Prop recommendations - Different pitches & diameters, plus 2-blade vs 3-blade

[Panther6834]

I'm not entirely certain of the best way to word my questions...or even how, specifically to ask them, so pardon if this seems like a "jumbled mess". Adding confusion to the c chaos, this isn't related to any one specific boat - these questions could be applied equally to a monohull, a cat, a hydro, or outrigger. In my case, right now, this relates to three different boat of two different types (mono & cat), and two different motor/prop configurations (single & twin). Anyway, here goes nothing.....

To start, I'm going to ignore the 2- vs 3-blade part of this mess, as that would probably mess with people's minds too much...as I've been known to say, "Start easy, then go hard." Assume the same motor, ESC, and battery for all possibilities, and assume that the motor & ESC are more than capable for all possibilities. In regards to diameter & pitch, I'm going to first toss out a couple of 'pairings':

1715 vs 1814
1716 vs 1815
1716 vs 1814

For these pairings, think of them as all 2-blade and/or all 3-blade combos. Just looking at these combos, in terms of speed, stability, and any other points you might think of, what might be the advantages/disadvantages of each over it's "paired partner"? Also, how would power draw, and ESC & motor temps, be affected? For each pairing, which prop would you prefer, and why? If there's any noticable difference, of each pairing, which would be better for racing (where speed AND controllability matter), which for just 'having fun' (where stability is more important than speed), and which would be better for all-out speed runs?

Taking things up (or down, depending on how you look at it) a notch...now we get into the 2-blade vs 3-blade...here's a few more parings to consider:

1716 2-blade vs 1715 3-blade
1815 2-blade vs 1814 3-blade
1815 2-blade vs 1715 3-blade

For these pairings, the same questions apply. I'm still in the somewhat early in the learning stages of FE, but I think these questions, and the answers to them, could help veterans & newbs, alike.

Yes, I could have selected any number of props...but, in my attempt to keep this as incomplete as possible, I chose to limit the props to just these four diameters/pitches. As readers gain more understanding of the interaction between just these four, we should all be able to apply what's learned to other diameter/pitch combos.

Let the games...and gain in prop knowledge...begin.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[jingalls007]

Dig around in the forums to find the answers you're looking for

[eXoNerated]

Hi Panther,
In short you can start here. A smaller prop at the same pitch will have the potential to be faster as there is less drag. The convo if engaged fully will go all over the place. Its ALOT to talk about. It also WILL have to depend on the boat as far as thrust cones etc are considered. Some larger lower piched prop just do better on some boats. The other thing to considers is the load it puts on the motors. Lohring looked and determined increase in load was more a proponent of diameter vs pitch. That's another angle to consider. Then you have the rake and what it does with the bow of the boat. Raise it or lower it. This is one of those 20,000 view threads. Ill likely bow out before it begins really coz the debates will go on forever. I have the newest works on supercavitating propeller profiles and Its a great source of information about SP props.I think Ill share just that and run for the hills.... If you want everything I got which is alot Pm me.


Regards
Hubert,

[1coopgt]

I'm not entirely certain of the best way to word my questions...or even how, specifically to ask them, so pardon if this seems like a "jumbled mess". Adding confusion to the c chaos, this isn't related to any one specific boat - these questions could be applied equally to a monohull, a cat, a hydro, or outrigger. In my case, right now, this relates to three different boat of two different types (mono & cat), and two different motor/prop configurations (single & twin). Anyway, here goes nothing.....

To start, I'm going to ignore the 2- vs 3-blade part of this mess, as that would probably mess with people's minds too much...as I've been known to say, "Start easy, then go hard." Assume the same motor, ESC, and battery for all possibilities, and assume that the motor & ESC are more than capable for all possibilities. In regards to diameter & pitch, I'm going to first toss out a couple of 'pairings':

1715 vs 1814
1716 vs 1815
1716 vs 1814

For these pairings, think of them as all 2-blade and/or all 3-blade combos. Just looking at these combos, in terms of speed, stability, and any other points you might think of, what might be the advantages/disadvantages of each over it's "paired partner"? Also, how would power draw, and ESC & motor temps, be affected? For each pairing, which prop would you prefer, and why? If there's any noticable difference, of each pairing, which would be better for racing (where speed AND controllability matter), which for just 'having fun' (where stability is more important than speed), and which would be better for all-out speed runs?

Taking things up (or down, depending on how you look at it) a notch...now we get into the 2-blade vs 3-blade...here's a few more parings to consider:

1716 2-blade vs 1715 3-blade
1815 2-blade vs 1814 3-blade
1815 2-blade vs 1715 3-blade

For these pairings, the same questions apply. I'm still in the somewhat early in the learning stages of FE, but I think these questions, and the answers to them, could help veterans & newbs, alike.

Yes, I could have selected any number of props...but, in my attempt to keep this as incomplete as possible, I chose to limit the props to just these four diameters/pitches. As readers gain more understanding of the interaction between just these four, we should all be able to apply what's learned to other diameter/pitch combos.

Let the games...and gain in prop knowledge...begin.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

I consider myself a noob. What is the question you are asking in this wall of words? Stop beating around the bush and just get to the point. I run 1716 props on my Zelos twin 36 . But for the life of me I can't tell where you are going with this thread.

And as a noob I'm pretty sure hull design does factor in on prop choice depending on motor size and battery size choice. Some where on this forum there is a post all about Props and prop design. Maybe you should try and find it . Honestly It was more info than I'm interested in. I don't intend to design props . I would rather leave that to the pros. I can give them my specs and then I can work with them on tweaking the props to dial them in to what I'm looking for and want my boats to do. Good luck

I know I'm coming across as rude or hostile but it's because I don't understand the point of this thread. Sorry

[eXoNerated]

Come on now he can inquire if he has a deeper interest. That's not against any rules and the other thread may not encompass his inquiry. Its totally all right. Don't get upset about it. Not at all trying to be offensive but if you are a self proclaimed newb why not sit back and see if there's something useful for you here? If you are not interested certainly he can still be. Right? Obviously there's alot of things I don't understand about peoples behavior on public forums but this thread certainly isnt one of them. Ironically your post is what I don't understand. Sometimes I think we forget we're in free society.....supposed to be anyway. It could be the fact that you haven't come into the fold that you dont understand what he's after. I admit he wont find it on the pages, it will be on the water, but it's a good topic to get a healthy discussion going about an aspect of boating many of us do have interest in. Why should a forum be dominated and controlled by people who know the least? That also makes zero sense. And again I only use your self proclamation to judge you u could be an expert for all I know. No slight intended. If all we did is refer back to old threads then we may as well archive the forum and leave. Every topic that will be discussed into the future has already been discussed in the past, but realize new developments in the understanding of propellers continues to fall from academia and empirical measure, so please don't stand in the way of technology and people's understanding of it. America has got enuf idiots already that don't know anything. That's why we losing AT THE TRAPS TOO! Whats wrong with you guys? Y'all dont like talking about rc boats?You just like looking at them and running them and give a rats you know what how they work? That's what I don't get. How did the prop experts become that? What happens when the current ones are gone? Do young people realize they should gravitate to knowledge vs excess. Buying a bunch of hulls that don't run worth squat. you supposed to take these torches and run 300 mph by 2050 and beyond. Most of us will be gone. Wake up people. Have an interest in learning. IT'S FUN!

Regards
Hubert

[Panther6834]

Hi Panther,
In short you can start here. A smaller prop at the same pitch will have the potential to be faster as there is less drag.

The other thing to considers is the load it puts on the motors. Lohring looked and determined increase in load was more a proponent of diameter vs pitch. That's another angle to consider.

First. I'm not getting what you said first. If you have two props of the same pitch, and different diameters, how can the smaller diameter be faster? Doesn't the larger diameter prop push more water? Wouldn't that mean the larger diameter should be faster? Obviously, in this, I'm not referring to some "huge diameter difference". If you look at the diameter/pitch combinations I mentioned in my 'samples', you'll notice that they only vary by 1-2mm. If the difference were huge...say...32mm & 40mm, I would understand the "drag" you mentioned, thus the 32mm could easily be faster (on the same boat). But, if dealing with...say...32mm & 34mm, the drag increase should be very minimal, thus we'd be back to the fact that the 34mm prop pushes more water than the 32mm...right?

As for the "load", that's actually pay off why I brought the topic up, and why I decided to only list a few combinations. The diameter/pitch variations within each pairing are minimal enough that I was curious how speed, as well as motor-load would be affected. Also...I'm not starting the pairings as if they were on two different (say, V vs cat) boats - for each pairing, assume that both props would be installed on the same boat, no matter what that boat might be.

I didn't create the thread to specifically help me...I created it for all. People, myself included, are always interested in knowing how a 'change' will affect things like speed, handling, and motor-load. For newbs, this is even more important. I created the thread so that those "in the know" could present the info in simpler-to-understand ways, so that all...newbs, and "salty dogs", alike, might gain knowledge. As you said, yourself, the industry is constantly changing, and even those who know a lot (in regards to 'old' technology) still learn...especially when it comes to 'new' technology.

Every "pairing" will affect a boat differently. Using just one combo ..say, 1715 vs 1814...as an example, these two will, obviously, have different effects...but, my 'query' was more about "how". For example, just using these two props, would one be faster (and which), would one create better handling (and which), and would one put a greater load on the motor (and, once again, which)? In this, it's not really about the "boat", but about the 'differences' between the props in any pairing.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[eXoNerated]

If speed is pitch times rpm but one has less drag why wouldn't it be faster?just think about it for a minute. They have the same pitch. Thrust is a proponent of slip not speed. Ie a tug boat has more thrust than a speed boat and alot of slip but it isnt fast . Typically SAW fe is smaller diameter large pitch props. There is no way here to tell u exactly wat will happen there are too many variables. At least for me. When I comes to props empiracle evidence reigns Supreme. Even the temp of the water makes a difference. Typically the larger blade area wiil the higher the load at the same rpm. Faster would be faster by a 10 mph difference or a half mile an hour one. That should be enuf to point to minute differences in drag . The other thing to consider is the AR. Or aspect ratio. That's the XX14 ...XX15 you see at the end of the ABC's Typically higher AR generates more lift so now you have to consider the hull and whats appropriate for its running attitude. From this its probable the 1.5 AR has more lift than the 1.4 but it would be minute if the leaf is basically shaped the same.

Regards
Hubert

[HTVboats]

The simple NOOBY answer in my experience (40+ years) is understand what you are working with. I find it easiest to figure out each prop diameter and pitch in millimeters. Octura's are easy. X450 or 1450 different blade designs but 50mm diameter times 1.4 pitch ratio. 50X1.4=70mm pitch. ABC uses inches and pitch ratio 1814 is 1.8" X 1.4 pitch ratio - 1.8 X25.4 = 45.72mm so to simplify round up 46 X 1.4 = 6.4.4 (65)mm 1914-48X1,4=67mm 1915 -48X1.5=72mm. Simple calculator(on your phone). This is just basic. Then comes the fun, blade area, blade rake, blade style, progressive pitch, trailing edge cup?
Now realize every hull needs X amount of blade area to push or thrust the boat to an efficient speed. Bow lift, tail lift, angle and height of strut come into play. For a noob either buy and try different props and do adjustments or have your favorite prop guy recommend and cut props for you. Trial and error will increase your knowledge.
As for 2 or 3 blade I like 3 when possible but bear in mind 3 blades have more area to push and have 50% more cutting edge drag. That said in general less diameter and pitch going to 3 vs 2 blades. A 3 blade has less tendency to be a paddle on a surface drive.
Try all the props you have and can borrow within pitch ranges you find that work on your hull. Be careful going too far up in diameter as load increases more than with pitch.
Mic

[Panther6834]

Thanks, Mic. Now, that's a reply that makes a bit more sense, and one that people...newbs & old timers...can understand.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[1coopgt]

Come on now he can inquire if he has a deeper interest. That's not against any rules and the other thread may not encompass his inquiry. Its totally all right. Don't get upset about it. Not at all trying to be offensive but if you are a self proclaimed newb why not sit back and see if there's something useful for you here? If you are not interested certainly he can still be. Right? Obviously there's alot of things I don't understand about peoples behavior on public forums but this thread certainly isnt one of them. Ironically your post is what I don't understand. Sometimes I think we forget we're in free society.....supposed to be anyway. It could be the fact that you haven't come into the fold that you dont understand what he's after. I admit he wont find it on the pages, it will be on the water, but it's a good topic to get a healthy discussion going about an aspect of boating many of us do have interest in. Why should a forum be dominated and controlled by people who know the least? That also makes zero sense. And again I only use your self proclamation to judge you u could be an expert for all I know. No slight intended. If all we did is refer back to old threads then we may as well archive the forum and leave. Every topic that will be discussed into the future has already been discussed in the past, but realize new developments in the understanding of propellers continues to fall from academia and empirical measure, so please don't stand in the way of technology and people's understanding of it. America has got enuf idiots already that don't know anything. That's why we losing AT THE TRAPS TOO! Whats wrong with you guys? Y'all dont like talking about rc boats?You just like looking at them and running them and give a rats you know what how they work? That's what I don't get. How did the prop experts become that? What happens when the current ones are gone? Do young people realize they should gravitate to knowledge vs excess. Buying a bunch of hulls that don't run worth squat. you supposed to take these torches and run 300 mph by 2050 and beyond. Most of us will be gone. Wake up people. Have an interest in learning. IT'S FUN!

Regards
Hubert

Generally when I want to learn something I ask a direct question. From there I'll ask others if something doesn't make since to me. I'm an Manufacturing Engineer so that's my excuse plus I had had a couple beers last night and just found the post frustrating . Carry on.

[Panther6834]

Generally when I want to learn something I ask a direct question. From there I'll ask others if something doesn't make since to me. I'm an Manufacturing Engineer so that's my excuse plus I had had a couple beers last night and just found the post frustrating . Carry on.

Glad to hear you're a "manufacturing engineer", and not an English teacher, as there's no excuse for poor spelling and/or grammar.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[eXoNerated]

Let me break the ice and stay on topic while I still remain. Could one of the "experts" tell the forum what we are looking at here? Let me see where you at about a prop.

[HTVboats]

Wow it sure looks like "empiracle evidence" to me.

[eXoNerated]

Does it look like that's what "it " is 1coopgt ? I can assure you Jim S (ABC) the makers of these props they are discussing does. Send the attachment to him to get an answer.

See.....let it go. Let the discussion run it's course because maritime engineers know that most everything about a prop isn't learned in competition setting. Perfection of propeller design require incredible math! There's no way these calculation would be done anytime soon without discrete analytic tools that are verified through models and "empirical" comparison. Academia always does that that's scientific process. Engineers are familiar with the practices I don't have to explain this to you. They never use one data set to make conclusions from. Those are the notions of those not involved at this level. Simple as that. Firstly you still haven't been told what it is yet. If you are truly at a prop you should at least have a clue. Trial an error is great and useful but it isn't exacting enough to consider it a broad knowledge status of "prop expert". To me it means exactly what it is I found the good prop for my boat by trying everything BUT I still don't know why it ended up being the best prop. That answer cannot be found the water so there's a dilemma here for anyone that thinks that. Enjoying the thread carry on. AND REMEMBER JUST LIKE YOU SEE IN YOUR QUOTE "NONE OF IT WILL BE FOUND ON THESE PAGES"

Some of us haven't fully read all the post b4 making cute comments

But its all good. I told you so.... what good would a true guru be if his information is totally incomprehensible by a newb? they don't speak the language of old timers who know anyway. Let him have what he wants. The obvious.... Ask for information then slam the deliverer of it. That's wonderful I said things that didn't make sense but it's valid.

The empirical is what panthers is after but "empiracle" doesn't pass his grammar test. I'm certainly no grammar teacher but most time I can spell or notice the red line beneath. LOL

Reading with great interest. I agree with you now. If he wanted a "specific" answer merely to concur with his own thinking it isn't an honest thread. He shoulda asked. I agree.

Regards
Hubert

[1coopgt]

Does it look like that's what "it " is 1coopgt ?


Hubert

You're asking the wrong person. I've no clue and apparently I've offended an English teacher. Carry on