Octura M or X

[785boats]

One thing to remember is that the M series might give you a little extra top end speed however, it could cause cornering handling issues especially in a mono.

Randy. I've never heard that before.
Could you expand on that a bit please? I'm always eager to learn.

[J.W. Pepper]

One thing to remember is that the M series might give you a little extra top end speed however, it could cause cornering handling issues especially in a mono.

Is that caused by the fact that it's been de-tongued??

I got out my prop can and started doing comparisons, I don't have any "M" series props, but a side-by-side comparison of the PB 1.6 x 2.5 (same as Prather S215) & one of Jan's x440 CNC'ed props allowed me to see enough of a diffrence to understand what they mean when they say the prop has been de-tongued (de-eared).

[785boats]

J.W. Pepper.

Is that caused by the fact that it's been de-tongued??

That must be the case but I'm not sure how & what the effects are. We'll have to wait for Randy.

You said in one of your posts that all you wanted was to be pointed in the right direction.
Let me point you here.

http://www.fastelectrics.net/fe_manual.php

If you read each chapter in the manual you will be a long way to understanding the idiosyncrasies of this sport. It's certainly helped me.
Since we're talking props, start with the chapter 'Propeller Effects'.
Cheers.
Paul.

[NativePaul]

Thanks for the link Paul.

I haven't noticed any handling issues with M series props, but all boats are different, sometimes even ones that came out of the same mould. While nearly all my props are de-tongued to some extent, I don't have many actual M series props, as I generally buy X series and cut to my desired shape, but I have noticed that M seem to have thicker blades than X, so if you are just doing basic sharpening not thinning down to the root there is the potential for more prop walk and torque roll, quite a small effect though I would have thought it wouldn't be noticeable. Another possibility is if an M series was either not big enough for the hull and was cavitating coming out of the bends, when it hooks up the sudden onset of thrust, lift, torque and prop walk could bring with it some bad handling traits that would be fixed by a little more blade area from an X, or a bigger M to stop the initial cavitation and keep things smooth.

There could well be something I haven't thought of or experienced maybe something particular to un-stepped monos that I am not very familiar with, I also await Randy's comment as like the other Paul I am always eager to learn.

[Randy Rapedius]

The tongue on the X series are there to assist in getting the hull on plane and the added blade area makes for smoother turning. Some monos need cornering stability. At top speed, the tongues actually hinder speed. This is why people like to remove them. Last year I took a stock x470/3 for a 90 nitro mono and removed the tongues. The boat was ballistic fast in the straights but in the corners it was squirrely. Put the stock prop back on and it cornered like a dream. Not always does removing the tongue improve over all performance. It's a balance. There are no guarantees that removing the tongues or going from an X to a M Octura series prop will help or hinder. Test, test, and test some more.

[mtbenjamin77]

Its a balance. Usually remove slightly more tongue than the m series and it seems to work well for my FE setups

[mtbenjamin77]

Knowing how to work props is a priceless skill. I can usually run only two different props on the same setup and know how to custom cut a prop to maximize performance based on the handling characteristics of the two

[Brushless55]

so are M props not a good choice for Mono hulls?
I was going to try a M445 on my PSpec Mono next time out and now I'm going to put a X445 on it

[Doug Smock]

FWIW, M series props or X series that I have removed the entire tongue on are all I run on FE monos.

[Brushless55]

FWIW, M series props or X series that I have removed the entire tongue on are all I run on FE monos.

ok hold up..
I am trying to wrap my brain around what you guys are saying...
so the M props as they are could even need more tongue removed and they will run great on monos??

[Doug Smock]

Todd,
Do they "need" more tongue removed? It depends on the boat, RPM, etc. Yes they will run great on monos if they are ''great running" monos.

http://www.youtube.com/watch?v=Ahy6nfMKSx0

Like Randy said, test, test, and test some more. There is no silver bullet one cut fits all.
Randy's 90 mono experience is going to differ from your P Limited mono experience. They are apples and oranges. (different hulls different power requirements)

[Brushless55]

Todd,
Do they "need" more tongue removed? It depends on the boat, RPM, etc. Yes they will run great on monos if they are ''great running" monos.

http://www.youtube.com/watch?v=Ahy6nfMKSx0

Like Randy said, test, test, and test some more. There is no silver bullet one cut fits all.
Randy's 90 mono experience is going to differ from your P Limited mono experience. They are apples and oranges. (different hulls different power requirements)

that one in the video looks really good...
turns nice!

[785boats]

Thanks guys.
I run a lot of de-tongued X series & also the M series & haven't noticed any bad behaviour. That's why I was curious. Thanks again for the explanation. No doubt I'll come across the problem one day.

[J.W. Pepper]

Thanks for the link Paul.

I haven't noticed any handling issues with M series props, but all boats are different, sometimes even ones that came out of the same mould. While nearly all my props are de-tongued to some extent, I don't have many actual M series props, as I generally buy X series and cut to my desired shape, but I have noticed that M seem to have thicker blades than X, so if you are just doing basic sharpening not thinning down to the root there is the potential for more prop walk and torque roll, quite a small effect though I would have thought it wouldn't be noticeable. Another possibility is if an M series was either not big enough for the hull and was cavitating coming out of the bends, when it hooks up the sudden onset of thrust, lift, torque and prop walk could bring with it some bad handling traits that would be fixed by a little more blade area from an X, or a bigger M to stop the initial cavitation and keep things smooth.

There could well be something I haven't thought of or experienced maybe something particular to un-stepped monos that I am not very familiar with, I also await Randy's comment as like the other Paul I am always eager to learn.

Thanks for the link Paul... +1

[Accessable]

This is all well and good for monos.
So what's the go for serious outboard FE F1 tunnels?
I currently have a range of Octura X series props ranging from X430 through all variations to X450.
All are balanced and sharpened per me.
I currently have a Thunder Power 6S 8G 70C LiPo setup running thru a Swordfish 300 Pro Plus so power is NOT an issue.
This is delivering to a variety of TP 4060 (1800 - 2100 Kv) brushless on a TFL OB leg.
BTW: From my ski race experience: There is a little thing called the "paddle wheel effect".
This is a semi-surfacing propeller's desire to "walk" sideways" across the water at the same time as pushing the boat forwards. - aka as "chine walking".
I've experienced this problem 1st hand having done a 180 loop at 100+ MPH.
My once dislocated shoulder still aches!
Dual counter-rotating propellers or offsetting the horsepower supply sorts the problem out.
WTF would I know???