prop question

Rugglesworth

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Jul 6, 2023
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I just picked up a beautiful 1995 searay 180 signature 4.3lx with alpha I. I took it out into the ocean and the hub spun.. It's the original prop, fair enough. It has a 3 blade 21P prop on it. I can just redo the hub to get back on the water but as I am going to be towing my teenagers on a wakeboard all summer I wanted some feedback on if I should be looking at a 4 blade turning point prop or a stainless prop with a 19p... as the prop spun I never got to see how it performed with the original prop.

thanks
 

Chris51280

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It is difficult to compare with most other boats. but the 4blade 19p is a good start and will most likely fit you perfectly. I run it on mine. The top end suffers a bit in speed but i don't run it like that. the prop with hub runs about 150 on amazon
 

jimmbo

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Turning Point, IMHO, has had very poor QC in the past. I remember opening several Boxes, and finding one of the Blades, not the Same as as the Others. Stick with Mercury/Quicksilver. As for which Pitch, it would have been nice to know what rpm the 21 attained, so getting a new hub/insert would help establish that, and you could keep it as a Spare.
 

Rugglesworth

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Turning Point, IMHO, has had very poor QC in the past. I remember opening several Boxes, and finding one of the Blades, not the Same as as the Others. Stick with Mercury/Quicksilver. As for which Pitch, it would have been nice to know what rpm the 21 attained, so getting a new hub/insert would help establish that, and you could keep it as a Spare.
good to know thank you. Yeah I'm going to redo the hub this week and take it out to see where I'm at first. the 21P is what was recommended on the sea ray prop chart but again I'll be doing a lot of wakeboarding and tubing.
 

Scott06

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good to know thank you. Yeah I'm going to redo the hub this week and take it out to see where I'm at first. the 21P is what was recommended on the sea ray prop chart but again I'll be doing a lot of wakeboarding and tubing.
That is the best approach. Get wot rpm numbers with what you have. Likely going to a 19 three blade or an 18” 4 blade will give the results you want with out over revving on wot rpm. I had good luck in similar circumstances with michigan vortex 4 blades. Relatively cheap with good results
 

jimmbo

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Personally, I avoid 4 and 5 blade Props like the Plague, as they kill the Top End because of all the extra Drag, and that Drag is greater at all speeds so your Fuel Mileage takes a hit also
 

Scott06

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Personally, I avoid 4 and 5 blade Props like the Plague, as they kill the Top End because of all the extra Drag, and that Drag is greater at all speeds so your Fuel Mileage takes a hit also
Depends on how you use your boat. If top speed is your thing yes you don't want a 4 blade. If taking 6-7 people in you boat and going skiing or wakeboarding is then 4 blade can be an improvement in holeshot, stern lift and planning speed.

If you have a beamy stern heavy boat like mine I get slightly better top end with a Revolution 4 than an Enertia. I think my case is somewhat unique as this is because I can use full trim with the Rev 4 without blowing out. Conversely, you have a fairly light well powered boat...

When I tried a High five it was a waste of time.
 

JimS123

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It's an old boat with an old engine. The boat was intended for general use. It's not high performance or a speedboat. If the prop was truly the original, just replace it with a new one of the same kind.
 

Rugglesworth

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It's an old boat with an old engine. The boat was intended for general use. It's not high performance or a speedboat. If the prop was truly the original, just replace it with a new one of the same kind.
It's only got 359 hours and was garage kept it's entire life. Almost off the showroom floor. You can hardly hear it idling. If I can get a little more of a holeshot why not. I'll get the original one fixed up and see how it performs first however. Seems like it may be a pressed in hub though so I may need to just get another prop anyways
 

jimmbo

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Dropping Pitch and keeping 3 blades will improve the Holeshot, adding a Blade would also put more load on the Engine, likely killing Holeshot, unless the pitch is dropped even more
 

JimS123

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It's only got 359 hours and was garage kept it's entire life. Almost off the showroom floor. You can hardly hear it idling. If I can get a little more of a holeshot why not. I'll get the original one fixed up and see how it performs first however. Seems like it may be a pressed in hub though so I may need to just get another prop anyways
If you want better performance, with a prop change only, buy a SS Enertia. It won't be cheap, though. Use the Merc Prop selector tool to dial in the correct pitch, after you get the data from your existing repaired prop.

After 60 years of experimenting, THAT prop exceeded all my expectations.
 

Rugglesworth

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If you want better performance, with a prop change only, buy a SS Enertia. It won't be cheap, though. Use the Merc Prop selector tool to dial in the correct pitch, after you get the data from your existing repaired prop.

After 60 years of experimenting, THAT prop exceeded all my expectations.
Is there a way to cross reference this old merc model# 48 78122 A40 21P? Apparently it's listed as a 13.75"x 21P. So can I just find any prop with the same dimensions? I found a guy with a 13 7/8 x 21P lazer II stainless prop with a flo torq II hub for $300cad. I'm thinking it's pretty close to the same size but being stainless should I be looking for a 19P to compensate or would that matter?
 
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jimmbo

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If you have several Props, say 10, different makes or even models, but with the same Dia and Pitch, you can very well end up with 10 different outcomes. Other differences, such as Rake, Cupping, Blade Shape, Blade Area, between the Props will cause those differences.
 

Scott06

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Is there a way to cross reference this old merc model# 48 78122 A40 21P? Apparently it's listed as a 13.75"x 21P. So can I just find any prop with the same dimensions? I found a guy with a 13 7/8 x 21P lazer II stainless prop with a flo torq II hub for $300cad. I'm thinking it's pretty close to the same size but being stainless should I be looking for a 19P to compensate or would that matter?
if the laser has more cup or blade area then yes you would want to go down in pitch to stay at same rpm or improve hole shot.

As mentioned very much a trial and error thing, since you are new to this might be better to spend a little more to work with a prop shop or marina/dealer who will let you try before you buy. When I first started messing with props the semi local prop shop gave me two different pitches of Michigan Vortex 4 blades to try for a week. This was on a really under powered (3.0L) boat. Ended up keeping them both as the 16" was great for skiing, 18" worked great for everything else. Big improvement in planning and staying on a plane at lower speed.

When I got my current boat I saved searches on ebay and over two years was able to try 4 different props sold off what I didnt like.
 

Rugglesworth

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if the laser has more cup or blade area then yes you would want to go down in pitch to stay at same rpm or improve hole shot.

As mentioned very much a trial and error thing, since you are new to this might be better to spend a little more to work with a prop shop or marina/dealer who will let you try before you buy. When I first started messing with props the semi local prop shop gave me two different pitches of Michigan Vortex 4 blades to try for a week. This was on a really under powered (3.0L) boat. Ended up keeping them both as the 16" was great for skiing, 18" worked great for everything else. Big improvement in planning and staying on a plane at lower speed.

When I got my current boat I saved searches on ebay and over two years was able to try 4 different props sold off what I didnt like.
Definitely new to dialing in props, but I have been boating all of my life. Just lucky I didn't need to re prop in any of my old boats. The fact that I wasn't able to at least test this one puts me at a disadvantage. It's a press in hub on my old prop and I don't think it's worth being repaired as it's a little chwed up and over 22 years old. Where I live there are just overpriced Marine shops that won't let you try anything out and they are very unhelpful. I've had nothing but problems in the past.
 

Scott06

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Definitely new to dialing in props, but I have been boating all of my life. Just lucky I didn't need to re prop in any of my old boats. The fact that I wasn't able to at least test this one puts me at a disadvantage. It's a press in hub on my old prop and I don't think it's worth being repaired as it's a little chwed up and over 22 years old. Where I live there are just overpriced Marine shops that won't let you try anything out and they are very unhelpful. I've had nothing but problems in the past.
if you are new to it and can't try before you buy then cut your teeth playing with aluminum props.

I would think you can get yours repaired for about half of new cost. Properly repaired it will be good as new. If you go to the newer torq flo hub then I think you will need a different thrust washer. Be patient and get a baseline with the prop that is on there and make sure your tach is accurate.

I have used these guys when my semi local shop closed -


I would verify they can rehub them as some places dont do it anymore.

I think they also have a pitch exchange program or at least they used to where you can swap out to a different pitch of the same prop
 

Rugglesworth

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if you are new to it and can't try before you buy then cut your teeth playing with aluminum props.

I would think you can get yours repaired for about half of new cost. Properly repaired it will be good as new. If you go to the newer torq flo hub then I think you will need a different thrust washer. Be patient and get a baseline with the prop that is on there and make sure your tach is accurate.

I have used these guys when my semi local shop closed -


I would verify they can rehub them as some places dont do it anymore.

I think they also have a pitch exchange program or at least they used to where you can swap out to a different pitch of the same prop
I just talked to a prop guy at another big shop, says they don't do press in's anymore. My part number cross references to a 14.25x21p prop when the original was a 13.75 x 21p... Says a 12.75 x 20p high five would be good for towing and that a 13 7/8 x 21p stainless would work as well.... There are a couple high 5's in that range used here for 250-300 so I may just give one a shot
 

cyclops222

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Mar 21, 2024
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Web search Power Tech Props or Prop Gods They were both excellent.
More important is how efficient is the prop under load and speed.
Power Tech had a simple exchange program. Call them for prop advice when you are doing different loads. I have 2 props for different loads.
 

Scott06

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I just talked to a prop guy at another big shop, says they don't do press in's anymore. My part number cross references to a 14.25x21p prop when the original was a 13.75 x 21p... Says a 12.75 x 20p high five would be good for towing and that a 13 7/8 x 21p stainless would work as well.... There are a couple high 5's in that range used here for 250-300 so I may just give one a shot
My trial with a high five I thought it was junk got on plane fast refs went way up boat went no where. Took it out twice and sold it


Much better water sports performance with revolution 4 and Vensura/offshore
 
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Rugglesworth

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My trial with a high five I thought it was junk got on plane fast refs went way up boat went no where. Took it out twice and sold it


Much better water sports performance with revolution 4 and Vensura/offshore
also good to know thank you, do you remember what size prop the high 5 was?
 
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