What prop are you running on your 17-19ft boat w/ Merc 3.0

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I have a 1988 Wellcraft 180 Classic w/ Merc 3.0, Alpha 1.

My prop has no casting to indicate pitch. I'm fairly sure I'm propped wrong and want to see what others are using. Plus the prop that came with the boat is beat up.

3 blade, unknown pitch, 4600 RPM, 33 MPH, Cruising at 24 mph @ 3300 RPM.

Pitch/WOT RPM/ MPH, Cruising speed & RPM
 
i had a Stingray boat similar to that and i would be able to get 42-43 out of a 120 IO

17 pitch Stainless. Also get it Balanced and Blueprinted by Brett at B Blades. It will make a world of difference.
 
It should be stamped on a blade or in the hub. Your correct prop is more about rpm at WOT full throttle. . It shouldn't be past the red line on the tach at full bore . IBoats has a good site to look your likely prop range up. Remember, which prop depends on what you're planning on doing , wakeboarding vs cruising It's not an exact science.
Keep in mind you can usually get the old one fixed for a spare. The guy that fixes em for all the marinas usually is in the yellow pages as Prop repair.. he will often work at the local steel fab shop and specialize in AL welding. aside from the TIG welder he will have the magic book. It lists every prop under the sun, boats, weights, engines on and on... if you can't quite figure out which one best fits your needs or aren't sure that's the guy to look up rather than a marina. All the props they fix for customers are usually done by him and marked up for their cut afterwards so go straight to the source.
 
On fixing props- it is usually not cost effective to repair an aluminum prop: make sure to check prices for new vs rebuild. For stainless steel (or bronze / Nibral etc) then it makes sense to rebuild. It all depends on the labor price in your area.
 
Repair cost is about half the price of new. Last one I had done was $65. New one around 130-150 last I looked. That's for a similar type for my 4.3 Mercruiser. Like I said go to the guy who actually does the work and avoid that extra from the marina.
If the OP goes new consider switching the to the newer style with the hollow center and plastic insert instead of the rubber center hub. They're cheaper to replace. Depending on the year he might have it anyway. These things are why I say go to the prop guy directly. He can tell you more about what you want / need than you can think to ask. Also he might let you try out a couple and see what works best for you and just return the other after.
 
Originally Posted by dja4260
I have a 1988 Wellcraft 180 Classic w/ Merc 3.0, Alpha 1.

My prop has no casting to indicate pitch. I'm fairly sure I'm propped wrong and want to see what others are using. Plus the prop that came with the boat is beat up.

3 blade, unknown pitch, 4600 RPM, 33 MPH, Cruising at 24 mph @ 3300 RPM.

Pitch/WOT RPM/ MPH, Cruising speed & RPM


Here is a suggestion keeping in mind we are talking different hull types and brands.

We have a new to us, barely used, mint, Chapparal 180 SSI with VolvoPenta 3.0 (same gm engine block as the merc) of course different outdrive.
However the prop was dinged up, been boating my whole life and played around with props for best all around performance.

I read up alot on the prop I am going to mention because of the following;

Chaparral, being a higher end respectable (as GW) manufacturer specifically mated this prop to the 180SSI with the 3.0 block and it came on everyone of their boats even though it cost more because they, being respectable, wanted the best performance out of the 3.0 engine.

After reading all this, I decided, for the first time, maybe in my life, to trust the manufacturer and I purchased a new OEM VolvoPenta 4 blade prop that Chaparral sold with this boat, in order to get the best performance out of the 3.0. Just the fact that Chaparral chose a more expensive 4 blade prop over a 3 impressed me.

Anyway, of course, we are talking two different hulls and styles of boats, just wanted to give you something to think about.
We are blown away with the performance of this prop, 4 adults on a 18 foot boat and it planes quickly will run up close to 4800 RPM @ 44MPH, which I think at that point maybe rev limited, FYI, we do not run full throttle, just testing it. Cruise around 3500 wish I could tell you speed, forgot, our lake is so big here that by middle of the day you can go much faster without banging around anyway.

Hope this helps some, but I think maybe back in 1988 boats were more heavy and a GW, lets face it is built like a tank. Our hull uses a lighter kelvar.
This is what we use, Im sure Merc had a branded one the same.

Volvo Penta SX Stern Drive New OEM Propeller 14x21 Prop 3587524 4 Blade RH 19spl

I cant tell you in words how impressed we are with the way the boat performs with this prop, had my bother and sis in law out with us, even he was shocked, boating his whole life to, we both owned boats anywhere from 18 feet to 29 feet for decades and he couldnt get over how well it ran loaded with 4 adults and gear with a 3.0, he thought it would be a dog and I was concerned as well but I couldnt turn my back on the deal when I saw this boat at the end of winter and why I bought it.
Boy I am glad I did, far exceeded what I expected from this engine.

BTW, first volvoPenta for me, every boat we owned previous was a merc or twin mercs
 
Last edited:
Originally Posted by alarmguy
Originally Posted by dja4260
I have a 1988 Wellcraft 180 Classic w/ Merc 3.0, Alpha 1.

My prop has no casting to indicate pitch. I'm fairly sure I'm propped wrong and want to see what others are using. Plus the prop that came with the boat is beat up.

3 blade, unknown pitch, 4600 RPM, 33 MPH, Cruising at 24 mph @ 3300 RPM.

Pitch/WOT RPM/ MPH, Cruising speed & RPM


Here is a suggestion keeping in mind we are talking different hull types and brands.

We have a new to us, barely used, mint, Chapparal 180 SSI with VolvoPenta 3.0 (same gm engine block as the merc) of course different outdrive.
However the prop was dinged up, been boating my whole life and played around with props for best all around performance.

I read up alot on the prop I am going to mention because of the following;

Chaparral, being a higher end respectable (as GW) manufacturer specifically mated this prop to the 180SSI with the 3.0 block and it came on everyone of their boats even though it cost more because they, being respectable, wanted the best performance out of the 3.0 engine.

After reading all this, I decided, for the first time, maybe in my life, to trust the manufacturer and I purchased a new OEM VolvoPenta 4 blade prop that Chaparral sold with this boat, in order to get the best performance out of the 3.0. Just the fact that Chaparral chose a more expensive 4 blade prop over a 3 impressed me.

Anyway, of course, we are talking two different hulls and styles of boats, just wanted to give you something to think about.
We are blown away with the performance of this prop, 4 adults on a 18 foot boat and it planes quickly will run up close to 4800 RPM @ 44MPH, which I think at that point maybe rev limited, FYI, we do not run full throttle, just testing it. Cruise around 3500 wish I could tell you speed, forgot, our lake is so big here that by middle of the day you can go much faster without banging around anyway.

Hope this helps some, but I think maybe back in 1988 boats were more heavy and a GW, lets face it is built like a tank. Our hull uses a lighter kelvar.
This is what we use, Im sure Merc had a branded one the same.

Volvo Penta SX Stern Drive New OEM Propeller 14x21 Prop 3587524 4 Blade RH 19spl

I cant tell you in words how impressed we are with the way the boat performs with this prop, had my bother and sis in law out with us, even he was shocked, boating his whole life to, we both owned boats anywhere from 18 feet to 29 feet for decades and he couldnt get over how well it ran loaded with 4 adults and gear with a 3.0, he thought it would be a dog and I was concerned as well but I couldnt turn my back on the deal when I saw this boat at the end of winter and why I bought it.
Boy I am glad I did, far exceeded what I expected from this engine.

BTW, first volvoPenta for me, every boat we owned previous was a merc or twin mercs


Thank you for the feedback. I found out my prop is a beat up 14x19 pitch. I'm glad to hear that you can pull a 21 pitch. My boat is heavier as Wellcraft makes good stuff and it's older. I grew up on a 23 ft Chaparral. It was a well built, quality boat!
 
Originally Posted by dja4260
I have a 1988 Wellcraft 180 Classic w/ Merc 3.0, Alpha 1.

My prop has no casting to indicate pitch. I'm fairly sure I'm propped wrong and want to see what others are using. Plus the prop that came with the boat is beat up.

3 blade, unknown pitch, 4600 RPM, 33 MPH, Cruising at 24 mph @ 3300 RPM.

Pitch/WOT RPM/ MPH, Cruising speed & RPM

Unless someone has the exact same boat and set up this is not the way to determine proper prop. Bring your old one in and have a boat mechanic identify it. Then shoot for a 3.0 recommended WOT rpm. I believe the 3.0 should fall in the 4200-4600 level. Sounds like a small step up in pitch or diameter would help. One other idea is to see what prop came with the boat from the factory, if you can even find that info.
 
A place that can repair can also tell you the pitch. You can get AL props repitched (slightly) and/or cupped.

You will probably need between a 17 and 19 pitch. Get a good known pitch prop, half a gas tank, just driver and go at WOT. If the RPM will be above the max for engine get higher pitch. If below then less pitch. Don't go too crazy if you are close.

SS flexes less and is a better prop. But hit something with an SS prop and you may take out your outdrive. With AL it will just chew up the prop.
 
Also, different manufacturers measure pitch differently so a Quicksilver 17p may be slightly different that a Michigan Wheel or, in my case Solas, so the numbers are not a direct comparison. Best to get actual user feedback as you are doing and/or try different props on similar hulls yourself.


We have a Chaparral 183ss w/ the 4.3 Merc. It came with a 21p 3 blade which was OK on pick up and plane, but was a great cruiser. Being as we are on a smaller lake and primarily use the boat for tubing and slow cruise, as well as having to transit a narrow canal, I went for a 4 blade 17 or 18 pitch prop. This gave lower plane speed, better launch and pull, and better low speed handling at the expense of a top end we'd never use.
 
Quote
Plus the prop that came with the boat is beat up.


THIS is the key! You may have the correct prop but it is far from operating efficiently. Also boat speedos are notoriously incorrect.
 
I know the pitch. It's a 14x19 pitch prop. Yesterday with 4 adults and 4 kids I used to GPS to establish 28 mph @ 4000 rpm, 23 mph @ 3400 rpm. I could pass the 4600 MAX rpm with a full load of people and gas on board. I'd like to try a 21 pitch as I feel that I could pull it.
 
If your current prop was in perfect shape then the 21" pitch move would be on the money. Since you have said it is "beat up" you can't rely on the numbers you are getting. If possible try a perfect 19" P and use those numbers to judge by.
 
18 foot Marada with 3.0LX. Currently 3 blade, 19 pitch. Tried a 21 pitch, but would not get to WOT. I did use a 4 blade composite 19 pitch and that was the bomb. But, hit a rock and the thing just blew up so back to the aluminum 19 pitch. I think that's a good compromise for top end and pulling tubes and skiers.
 
Originally Posted by Schmoe
18 foot Marada with 3.0LX. Currently 3 blade, 19 pitch. Tried a 21 pitch, but would not get to WOT. I did use a 4 blade composite 19 pitch and that was the bomb. But, hit a rock and the thing just blew up so back to the aluminum 19 pitch. I think that's a good compromise for top end and pulling tubes and skiers.


Great to know! Thank you for the insight.
 
I don't have an inboard but I have had great luck with Turning Point Propellers.
https://turningpointpropellers.com/

I currently own a 17 and 19 pitch and it is, by far, the best thing I ever did for this engine.

Better holeshots, way less cavitation and into the required rpm range all for $150 dollars CDN.

If you haven't purchased one yet, have a look at them first. I purchased the Hustler's and like their ads read, I believe I got SS performance from an aluminum prop.

SDC10031 (Large).JPG
 
Originally Posted by dja4260
I have a 1988 Wellcraft 180 Classic w/ Merc 3.0, Alpha 1.

My prop has no casting to indicate pitch. I'm fairly sure I'm propped wrong and want to see what others are using. Plus the prop that came with the boat is beat up.

3 blade, unknown pitch, 4600 RPM, 33 MPH, Cruising at 24 mph @ 3300 RPM.

Pitch/WOT RPM/ MPH, Cruising speed & RPM



I just sold my 85, 3.0l in a aggressive deep v century hill, 19 foot.

The mph you just described was with a 19 pitch 3 blade.

My everything prop was a 21 pitch. 24mph at 3k rpm. Close to 30 at 3500rpm. I had a 23 pitch prop on it for a small amount of time before being stolen. I loved it. I wanted to try a 25 pitch but I sold the boat.

If you cruise a lot, around 3k rpm, 21 or 23 pitch 3 blade's will do you well. And your fuel economy will be tremendous
 
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