3-blade vs. 2-blade trolling motor prop

[albright1695]

Pros and cons of both a 3-blade and a 2-blade trolling motor prop? Specifically on a Motorguide.

 

[fender66]

I like my 2 blade better. I have more thrust and can run my motor at lower speeds because of that. My spare prop is a 3 blade that I thought I'd like better but didn't....and yes, it's Motorguide.

 

[user 6672]

I have a metal 3 blade on my 109# 36 volt Motorguide and it is a work horse and tough as nails. Never used a 2 blade.. i guess my logic was one more blade is better at least with the larger system's.

I like my 2 blade better. I have more thrust and can run my motor at lower speeds because of that. My spare prop is a 3 blade that I thought I'd like better but didn't....and yes, it's Motorguide.

fender.. do you think you get more thrust because it has less blades to turn and it turns faster? I know it isnt to big of a pita to swap out.. you should try to gps the 3 n 2 blade at the exact same setting under same conditions.. id be interested in the outcome..

 

[RiverBottomOutdoors]

I've read that 3 blade props are less likely to cavitate at shollow depths.

I have a 55lb with 3 blade Motorguide Machete prop on my 1448. Chops right through the hydrilla.

 

[fender66]

I have a metal 3 blade on my 109# 36 volt Motorguide and it is a work horse and tough as nails. Never used a 2 blade.. i guess my logic was one more blade is better at least with the larger system's.

I like my 2 blade better. I have more thrust and can run my motor at lower speeds because of that. My spare prop is a 3 blade that I thought I'd like better but didn't....and yes, it's Motorguide.

fender.. do you think you get more thrust because it has less blades to turn and it turns faster? I know it isnt to big of a pita to swap out.. you should try to gps the 3 n 2 blade at the exact same setting under same conditions.. id be interested in the outcome..

I actually did GPS the two. Can't remember the speed difference, but the 2 blade was noticeably faster. Reason is that the 2 blade has bigger/wider blades and probably have more pitch to them.

 

[FuzzyGrub]

I have both 2 and 3 blade plastic props for a 45lb MG Wireless. From memory, on high, the gps speed diff was about 0.2mph on my boat. I use the 3 blade weedless only on waters where it will be needed. Weedless actually means less weeds than 2 blade.

FWIW: the 3 blade is a latter version of MG machette that has the a taper to the hub, post blades. Older version had a straight hub.

 

[albright1695]

Good info fellas and thanks for all of it. I have a 3 blade now but its looking a little rough . So I think I will try a 2 blade. I had a 2 blade on my old boat(minnkota) and I agree I think it was a touch faster. Weeds arent a big problem on most lakes I fish so a 2 blade may be my best choice.

Im gonna clean up the 3 blade with a little sandpaper and keep it as a backup or for weedy lakes.

 

[CodyPomeroy]

I asked the same question to a motor tech. regarding my outboard and he said it depends on the pitch of the blades.

 

[FuzzyGrub]

I asked the same question to a motor tech. regarding my outboard and he said it depends on the pitch of the blades.

That is true for gas motors. Trolling motor props don't come in multiple pitches. They are all an extremely low pitch. I believe the pitch of these props is about or is the same. Also think total blade area is close. I'll try to check tonight.

 

[user 6672]

I actually did GPS the two. Can't remember the speed difference, but the 2 blade was noticeably faster. Reason is that the 2 blade has bigger/wider blades and probably have more pitch to them.

thats odd.. for the same amount of rpm with either 3 or 2 blades you'd think that the 3 would pull harder.. more surface area doing the same amount of rpm..

 

[fender66]

I actually did GPS the two. Can't remember the speed difference, but the 2 blade was noticeably faster. Reason is that the 2 blade has bigger/wider blades and probably have more pitch to them.

thats odd.. for the same amount of rpm with either 3 or 2 blades you'd think that the 3 would pull harder.. more surface area doing the same amount of rpm..

It's actually not the same amount of surface area. The blades on the 3 prop are smaller than on the 2 prop.

 

[user 6672]

So the 3 smaller don't have the same or more surface as the 2 larger?

the 2 must be huge..

Hmmm... wish i was good at math n stuff..

 

[fender66]

So the 3 smaller don't have the same or more surface as the 2 larger?

the 2 must be huge..

Hmmm... wish i was good at math n stuff..

There is a definite difference in prop surface area if you compare 1 blade from each. Surface area total between both props (complete), may be pretty close... Still, my 2 blade is faster than my 3 so there is a difference.

 

[user 6672]

There is a definite difference in prop surface area if you compare 1 blade from each. Surface area total between both props (complete), may be pretty close... Still, my 2 blade is faster than my 3 so there is a difference.

Not arguing you that there is a difference.. at all. Just surprised i guess.

 

[fender66]

There is a definite difference in prop surface area if you compare 1 blade from each. Surface area total between both props (complete), may be pretty close... Still, my 2 blade is faster than my 3 so there is a difference.

Not arguing you that there is a difference.. at all. Just surprised i guess.

I never even read an argument.....I wish I had a better answer too. I can say that I noticed it enough that I only used the 3 blade prop once and immediately changed it back to my 2 blade. One use...that's all it took. Still....I wish I had a better answer.

 

[FuzzyGrub]

Yes, I said the TOTAL blade area, I think, is about the same. A single blade of the 3 blade is much less compared to a single from the 2 blade. From memory, the outer diameter (blade tips) of the 3 blade is less than the two blade, as well.

I'll put them side by side this evening and report back.

 

[user 6672]

Even on MG's site shows the props.. the blades actually look smaller on a 2..

https://www.motorguide.com/store/accessories/propellers

Maybe an optical illusion.. jeesh i gotta eat.. all coffee and no food make me summtin summtin summtin..

 

[FuzzyGrub]

From a prop to prop comparison: (Machette III vs Powerprop)

- Each single blade on the Powerprop has less area than each on the Machette III
- So Machette III wins for total surface area, hands down
- Powerprop has about 1" larger overall diameter (1/2" per blade) Measured shaft to tip
- Pitch looks the same or the Machette III has slightly more. Because of the taper on the back of the hub, it is hard to compare.
- Curvature of blades looks very similiar

So what's it mean? Not much. I'd still go by the gps data. The Powerprop will be slightly faster than Machette III.


Now, I have another older 3 blade prop. It is a MG Competition Series Hannon Systems. It looks similiar to Machette I and II.

- Each blade is smaller than than each blade on the power prop (surface area)
- Total surface area of these 3 blades is still more than 2 blade powerprop
- Outer diameter is same as Machette III
- Pitch looks the same as Powerprop and Machette
- I don't have gps on this one


Note: These are all 3 1/2" hub size props