pitch would bring the highest top end? Thanks.

[@boatinglessons]

Michael, do you know what wide open throttle RPM (trim up slightly, light load) your engine is currently getting with the aluminum prop?

[@michaelpiller1513]

@@boatinglessons I am not exactly sure since I haven't driven the boat yet. It's probably around 5000.

[@boatinglessons]

@@michaelpiller1513 You need to do that first before you think about changing props. A 23 Stainless may be too much for it. I suggest a good run in the new season and very carefully check that vs. the manufacturers spec and then you can make a better choice for a swap.

[@michaelpiller1513]

@@boatinglessons Ok, will do. How fast do you think the boat will go with the current prop? I'm thinking low to mid 50's.

[@boatinglessons]

@@michaelpiller1513 yes, low 50s is a reasonable expectation :-)

[@j.b.7525]

There are motors that just work better with stainless props. Newer Mercurys V8 class 225 - 450hp really wake up with the correct stainless prop. All of our aluminum test props don't even come close.

[@boatinglessons]

That is a good point! There are some engines that they only offer stainless (or aluminum) for also. I should have clarified that there is a choice for engines between 70 and 250hp typically

[@Nick_G7IZR]

Aluminum? It's aluminium :)

[@scottking9038]

This year I bought a brand new 2021 Lowe FS1700 Deep V 17" feet boat 95" beam, came with four blade 13" 17 Pitch on Merc 4 stroke 115 (none XS or Command Thrust) engine. 6000 RPM WOT max speed 43 MPH. Used Merc prop selector and tried a 4 blade 12.5" 19 pitch and @ 5,500 RPM WOT speed is 46 MPH. However when cornering or turning I am getting cavitation issues. I was trying different size props even 3 blade prop due to cavitation issues. Also due to the trailer lock mode I can't raise the trim up when going very fast. I heard others with similar issues got to the Merc X7 stainless but as you say, this cost 3x more. But is it worth the extra money to stop the cavitation issue? As others say, stainless steel is nice and pretty but if I hit a log or bottom it could be very costly repair. Is there a different size I should try??

[@boatinglessons]

The right prop for performance may be a 17 pitch Spitfire four blade stainless. You will have more impact risk, but the results may be worth the risk

[@chiphill4856]

Stainless is almost always a better performer. Aluminum is shortsighted because they are damaged easily and disposable. Props have a rubber hub inserted between the blades and the shaft to prevent gearcase damage. If you hit something hard like a rock running 50mph, no prop or lower unit will survive. Even a whiff of the bottom will distort an aluminum prop, and there goes your top speed, economy and acceleration. Vibrations from a damaged aluminum prop causes bearings and seals to fail over time.

[@benedictcumberbatch4275]

Put both these on a boat and get your gps out.

[@azcharlie2009]

This guy knows about props? He's turning it the wrong way.

[@boatinglessons]

Lol, they do turn that way in reverse ;) Thanks for catching my error :)

[@azcharlie2009]

@@boatinglessons No big deal. I do have a question, though. We have a 2007 Sea Ray 340 sundancer with twin bravo 3 drives. We've owned it since 2010. The props have what looks like grey paint on them, along with some calcium build up on the starboard props. What is that? The boat has only been lightly used in those 13 years we've owned it. Maybe 100 hours?

[@boatinglessons]

@@azcharlie2009 I have no idea. I think I would need to see a picture which you can send to [e-mail] if you want :-)

[@jasonhurdlow6607]

Not going to lie... I was slightly triggered when he did that. :)