Based on what I had read about props I decided, many years ago, to try a 4 blade prop on my Nitro NX 882 w/ Merc 150 hp XR6. I bought a 4 blade aluminum prop 14" 23 pitch because it was considerably less expensive than Stainless Steel. The aluminum prop did everything I was looking for. Better hole shot, more "bite" so better control in rough water conditions. Another potential benefit, I thought, was that the softer aluminum prop would bend if a hard object was struck and protect other lower unit components from damage potentially. Kind of a "shear pin" effect. Speed is not an issue as I rarely approach 4000 rpm. I can't even spell "WOT".

I just repowered with a new 150hp Merc Pro XS and I am told that I can't run an aluminum prop, 3 or 4 blade, on my new motor. The reason is said to be that the Pro XS develops a lot more torque than my old XR6 and the aluminum prop would distort under load and cause the motor to "over rev".

I can't get this to make sense other than the guy wants to sell me a $1000 s.s. prop.

I've been running a 4 blade aluminum on my old XR6 for over 10 years with absolutely no issues and all the benefits I described earlier. The aluminum props I have purchased all state that they are suitable for use on outboards up to 300hp. I never felt the need to spend the additional $800 or so because the performance of the aluminum prop was excellent. I am a believer in the 4 blade , for my purposes, and I will spend the money for s.s. if necessary.

Am I getting B.S. or is there validity in what I'm being told?

Thanks in advance.

I looked on Mercs website and it looks like you can do it. If you shop around you can probably find a SS alot cheaper then 1k

Mercury Marine | USA

Spitfire | Mercury Marine

I tinkered with props of various pitches, material, and number of blades a few years ago. I was hell bent on getting a higher top speed out of my boat. It was a fruitless waste of time and money.

Turns out the one that worked the best was the one I was already using.

1 hour ago, Nitro 882 said:

Based on what I had read about props I decided, many years ago, to try a 4 blade prop on my Nitro NX 882 w/ Merc 150 hp XR6. I bought a 4 blade aluminum prop 14" 23 pitch because it was considerably less expensive than Stainless Steel. The aluminum prop did everything I was looking for. Better hole shot, more "bite" so better control in rough water conditions. Another potential benefit, I thought, was that the softer aluminum prop would bend if a hard object was struck and protect other lower unit components from damage potentially. Kind of a "shear pin" effect. Speed is not an issue as I rarely approach 4000 rpm. I can't even spell "WOT".

I just repowered with a new 150hp Merc Pro XS and I am told that I can't run an aluminum prop, 3 or 4 blade, on my new motor. The reason is said to be that the Pro XS develops a lot more torque than my old XR6 and the aluminum prop would distort under load and cause the motor to "over rev".

I can't get this to make sense other than the guy wants to sell me a $1000 s.s. prop.

I've been running a 4 blade aluminum on my old XR6 for over 10 years with absolutely no issues and all the benefits I described earlier. The aluminum props I have purchased all state that they are suitable for use on outboards up to 300hp. I never felt the need to spend the additional $800 or so because the performance of the aluminum prop was excellent. I am a believer in the 4 blade , for my purposes, and I will spend the money for s.s. if necessary.

Am I getting B.S. or is there validity in what I'm being told?

Thanks in advance.

Congrats on the new motor.

I repowered my rig a few years back as well. I am running a ss Tempest prop and it's been fantastic.

I can not relate to your perspective on the prop choice.

You just outfitted your boat with the latest and greatest motor Mercury offers. The prop is where these units are able to provide you with what you paid for. Using an inferior material will give you inferior performance. Sort of like putting re-tread tires on a new corvette. Your new motor is reliable, efficient and powerful. Your prop choice effects at least two of the three.

I would not recommend deliberately undermining a motors ability.

Perhaps simply consider the ss prop upgrade as part of the repower.

Good Luck

A-Jay

I had to go back and read my post again because, so far, the responses don't come close to answering my simple query.

For my own reasons, after over 60 years of owning/operating outboards, I prefer a 4 blade aluminum prop. I was simply looking for some legit reason why I'm being told I can't run one on my new Pro XS. The prop I intended to put on the new motor is not a "retread". It's a new Mercury Spitfire that is, according to Merc, suitable for high-performance motors up to 300 hp.

I'm not trying to determine the best prop for me. I am settled on a 4 blade aluminum 14"/21 pitch, specifically, based on over 10 years running one on my Merc XR6.

I don't consider a S.S. prop to be an upgrade. They provide more top end speed and are "prettier" but those attributes are of no importance to me. As I've said before (tongue in cheek) I can't even spell WOT.

Also, I'm capable of "shopping around" and if/when it becomes imperative that I equip my motor with a Stainless prop, I will do so. I would just like to understand why.

Thanks for the effort but I still have questions and, it seems, I'll have to look elsewhere for an answer.

Best wishes

PS I have 3 S.S Tempest 23 pitch props in my shop. One from my original XR6, a spare I bought cheap at a garage sale (for a backup), and one given to me by a friend who sold his boat and had an extra laying around.

'

You can run an aluminum 4 blade on your 150XS but I'd go with the Black Max made by Mercury but thinking that's a 3 blade.

I've also only run 4 blade aluminum on all my boats over the years.

Well said @A-Jay. Having a SS (a 23p Fury in my case) just seems like a no-brainer attached to the business end of a ProXS. As to why SS as opposed to aluminum- it is my understanding the SS prop doesn’t flex under load as aluminum does giving much better performance.

22 minutes ago, Nitro 882 said:

I had to go back and read my post again because, so far, the responses don't come close to answering my simple query.

For my own reasons, after over 60 years of owning/operating outboards, I prefer a 4 blade aluminum prop. I was simply looking for some legit reason why I'm being told I can't run one on my new Pro XS. The prop I intended to put on the new motor is not a "retread". It's a new Mercury Spitfire that is, according to Merc, suitable for high-performance motors up to 300 hp.

I'm not trying to determine the best prop for me. I am settled on a 4 blade aluminum 14"/21 pitch, specifically, based on over 10 years running one on my Merc XR6.

I don't consider a S.S. prop to be an upgrade. They provide more top end speed and are "prettier" but those attributes are of no importance to me. As I've said before (tongue in cheek) I can't even spell WOT.

Also, I'm capable of "shopping around" and if/when it becomes imperative that I equip my motor with a Stainless prop, I will do so. I would just like to understand why.

Thanks for the effort but I still have questions and, it seems, I'll have to look elsewhere for an answer.

Best wishes

PS I have 3 S.S Tempest 23 pitch props in my shop. One from my original XR6, a spare I bought cheap at a garage sale (for a backup), and one given to me by a friend who sold his boat and had an extra laying around.

'

Thank you for the supplemental information.

Since you value drivetrain protection, run a conservative throttle, and prefer a budget-friendly setup that still delivers excellent bite and holeshot (especially in a 4-blade configuration), sticking with a high-quality aluminum prop makes perfect sense—regardless of what the performance charts say.

Good Luck

A-Jay

I'd bet your new engine has enough torque to "throw a blade". I've only heard about it from the Team Marine guys on YouTube, but it sounds like it would cost way more than a stainless steel prop.

My boat came with a 4 blade but a lot of the true bass boats come with a 3 blade on the same engine. I have an aluminum Deep-V.

There might be potential warranty issues - I’d say call Mercury direct to verify that there’s no problem there.

Your 882 is a relatively heavy hull - with the increased torque of the ProXS, there might be some valid concern about excessive blade flex under load, leading to catastrophic failure. I’d definitely consult Mercury directly before committing to anything.

When I asked Mercury Marine about the difference in torque value between my old XR6 and the new Pro XS they don't have a specific value in foot/lbs like we get when we "dyno" a car engine. They talk about where in the acceleration curve the torque is delivered. The following is directly from Mercury.

"Bottom Line: If you want maximum initial acceleration and quick hole shots the XR6's high low-end torque is an advantage. If you prefer smooth, consistent power and better control at (wait for it) wide open throttle, the Pro XS's torque delivery and EFI tuning make it a strong choice."

All this talk about flexing and catastrophic blade slinging refers to the WOT gang who screw around with props trying to eke out another 1/2 mph on the GPS at 5500/6000 rpm.

My 'bottom line'---from what I've gleaned through my researching this aluminum vs S.S. issue, if aluminum was going to pose a problem, it would have done so on the XR6 that I ran for the last 10 years with an aluminum prop.

Just for clarity sake, I didn't say that drivetrain protection was a factor in my preference for the aluminum prop. I try to steer around hard stuff. With all the talk about flexing, and where flexing is not an issue at the rpm's that I typically run, it occurs to me that, in the event of a run-in with 'hard stuff' aluminum would take some of the stress off of the more rigid drive line components. Just t to make lemonade out of lemons.

Here's the kicker. This all started when I put my new motor equipped with a new Mercury 4 blade prop in for the first time. I ran at headway speed for a while to be sure the engine was properly warmed up and the put her up on plane. I never exceeded 3000rpm and within just a few minutes an alarm went off. Shut down, spent the appropriate time cursing, and started up again. Same result. An alarm shortly after running at around 3000rpm. Called the dealer (a bunch of things under my breath) and arranged to come in to hook up to his computer for a diagnosis. His claim is that the aluminum prop was flexing causing the engine to "over-rev" creating the alarm. I'm picking the boat/motor up this morning. I'm going to install one of my S.S. props and I'm going to the lake. I hope to hell I'm wrong, but my bet is that the alarm is going to sound again and I'll be back to the dealer before noon, really ticked, to deal with whatever the real issue is. It just dawned on me, a couple times when I was playing with the trim, I got too high and the prop broke loose. I'll bet that is what the ECU recorded as an over-rev event.

Anyway, I spent $15K to have a dependable motor and not waste more of the summer dragging my boat to and from the shop.

Help me, Lord.

4 strokes have a slightly lower gear ratio and at 3,000 rpm you’re just about hitting the torque peak. It is entirely possible that it’s slipping just enough to make the computer think that you spun a hub and kick an over speed alarm.

Give the stainless a shot and see what happens. I remember “prop wars” with my boat - went through a bunch of different ones before figuring out it’s happy place.

Okay, picked up my boat, went to the lake and changed to a S.S. 23 pitch prop. Launched the boat, let the motor warm up and tried to get it on plane. Continuous beep started almost immediately. Motor acted like it was in guardian mode right away. Shut it down, restarted, throttled up to get on plane and, again, immediate alarm but this time intermittent (6 beeps).

As I said earlier, this blaming the 4 blade aluminum prop I've been running flawlessly for years was ***.

I left the boat with the dealer and told them I didn't want it back until they took it to the lake and ran it without alarms going off.

I'm getting a real bad feeling about this motor that is going to take a lot to shake. The dealer is doing the same thing many on here are doing---guessing. I spent 15k to have a reliable motor that I could have confidence in and wouldn't strand my 80-year-old ass out in the middle of the Kissimmee Chain this winter. It is going to take many trouble-free outings to convince myself that this motor is reliable. If I could have a do-over, I wouldn't have made the purchase. If I threw a bit of money at my old XR6, I'm sure I could have gotten her to take me to the end my line. Just wanted the surety that apparently money can't buy.

2 hours ago, Nitro 882 said:

Okay, picked up my boat, went to the lake and changed to a S.S. 23 pitch prop. Launched the boat, let the motor warm up and tried to get it on plane. Continuous beep started almost immediately. Motor acted like it was in guardian mode right away. Shut it down, restarted, throttled up to get on plane and, again, immediate alarm but this time intermittent (6 beeps).

As I said earlier, this blaming the 4 blade aluminum prop I've been running flawlessly for years was ***.

I left the boat with the dealer and told them I didn't want it back until they took it to the lake and ran it without alarms going off.

I'm getting a real bad feeling about this motor that is going to take a lot to shake. The dealer is doing the same thing many on here are doing---guessing. I spent 15k to have a reliable motor that I could have confidence in and wouldn't strand my 80-year-old ass out in the middle of the Kissimmee Chain this winter. It is going to take many trouble-free outings to convince myself that this motor is reliable. If I could have a do-over, I wouldn't have made the purchase. If I threw a bit of money at my old XR6, I'm sure I could have gotten her to take me to the end my line. Just wanted the surety that apparently money can't buy.

Sorry your repower is turning into a bogus experience.

Hope they get it sorted out in short order and you can have the 'good feeling' back again.

A-Jay

One thing to check. You didn’t mention if you did it, but the breakin procedure for the proXS for the first two hours is to run it at varied throttle up to 4500 rpm and to NOT run it at a constant throttle in that time. I don’t know if running a straight 3k rpm like I’m reading into your post would kick an alarm, but it is worth checking.

1 hour ago, casts_by_fly said:

One thing to check. You didn’t mention if you did it, but the breakin procedure for the proXS for the first two hours is to run it at varied throttle up to 4500 rpm and to NOT run it at a constant throttle in that time. I don’t know if running a straight 3k rpm like I’m reading into your post would kick an alarm, but it is worth checking.

I said I never exceeded 3000 rpm. If you really read the post you didn't understand it.

I can certainly understand your frustration, I'd be ticked 😡.

Point blank, it's a issue with the motor itself and Mercury has a long standing record of making it right.

I don't buy into all this prop flexing hupla because it's aluminum.

Why offer an aluminum prop if it's problematic 🤔.

I will say that when getting on plane, I'm full throttle trimmed down and gradually trim up.

9 hours ago, Nitro 882 said:

Okay, picked up my boat, went to the lake and changed to a S.S. 23 pitch prop. Launched the boat, let the motor warm up and tried to get it on plane. Continuous beep started almost immediately. Motor acted like it was in guardian mode right away. Shut it down, restarted, throttled up to get on plane and, again, immediate alarm but this time intermittent (6 beeps).

As I said earlier, this blaming the 4 blade aluminum prop I've been running flawlessly for years was ***.

I left the boat with the dealer and told them I didn't want it back until they took it to the lake and ran it without alarms going off.

I'm getting a real bad feeling about this motor that is going to take a lot to shake. The dealer is doing the same thing many on here are doing---guessing. I spent 15k to have a reliable motor that I could have confidence in and wouldn't strand my 80-year-old ass out in the middle of the Kissimmee Chain this winter. It is going to take many trouble-free outings to convince myself that this motor is reliable. If I could have a do-over, I wouldn't have made the purchase. If I threw a bit of money at my old XR6, I'm sure I could have gotten her to take me to the end my line. Just wanted the surety that apparently money can't buy.

Okay, 6 beeps says it all…. That’s a sensor or low voltage fault. Something as simple as a bad connection (or a sketchy battery) will cause the exact symptoms you describe.

As much as I love my hot rodded Black Max, I likely will repower to a new 4 stroke in the future. When that happens, I expect I will see the same hiccups as you’re experiencing.

Edited 6 hours ago6 hr by ElGuapo928
Poor grammar