ProBoat prop sizing confusion

[Hawcer]

Ok, I’m confused. The prop on my UL-19 is listed as a 1.7x1.6

From what I can tell with most other prop manufacturers , the first number is the pitch and the second is the diameter.

ProBoat seems the other way around. My prop diameter measures out at 1.7”, so I’m guessing the pitch is 1.6”. Opposite of what I thought to be true.

So, does this mean the optional prop (PRB282028)recommended by ProBoat to use (1.4”x1.65”) has a diameter of only 1.4”? Seems a bit small.

Anyway, due to my confusion, I ordered a x442 (1.4x1.65). It has the expected 1.65” diameter. It also works great.

[dasboata]

no first # is diameter and the 2nd # is pitch ratio so 1.7X1.6=2.72" of pitch theoretically

[Hawcer]

no first # is diameter and the 2nd # is pitch ratio so 1.7X1.6=2.72" of pitch theoretically

For ProBoat or all props?
Why does octura list them like this then.
Example:
X642 - 1.6x1.65. 1.6 being the pitch?x 1.65(42mm) being the diameter?

I was reading their numbers as (X6) x 1.65” , or 1.6 ratio x 1.65 diameter. So I assumed proboats 1.7 x 1.6 was pitch ratio x diameter.

I’m still confused on this unless ProBoat is reversed.

And to be clear.
The ProBoat 1.4x1.65 is a 1.4” diameter prop with a 1.65 pitch ratio?

[Speed3]

The first part is diameter rated by inches, and the second represent pitch ratio.

So what about 1919 10 rake, 55 blade ratio, 2blade.

Different manufacturers list dimensions differently.

[dasboata]

For ProBoat or all props?
Why does octura list them like this then.
Example:
X642 - 1.6x1.65. 1.6 being the pitch?x 1.65(42mm) being the diameter?

I was reading their numbers as (X6) x 1.65” , or 1.6 ratio x 1.65 diameter. So I assumed proboats 1.7 x 1.6 was pitch ratio x diameter.

I’m still confused on this unless ProBoat is reversed.

And to be clear.
The ProBoat 1.4x1.65 is a 1.4” diameter prop with a 1.65 pitch ratio?

with octura example 642 42mm and 1.6 pitch ratio 442 42 mm,,1.4 pitch ratio

[dasboata]

The first part is diameter rated by inches, and the second represent pitch ratio.

So what about 1919 10 rake, 55 blade ratio, 2blade.

Different manufacturers list dimensions differently.

go away !!! don't confuse the guy anymore your numbers are not even close and your explanation is wrong

[Hawcer]

So.......pretty much ignore all ProBoat props. And follow/use the given specs that each manufacture uses on each specific prop.
Octura I understand.
ABC props I’m guessing like a 1716 would be 1.7 diameter x 1.6 ratio.
I’m lost on Prather, but will prolly never use one.
Others like cnc is self explaining by size

[dasboata]

So.......pretty much ignore all ProBoat props. And follow/use the given specs that each manufacture uses on each specific prop.
Octura I understand.
ABC props I’m guessing like a 1716 would be 1.7 diameter x 1.6 ratio.
I’m lost on Prather, but will prolly never use one.
Others like cnc is self explaining by size

yes on the ABC props Prathers have there own numbering,,, you need a prather chart, pro boat uses the same as ABC I am assuming,,,, but none are ever accurate so it's just used as a reference

[David Brock]

My question kind of ties into this as I just picked up a Ul-19 Monday and inherited an AQ Motley Crew. I have a new motor on order for the AQ MC since the one in it doesn't fall in the rules. (Went with the same motor as in the UL-19). So I'm going to have to get familiar with props. How do you know where to start your prop testing at? How does Prop diameter affect a boat (Larger vs smaller)? Same thing for Pitch, how does a props pitch affect the boat (more vs less)? How do the diameter and pitch work together or against each other?

[gearhd48]

Maybe study this and it can help. https://forums.offshoreelectrics.com/album.php?albumid=991

[Hawcer]

My question kind of ties into this as I just picked up a Ul-19 Monday and inherited an AQ Motley Crew. I have a new motor on order for the AQ MC since the one in it doesn't fall in the rules. (Went with the same motor as in the UL-19). So I'm going to have to get familiar with props. How do you know where to start your prop testing at? How does Prop diameter affect a boat (Larger vs smaller)? Same thing for Pitch, how does a props pitch affect the boat (more vs less)? How do the diameter and pitch work together or against each other?

I’m new to this too, and it seems to be a bit of a dark art. I kinda relate it to what I know.
Like engines...

I treat voltage like cubic inch, motor kv like a camshaft and the prop like the gear ratio....and then apply some common sense.

Anyway, some things I’ve noticed in the very short time I’ve had a boat.

- smaller prop diameter or pitch = less load on the motor which raises rpm and reduces temps...but can sacrifice speed. But You may also see speed increases if the prior prop was really inefficient for the volts, kv of the motor, or size of the boat.

De-tongued props seem better suited for wide open throttle. Reduces load at speed, but are slower and slip a bit more out of the whole on acceleration.

The stock UL-19 appears to be de-tongued.

I started testing at 42mm. 1.4 pitch and 1.5 pitch. Stock is 1.7” x 1.6 pitch, that’s pretty big for 4s 2000kv imo.