Reducing TE cup on 19deg-38bar abc

[Rod Fonda]

Here’s some pics of what I use. FYI, my hands have have surgeries and I know Mark and others use different tools but this works for me. These are the adjustable wrenches I use and the anvil I use to work props.View attachment 291004View attachment 291004

Nice one John,,I see what you mean about the graduation marks on the cresents,to know how much of the edge you're bending and do the same on the other blade,,so you bend first,then smooth out on the anvil ?,,so you can basically add pitch to any prop or one you took too much out of by grinding the edge pitch,,Ive also noticed some guys removing the tongue and lead edge on these high rake .38 bar props,almost like a tether boat prop,but I suppose it gives them too much lift and only good for SAW,,Thanks for sharing your secrets,I'm getting inspired haha,,cheers

 

[John Beardslee]

You weren’t John. At first glance it seemed the flapper wheel was much bigger then the actual dimensions. Nothing you did.

Oh, that pic is of an 1815 prop, yea it looks huge.

 

[John Beardslee]

Mark check the blade after the 5 deg boost pitch on the 38 bar 21 and 22 diameter props and tell me what you find.
Then check just the 5 deg before the trailing edge and calculate the pitch ratio and tell me what you find?

David it’s not uncommon to have pitch progression from for to aft as well as from the hub out to the tip.
Thanks John

 

[dwilfong]

David it’s not uncommon to have pitch progression from for to aft as well as from the hub out to the tip.
Thanks John

The blades are all the same just boost pitch changes to get the pitch ratio of 1.5 1.7 and 1.9 even with different diameters. Same blade just different diameter and different boost pitch.

 

[Kris Flynn]

the biggest thing you will find with the newer style ABC props is that a small mount of 'cup' added with pliers = ALOT compared to an Octura.

IE it is VERY easy to over do the cupping of the newer props, a LITTLE goes A LONG way (as far as load on the motor goes)

 

[Rod Fonda]

the biggest thing you will find with the newer style ABC props is that a small mount of 'cup' added with pliers = ALOT compared to an Octura.

IE it is VERY easy to over do the cupping of the newer props, a LITTLE goes A LONG way (as far as load on the motor goes)

Thanks for the tip Kris, I suppose its looking at a way to restore these props if one grinds out too much TE cup,,oops lol ,,Ive also noticed you guys are cutting down blade area and reshaping the LE on these props for SAW,,Do you's do the same for heat racing or do they have too much lift or don't work right ?,,cheers

 

[Kris Flynn]

for oval racing, the awesome part about these newer props is that there are soo many options available, so modifying them is not necessary. Although you do tend to end up with a lot of props (these are VERY easy the sharpen and balance yourself).

There is no doubt these props are faster in a straight line than older generation props (in my experience), but as for oval racing, the jury is still out as to whether they are faster or not. I still like the way the older ABC and Octura props hold my boats (Mainly outboard tunnels) and steer in oval trim.

 

[John Beardslee]

the biggest thing you will find with the newer style ABC props is that a small mount of 'cup' added with pliers = ALOT compared to an Octura.

IE it is VERY easy to over do the cupping of the newer props, a LITTLE goes A LONG way (as far as load on the motor goes)

Kris, It could be that with the higher rake props the cup is more efficient because the water flow stays on the blade better and not thrown out off the blade.
Thanks John

 

[John Beardslee]

for oval racing, the awesome part about these newer props is that there are soo many options available, so modifying them is not necessary. Although you do tend to end up with a lot of props (these are VERY easy the sharpen and balance yourself).

There is no doubt these props are faster in a straight line than older generation props (in my experience), but as for oval racing, the jury is still out as to whether they are faster or not. I still like the way the older ABC and Octura props hold my boats (Mainly outboard tunnels) and steer in oval trim.

Kris, for years in full size outboards the theory was that you needed an elephant ear style propeller to carry or lift the weight of the engine. They’ve found other design options and multi blade wheels that are an improvement.
Thanks John

 

[Timbo Whalen]

Is it best to just backcut TE,,or blend it down along the TE cup face to reduce some cup on a 2217- 19deg-38 abc ?,,would it be better to reduce more closer to hub and leave more at the tips ?,,,cheers

Start by measuring it real good and leave 10%-15% of TE cup in place, to start.

 

[Timbo Whalen]

Kris, It could be that with the higher rake props the cup is more efficient because the water flow stays on the blade better and not thrown out off the blade.
Thanks John

Also wondering if there's some structural intent there, too, for the FE guys....
just a rumor I heard.

 

[Rod Fonda]

Start by measuring it real good and leave 10%-15% of TE cup in place, to start.

Thanks Tim,,I will do a little at a time and test,,cheers

 

[Rod Fonda]

Also wondering if there's some structural intent there, too, for the FE guys....
just a rumor I heard.

The blades do look quite thick around the TE,,Do you's run as is, just s/b, or do you's thin the blades out ?
They look more like brass/bronze than be/ copper and look stronger

 

[Kris Flynn]

Also wondering if there's some structural intent there, too, for the FE guys....
just a rumor I heard.

Please elaborate more
i dont get what you mean thats all?

The blades do look quite thick around the TE,,Do you's run as is, just s/b, or do you's thin the blades out ?
They look more like brass/bronze than be/ copper and look stronger

Personally, I dont focus on thinning the blades on these newer props, i focus on sharpening and balancing, which does thin them naturally, but I dont focus on it. Some will tell you that you have to, but IMHO, not unless you are chasing that last "last few %" out of the prop. Cutting/shaping/grinding out cup are all far more promising areas to find gains.

 

[Rod Fonda]

Please elaborate more
i dont get what you mean thats all?


Personally, I dont focus on thinning the blades on these newer props, i focus on sharpening and balancing, which does thin them naturally, but I dont focus on it. Some will tell you that you have to, but IMHO, not unless you are chasing that last "last few %" out of the prop. Cutting/shaping/grinding out cup are all far more promising areas to find gains.

Thanks Kris,,just what I wanted to hear lol,,I don't want to go mad thinning the blades,, too much work and dust,,so you only reshape/cut down the LE for saw and leave them alone for oval basically?

 

[Kris Flynn]

Thanks Kris,,just what I wanted to hear lol,,I don't want to go mad thinning the blades,, too much work and dust,,so you only reshape/cut down the LE for saw and leave them alone for oval basically?

I have not played with leading edges as such. I have reduced diameter, ground out "cup" in the trailing edge, back cut or barr cut and cupped them a bit to suit each application...but "stock" shape works very well.

Just stick to sharpen and balanced for now on a few (new style ABC that is), then tweak to suit what you want from it as the boat requires.

 

[Rod Fonda]

I have not played with leading edges as such. I have reduced diameter, ground out "cup" in the trailing edge, back cut or barr cut and cupped them a bit to suit each application...but "stock" shape works very well.

Just stick to sharpen and balanced for now on a few (new style ABC that is), then tweak to suit what you want from it as the boat requires.

I was curious about the cut down/reshaped LE after seeing one of Aaron's new style props looking like an aeroplane prop lol,,,I assume it would end up with more LE pitch / lift and some slip to launch big pitch props for SAW,,I also noticed an old post from Mark Sholund suggesting a slight bend to increase LE pitch on a stock new style prop,,So the old tricks like back cut and barr cut still apply and shouldn't weaken them too much as they look quite meaty around the hub area

I was able to purchase a 2117 from Walt,so hopefully it will be good to go with just a sharpen and b,and keep the 2217 for higher nitro and experimenting,,cheers Kris

 

[Mike Cathey]

Here's a photo of my boat using the 2315/19/38. Using the same strut depth/angle as a 260 it was insanely aired out. I had to drop the strut a 1/4" to start getting it settled down. It was amazing the boat got through 3-4 laps of race water before it dumped with only the tips of the prop, turn fin and rudder in the water but boy was she hauling the mail up to that point.