Will a 4-Blade Really Help?!

[Bartableman7]

I have a 1980 50 HP 4 cylinder 2-stroke on my 18 foot fiberglass bass boat. It planes up and cruises at 30 mph max. Fine since I'm just fishing from spot to spot. I ask the Mercury marine mechanic if a 4 blade will help me get up on plane quicker and stay at a slower speed. He said that's witchcraft crap and I wouldn't notice any difference. Whhaaaat? How about any extra opinions? Thoughts....

 

[Scott F]

I don't know about a four blade prop, but a hydrofoil should help you get on plane faster and stay on plane at slower speeds. It may cost you a mile or two of top end, but it will also help save on gas. 

[Logan S]

Some 4-blades will have better holeshot...But 50hp on a an 18' glass bass boat is underpowered and your mechanic is probably right that a different prop won't help simply becasue the horsepower isn't there to make enough of a difference.

 

The blade configuration is only one aspect too...Pitch, diameter, and venting are all big factors on the holeshot.  Different props have different combinations of these attributes so it's not just 3-blade vs 4-blade.

[Way2slow]

I think it depends on the hull and motor.  I personally have never seen an advantage with the couple of four blades I've tried over the years.  Actually, I've always run custom tuned performance props and the few four blades I have tried didn't hold a candle to the three blades I run.

As mentioned, to get the most bang for the buck, install a Sport SE200 hydrofoil.  I think the 200 is the size a 50 runs.  That's absolutely the best money you can spend if hole shot is an issue.   I run the SE300 on my 300+hp hotrod motors, not because I need it, but because my 20' Javelin literally leaps out of the water like a drag boat  with them.

[DINK WHISPERER]

I agree that a hydrofoil will help some moreso than a different prop. And I DEFINITELY agree that it's really underpowered. My 18 1/2ft with a 150hp needed some playing with to get the plane speed I wanted. So a 50hp will struggle a lot. 

[WRB]

18' heavy glass boat powered with a 37 year old 50 hp outboard you are lucky if it gets enough speed to up on plane! You are seriously underpowered.

Back to your question, everything being equal like pitch and diameter a 3 blade prop gets to higher rpm's faster than a 2 blade, a 4 blade faster than a 3 blade. It's not witchcraft it's about higher rpm's at slower forward speed, like gears in transmission or bicycle.

Do you know what pitch/diameter and prop material (aluminum) you have and what condition it's in after 30+ years of use??

Tom

[Scott F]

One thing to remember, back in 1980, glass boats were much lighter than they are today. While I'm sure the boat the OP has is underpowered, the 50 he has now which would not get a modern boat on plane, probably has been there a long time. Repowering a boat that will be 40 years old soon is probably not a good investment compared to a $50 hydrofoil. 

[slonezp]

Only guys I know running 4 blades are fishing big water rough conditions or pulling skiers/tubes. The 4 blade give you more bite at lower speed under adverse conditions.

[Catt]

Nauticus Smart Tabs ?

 

 

 

[PECo]

My 2017 Triton 179 TrX with Mercury 115 Pro XS four-stroke came with a three-blade prop. The boat felt a little sluggish out of the hole, so I swapped out the prop with a Mercury Spitfire X7 four-blade prop.

 

The difference was like night and day. Now, the boat comes smoothly out of the hole and accelerates more linearly. With a full tourney load, 450 pounds of fishermen, 26 gallons of fuel and a full 36 gallon livewell, it'll still run at least 45 miles per hour.

[Russ E]

3 minutes ago, PECo said:

My 2017 Triton 179 TrX with Mercury 115 Pro XS four-stroke came with a three-blade prop. The boat felt a little sluggish out of the hole, so I swapped out the prop with a Mercury Spitfire X7 four-blade prop.

 

The difference was like night and day. Now, the boat comes smoothly out of the hole and accelerates more linearly. With a full tourney load, 450 pounds of fishermen, 26 gallons of fuel and a full 36 gallon livewell, it'll still run at least 45 miles per hour.

Thats pretty good. i have a ranger z175 I think it is similar to the Triton. mine came with a fury 3 blade 24 pitch prop. it was real sluggish out of the hole. i went to the 3 blade 23 pitch tempest and It is getting just about the same as yours. I thought about a 4 blade, but wasn't sure if the 115 was enough motor for it.

[PECo]

1 hour ago, Weedwhacker said:

Thats pretty good. i have a ranger z175 I think it is similar to the Triton. mine came with a fury 3 blade 24 pitch prop. it was real sluggish out of the hole. i went to the 3 blade 23 pitch tempest and It is getting just about the same as yours. I thought about a 4 blade, but wasn't sure if the 115 was enough motor for it.

What kind of 115 do you have? 24- and 23-inch pitch props seem like a little much. My three-blade was a 20-inch pitch Mercury Laser II. My Spitfire X7 is only a 19-inch pitch. I did a prop slip calculation, once, and it showed that the Spitfire X7 is close to perfect:

 

[Russ E]

26 minutes ago, PECo said:

What kind of 115 do you have? 24- and 23-inch pitch props seem like a little much. My three-blade was a 20-inch pitch Mercury Laser II. My Spitfire X7 is only a 19-inch pitch. I did a prop slip calculation, once, and it showed that the Spitfire X7 is close to perfect:

 

2017 mercury pro xs 115 with command thrust lower unit. Its geared lower. 2.38-1 and can run the big props.  

Wot was  5500 rpm with 24 pitch.

dropped down to 21 pitch and bumped up to 6300 rpm. maybe higher I hit the limiter.  (Cabelas did not have a 23 pitch at the time)

went up to 23 and now wot is right at 6000  rpm.  with myself and full tank of gas it will run just shy of 50 mph in the summer.  A little over 50 in the spring.

[PECo]

Nice! I have the standard gearcase. I'd been wondering whether the Command Thrust gearcase would have made a difference. I guess that it would.

 

Apologies to the OP for hijacking this thread.

[Russ E]

6 hours ago, PECo said:

Apologies to the OP for hijacking this thread.

same here sorry for deviating.

 

on the topic of 4 blade. when I was trying to get the correct prop for my boat. the shop told me a 4 blade was good for getting on plane with a heavy load and gives better bite in turns, but you could lose a little speed over the 3 blade.

in my case it wasn't necessary . my 3 blade works fine.

 

[3crows]

I have a Boston Whaler Outrage. The Revolution 4 prop replaced a Mirage 3. The four blade provides a lot more lift, planes out quicker, holds the boat on plane at slower speeds and is a wonder in aerated water such as riding the back of a swell through an inlet. I lost probably 3 plus MPH on top but the boat performs better everywhere else. It alos bites and holds better in aggressive turns and running in rough water. 

[Further North]

9 hours ago, 3crows said:

I have a Boston Whaler Outrage.

I love Whalers...

 

...if they only had more storage...there'd be one in my garage.

[gim]

On ‎9‎/‎15‎/‎2017 at 7:28 PM, slonezp said:

Only guys I know running 4 blades are fishing big water rough conditions or pulling skiers/tubes. The 4 blade give you more bite at lower speed under adverse conditions.

 

I was at the Bassmaster Elite AOY weigh in last Friday and you would be surprised how many of them are using a 4 blade prop on their 21 foot fiberglass rig.  I got up close and personal with at least 8-10 rigs and all of them except 1 was using a 4 blade prop.

[Team9nine]

My last bass boat was a Triton TR176 with a 115hp engine. It came stock with a 3 blade stainless, but I also bought a 4 blade stainless as a backup. After running the rig with the 4 blade, the 3 never went back on. It does make a big difference in some setups.

[Jeff H]

I run 4 blades (Trophy Plus) on my Champion 191 Elite.  More lift, better overall performance, better ride on my hull.

46 minutes ago, gimruis said:

 

I was at the Bassmaster Elite AOY weigh in last Friday and you would be surprised how many of them are using a 4 blade prop on their 21 foot fiberglass rig.  I got up close and personal with at least 8-10 rigs and all of them except 1 was using a 4 blade prop.

Wouldn't surprise me a bit, considering how much crap those guys carry.

[3crows]

1 hour ago, Further North said:

I love Whalers...

 

...if they only had more storage...there'd be one in my garage.

Yes, the small ones, like mine, are short on storage because they maximized flotation. It is as solid as a chunk of concrete, but not a lot of storage. 

 

 

 

It is a fun boat for exploring, diving, riding and fooling around and a great near shore (near being relative) saltwater boat and we have caught a lot of fish. But one thing it is not good at in any way and in fact horrible, it is not a bass boat.

[Further North]

5 minutes ago, 3crows said:

Yes, the small ones, like mine, are short on storage because they maximized flotation. It is as solid as a chunk of concrete, but not a lot of storage. 

Still one of my favorite boats...if I didn't have so much "stuff"...