Good prop for 1991 2050 Bayliner 5.0

[rstro67]

Does anyone have a suggestion on a good prop for a 1991 2050 Bayliner 5.0. I have recently purchased the boat and it has a 13 inch 21 pitch 3 blade aluminum prop. It is useable, but when I run wot the rpms went up over 5000, so I had to back it off. This works fine for wakeboarding and tubing, but it seems like I should also be getting a better hole shot than I am.

 

[SparkieBoat]

Re: Good prop for 1991 2050 Bayliner 5.0

get a 15P 3 blade or a 13P 4 blade and a set of trim tabs. you will be very happy.

 

[rstro67]

Re: Good prop for 1991 2050 Bayliner 5.0

Sounds like a pretty small pitch, what kind of top end would you get with that setup. I was going about 45 when I realized I was over revving.

 

[bnicov]

Re: Good prop for 1991 2050 Bayliner 5.0

Check to see what your operating range for max RPMs are. 2 inches of pitch means about 200rpms. So, if you drop down to a 17p prop, you should be running around 4600rpms. Your hole shot will be much better but you will lose around 4mph on top speed, a good tradeoff since you do tubing with the boat.

 

[rstro67]

Re: Good prop for 1991 2050 Bayliner 5.0

That sounds about like what I am looking for. I don't mind losing a little top speed, I don't go there very often anyway. Any thoughts on a 3 vs 4 blade prop?

 

[craze1cars]

Re: Good prop for 1991 2050 Bayliner 5.0

None of the recommendations given so far make any sense whatsoever....I'm guessing they must have misread your question....so far its just seems like random numbers are being thrown about, and the recommendations are the exact opposite of what you need to do.

Currently you're spinning more than 5,000 rpms with a 21 pitch prop. This is too fast. You slow a motor down by ADDING pitch, not subtracting pitch. So I have no idea where these recommendations for 15, 13, and 17 pitch props are coming from, and they are flat-out wrong....if you put any one of those props on your motor and your tach will exceed 6,000 and you'll likely cause damage to motor and/or outdrive. Of course your holeshot will be spectacular....

You probably need a 23. But this assumes your data is correct....and I somehow doubt it. I find it hard to believe you can exceed 5,000 rpm, but are still disappointed with your holeshot. Your holeshot won't get any better than it is now while you are seemingly underpropped....

What is your outdrive gear ratio? And what is your top speed when you're running 5,000 rpms? You reported about 45...with that data a prop slip calculator can be utilized to tell you if maybe your tach is incorrect, or you are mis-reporting your pitch, or if your outdrive has a non-stock gear ratio. This is all critical info to know for prop selection. If I assume 1.62, typical for a 5.0, you should be running somewhere around 50 to 57 mph at 5,000 rpm at normal slip. Your reported 45 gives us 26% slip...which is an awful high number, and enough to make me suspect some of your data. Is it possible your tach is inaccurate?, or is my assumption of 1.62 ratio wrong? If your data points are indeed accurate, then I revert to recommending a 23 pitch prop, depending on what exactly you have now, and what your goals are....

For everyone's info, the operating range of this engine is most likely 4,200 to 4,600....can the owner confirm? So far we don't even know the make make/model of the motor in question...I am assuming Volvo, OMC, or Mercruiser sterndrive. All of those should be in that operating range for that vintage.

 

[John_S]

Re: Good prop for 1991 2050 Bayliner 5.0

None of the recommendations given so far make any sense whatsoever....I'm guessing they must have misread your question....so far its just seems like random numbers are being thrown about, and the recommendations are the exact opposite of what you need to do.

Currently you're spinning more than 5,000 rpms with a 21 pitch prop. This is too fast. You slow a motor down by ADDING pitch, not subtracting pitch. So I have no idea where these recommendations for 15, 13, and 17 pitch props are coming from, and they are flat-out wrong....if you put any one of those props on your motor and your tach will exceed 6,000 and you'll likely cause damage to motor and/or outdrive. Of course your holeshot will be spectacular....

You probably need a 23...or even a 25. But this assumes your data is correct....and I somehow doubt it. I find it hard to believe you can exceed 5,000 rpm, but are still disappointed with your holeshot. Your holeshot won't get any better than it is now while you are seemingly underpropped....

What is your outdrive gear ratio? And what is your top speed when you're running 5,000 rpms? With that data a prop slip calculator can be utilized to tell you if maybe your tach is incorrect, or you are mis-reporting your pitch, or if your outdrive has a non-stock gear ratio. This is all critical info to know for prop selection. If I assume 1.62, typical for a 5.0, you should be running somewhere around 50 to 57 mph at 5,000 rpm. Is that correct? If no, then one of your data points is wrong (bad tach?), or my assumption of 1.62 ratio is wrong. If your boat IS capable of going that fast, then your data points are accurate, and I revert to recommending a 23 or 25 pitch prop, depending on what exactly you have now and what your goals are....

For everyone's info, the operating range of this engine is most likely 4,200 to 4,600....can the owner confirm? So far we don't even know the make make/model of the motor in question...I am assuming Volvo, OMC, or Mercruiser sterndrive. All of those should be in that operating range for that vintage.

C1C is correct. Something is amiss and need more data. I don't remember if Bayliner switched over to Mercruiser by '91 or still had OMC. Given its a 5.0L it at least is not a dreaded L-drive.

I suspect the prior posters mis-read the 13" diameter as the pitch. A 13" diameter by the way is small for a typical outdrive on a Bayliner 2050.

 

[SparkieBoat]

Re: Good prop for 1991 2050 Bayliner 5.0

John is right, I misread the post, I was basing it from a 13P prop currently on the boat not the actual 21P that really is on the boat..but the same principle will apply..add 2 pitches and a set of trim tabs, hence a 23P. trim tabs will make a huge difference in the hole shot..or if you want a 4 blade go with a 22P, . and go with a 14+ diameter unless its a 4 blade. I apologize for any confusion, I blame it on my wife for pestering me to get off the computer...LOL

 

[rstro67]

Re: Good prop for 1991 2050 Bayliner 5.0

The engine is a Mercruiser, and I have an alpha one outdrive. I have only owned the boat for 1 week, it is possible that the tach is off. How would a larger diameter prop with a lower pitch affect the performance?

 

[bnicov]

Re: Good prop for 1991 2050 Bayliner 5.0

Now that I have read what I wrote, I have egg on my face!! I went the wrong way!!! You'd need a 25p prop to get down to 4600rpm. I'd think about a 21p 14" 4bladed prop or a 23p in the same size 4 blade to help with the holeshot. You should get your tach verified against a shop tach to see if it's accurate.

 

[craze1cars]

Re: Good prop for 1991 2050 Bayliner 5.0

How would a larger diameter prop with a lower pitch affect the performance?

Diameter is secondary to pitch by a long shot....so a larger diameter prop with a lower pitch would spin your motor FASTER. You don't want that.

I say don't worry about diameter, just shop by pitch. Most props for a boat of that size will be in the 14-ish range so your diameter will be coming up a little bit anyway. 4 blade is usually better than 3 blade for holeshot, which is one of your priorities....so I'd be shopping 4 blade, probably in a 23, if I were you, and IF your data is 100% correct. And I STRONGLY suggest test-driving a prop before mail-ordering. Especially since you have never actually gone full speed and you admit you had to back out of it when you get up past 5,000....

And I'll repeat again that your slip figures don't jive very well but it's based on some incomplete data...we still need to know your drive ratio to confirm.

So I actually say you should do things in this order: 1. Confirm your drive ratio and confirm your tach's accuracy, and 2. only THEN maybe start shopping for a prop. Otherwise you may purchase the wrong prop entirely...or not need one at all.

 

[John_S]

Re: Good prop for 1991 2050 Bayliner 5.0

I looked at the prop slip numbers for all the common merc ratios that could have been stock: 1.5, 1.63, and high altitude 1.82. Still way too much slip. Tach, speed, or both are wrong or you are cavtiting. Maybe someone stuck a 3.0L alpha drive on it? A 2.0 ratio or higher would start to make sense out of the numbers. If that is the case, you probably want to get the gear ratio changed vs going to 23-25" pitch.


PS: The Bayliner online parts manual for your model was not available on the Bayliner site. That would list the engine drive pkg options and what the stock prop was. My '97 2050 called for a 15" diameter. The 13" is too small, and you are getting some slip from it, but it is not the main issue. What ever prop you decide to try, go up to at least a 14" diameter.

 

[Tail_Gunner]

Re: Good prop for 1991 2050 Bayliner 5.0

I looked at the prop slip numbers for all the common merc ratios that could have been stock: 1.5, 1.63, and high altitude 1.82. Still way too much slip. Tach, speed, or both are wrong or you are cavtiting. Maybe someone stuck a 3.0L alpha drive on it? A 2.0 ratio or higher would start to make sense out of the numbers. If that is the case, you probably want to get the gear ratio changed vs going to 23-25" pitch.


PS: The Bayliner online parts manual for your model was not available on the Bayliner site. That would list the engine drive pkg options and what the stock prop was. My '97 2050 called for a 15" diameter. The 13" is too small, and you are getting some slip from it, but it is not the main issue. What ever prop you decide to try, go up to at least a 14" diameter.

Bingo

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