Evinrude 130HP switching from 3 blade to 4 blade

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
Hi,
I'm currently running a 3 blade 14.5" x 19" stock standard ss prop on an Evinrude 130HP v6 gearbox, pushing a fibreglass deep vee fishing boat (approx 2,200lb). I get 6,000RPM and 35-38kts @ WOT.
My reasons for thinking about a 4 blade prop are 1) sit on the plane at lower RPM (currently 3,500RPM is my minimum), and 2) better fuel economy and speed at mid-range RPM which is where i spend most of the time.
I am looking at a Solas HR4 14.25" x 17".
Any advise / thoughts or conerns going from a 3 blade to a 4blade as described above?
Is there enough grunt for the 130HP to swing the 4blade in question?
Appreciate your help
cheers
aok47
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,414
Every boat is different therefore your results may vary.

I went from a four to a three blade and all aspects of my performance improved.

Adding friction reduces efficiency. I gained 10% going back to a 3 blade

A hulls planing speed is a function of hull geometry. I have yet to see verifiable data to support the claim of reduced planing speeds with a four blade prop.

You reduce diameter to maintain “grunt” if need be.

Unless you have a particular problem to solve, 4 blade props are rarely the answer to general all around use
 

Scott06

Vice Admiral
Joined
Apr 20, 2014
Messages
5,542
Hi,
I'm currently running a 3 blade 14.5" x 19" stock standard ss prop on an Evinrude 130HP v6 gearbox, pushing a fibreglass deep vee fishing boat (approx 2,200lb). I get 6,000RPM and 35-38kts @ WOT.
My reasons for thinking about a 4 blade prop are 1) sit on the plane at lower RPM (currently 3,500RPM is my minimum), and 2) better fuel economy and speed at mid-range RPM which is where i spend most of the time.
I am looking at a Solas HR4 14.25" x 17".
Any advise / thoughts or conerns going from a 3 blade to a 4blade as described above?
Is there enough grunt for the 130HP to swing the 4blade in question?
Appreciate your help
cheers
aok47
What is the recommended WOT rpm for your engine? If you are close or at the top now I would think dropping 2" in pitch and adding the 4th blade would keep you relatively close to where you are now .

I have run 4 blades on my last two boats really like what they do for all aspects of boating ( yes you loose some top end ...)
 

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
What is the recommended WOT rpm for your engine? If you are close or at the top now I would think dropping 2" in pitch and adding the 4th blade would keep you relatively close to where you are now .

I have run 4 blades on my last two boats really like what they do for all aspects of boating ( yes you loose some top end ...)
recommended top end RPM range per the service manual is 5,000-6,000RPM
Thanks for sharing your thoughts!
AK
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Hi,
I'm currently running a 3 blade 14.5" x 19" stock standard ss prop on an Evinrude 130HP v6 gearbox, pushing a fibreglass deep vee fishing boat (approx 2,200lb). I get 6,000RPM and 35-38kts @ WOT.
My reasons for thinking about a 4 blade prop are 1) sit on the plane at lower RPM (currently 3,500RPM is my minimum), and 2) better fuel economy and speed at mid-range RPM which is where i spend most of the time.
I am looking at a Solas HR4 14.25" x 17".
Any advise / thoughts or conerns going from a 3 blade to a 4blade as described above?
Is there enough grunt for the 130HP to swing the 4blade in question?
Appreciate your help
cheers
aok47
I run like you do. I replaced a 3 blade Laser II with the Solas 4 blade dropping one inch in pitch. The solace performed beautifully and I have no aspirations to take it off. Go for it.
 

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
Thanks for the sharing everyone.
I'm going to try the 4blader (found a new secondhander at 1/3rd the price of store new) and i'll report back on performance.
 

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
Tested 3 props in the same conditions one after the other
3 bladed OMC aluminium 14 1/2" x 19" brand new, 3 blade OMC stainless 14 1/2" x 19" in good condition but been repaired in the past, 4 blade SOLAS HR4 stainless 14 1/4" x 17" brand new.
Note that there were some fluctuations in readings so i had to mentally average the numbers before recording them.

Results below, each dot is a recorded data point:
1638073036308.png1638073078574.png
1638072980312.png


Observations from boat handling...
4bladed prop lifted the stern of the boat, very smooth and noticeably less vibration throughout the RPM range, could make very tight turns with motor trimmed out compared to other 2 props.

Unfortunately with the 4bladed prop it didn't manage to have the boat on the plane at a lower RPM and no improvement in the fuel economy either compared tot he 3 blade stainless (i'm assuming the dip in km/ltr at 5,000RPM for the 4blader is a recording error on my part)

Anyway, thought i would share for those interested.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,414
Tested 3 props in the same conditions one after the other
3 bladed OMC aluminium 14 1/2" x 19" brand new, 3 blade OMC stainless 14 1/2" x 19" in good condition but been repaired in the past, 4 blade SOLAS HR4 stainless 14 1/4" x 17" brand new.
Note that there were some fluctuations in readings so i had to mentally average the numbers before recording them.

Results below, each dot is a recorded data point:
View attachment 353227View attachment 353228
View attachment 353226


Observations from boat handling...
4bladed prop lifted the stern of the boat, very smooth and noticeably less vibration throughout the RPM range, could make very tight turns with motor trimmed out compared to other 2 props.

Unfortunately with the 4bladed prop it didn't manage to have the boat on the plane at a lower RPM and no improvement in the fuel economy either compared tot he 3 blade stainless (i'm assuming the dip in km/ltr at 5,000RPM for the 4blader is a recording error on my part)

Anyway, thought i would share for those interested.
Some of it doesn’t make sense
What order curve did you use?
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Lots of myths and ideas on 4 blades out there. Some for the good and others for the worse. They have their place for some things. No doubt. But I really think that befkre doing so…you need to think if it’s not an issue you can solve with a 3 blade.
For this I’d suggest that a solas prop of any sort is about as cheap as they get. So some seeing improvements over a 3 blade when going to one, may have had a pretty poor 3 blade to start with. The only 4 blades I know of that have a chance of improvement over a normal 3 blade would be things like a Rev 4 or bravo. Trophy perhaps too. But these wouldn’t compare to the 3 blade props like tempest or enertia pehaps like for like. Unless the set up you have specifically s rarely might benefit from their attributes. It should also be known that the idea of a 4 blade dropping rpm over a 3 blade also depends on what 3 and 4 blade being discussed. All that aside. It’s still always the case that props on a boat will always be an unknown until they are tried. The only thing that can’t be argued with is the one rule that stays true. The less blades on a prop…the more efficient it is. This can’t be argued with. When comparing like for like.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Lots of myths and ideas on 4 blades out there. Some for the good and others for the worse. They have their place for some things. No doubt. But I really think that befkre doing so…you need to think if it’s not an issue you can solve with a 3 blade.
For this I’d suggest that a solas prop of any sort is about as cheap as they get. So some seeing improvements over a 3 blade when going to one, may have had a pretty poor 3 blade to start with. The only 4 blades I know of that have a chance of improvement over a normal 3 blade would be things like a Rev 4 or bravo. Trophy perhaps too. But these wouldn’t compare to the 3 blade props like tempest or enertia pehaps like for like. Unless the set up you have specifically s rarely might benefit from their attributes. It should also be known that the idea of a 4 blade dropping rpm over a 3 blade also depends on what 3 and 4 blade being discussed. All that aside. It’s still always the case that props on a boat will always be an unknown until they are tried. The only thing that can’t be argued with is the one rule that stays true. The less blades on a prop…the more efficient it is. This can’t be argued with. When comparing like for like.
"The less blades on a prop…the more efficient it is. This can’t be argued with. When comparing like for like."

That's why Karl equipped his engines with 2 blade props with lots of surface area....till the Phantom Black paint and 3 blades, Merc. 1000 first production 100 hp 2 stroke outboard. Had a friend with one and for the day, quite a performer.

Obviously he couldn't go any lower than 2 and that and their "said to be" over powered for the rating engines, ran circles around the competition....even the little powerhouse 12 hp, to name an OMC tamer, he marketed for Western Auto auto parts stores that sold Merc engines under the Wizard badge.

I bought a new 25 when I was a teenager for $400; a spinoff of the Mark 30, 30 hp.. Had one on display in the WA widow...lusted in my heart every time I passed that store. Worked all summer mowing lawns to earn enough money to buy it....I think yards went for $3 back then and you pushed your mower and gas can down the street looking for yards needing mowing. Usually a knock at the door (moms were at home then) got you the job.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
"The less blades on a prop…the more efficient it is. This can’t be argued with. When comparing like for like."

That's why Karl equipped his engines with 2 blade props with lots of surface area....till the Phantom Black paint and 3 blades, Merc. 1000 first production 100 hp 2 stroke outboard. Had a friend with one and for the day, quite a performer.

Obviously he couldn't go any lower than 2 and that and their "said to be" over powered for the rating engines, ran circles around the competition....even the little powerhouse 12 hp, to name an OMC tamer, he marketed for Western Auto auto parts stores that sold Merc engines under the Wizard badge.

I bought a new 25 when I was a teenager for $400; a spinoff of the Mark 30, 30 hp.. Had one on display in the WA widow...lusted in my heart every time I passed that store. Worked all summer mowing lawns to earn enough money to buy it....I think yards went for $3 back then and you pushed your mower and gas can down the street looking for yards needing mowing. Usually a knock at the door (moms were at home then) got you the job.
Love hearing and reading things like this Texas. Just brilliant. I know of some classic half century old U.K. ski boats with 2 blades still on them.
 

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
Some of it doesn’t make sense
What order curve did you use?
just a scatter plot in Excel.
Like i said i had to mentally average some of the data points because there was variation...
Cheers
AK
 

aok47

Seaman
Joined
Apr 18, 2004
Messages
50
Lots of myths and ideas on 4 blades out there. Some for the good and others for the worse. They have their place for some things. No doubt. But I really think that befkre doing so…you need to think if it’s not an issue you can solve with a 3 blade.
For this I’d suggest that a solas prop of any sort is about as cheap as they get. So some seeing improvements over a 3 blade when going to one, may have had a pretty poor 3 blade to start with.
Yep, i've since realised :) . For the price i paid it was worth trying.
Hopefully by posting test data (acknowledging the limitations and mental averaging I had to do) on forums like this it'll give the next guy more info to go on when making the decision on what to try...
I'll keep an eye out of higher performance 3 blade props mentioned

Thanks for all the comments and knowledge sharing!
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Yep, i've since realised :) . For the price i paid it was worth trying.
Hopefully by posting test data (acknowledging the limitations and mental averaging I had to do) on forums like this it'll give the next guy more info to go on when making the decision on what to try...
I'll keep an eye out of higher performance 3 blade props mentioned

Thanks for all the comments and knowledge sharing!
No worries. If it helps you any. I’ve found a huge difference in ability between props, in terms of your idea of sitting on the plane with less rpm. Quick example. I have an enertia 20” 3 blade for one of my boats and a tempest 19” 3 blade. Despite the enertia being more pitch…the tempest plus sits on the plane happier at lower rpm and better fuel economy (at same speed) than the enertia. The reason for this is the much bigger blades and more diameter on the tempest. The enertia needs more speed to stay happy on the plane. The rpm at the top end are remarkably similar too. The enertia is only about a mph or 2 at best quicker top end. But all the way through the rpms…the big tempest is better on fuel and ability.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Love hearing and reading things like this Texas. Just brilliant. I know of some classic half century old U.K. ski boats with 2 blades still on them.
Ski boats around here, including Ski-Nautique use 3 blade bronze. Old period Chris Craft and such running Greymarine 6 bangers ran 3s also. Never saw one with a 2 blade...but that's here and you are there. As the old TV show goes: "Different Strokes for Different Folks". Grin
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Plot ”real” data then use a polynomial or logarithmetic 3rd order trend line to average out the results. Much, much more accurate than fudging numbers mentally.
OT...... in following along with your postings over the years, for a guy who apparently has an advanced degree or so in engineering or math, your Avatar/Handle just blows me away. Apparently you quit the rat-race and decided to do what you love. Good for you.
 
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