Propeller cup on leading edge?

[native2]

I have heard of people adding cup to leading edge of the prop blade. I know cup on trailing edge adds bow lift ect. But what does cup added to leading edge do? Friend of mine says it helps reduce slip. Does it also add bow lift? Does it change the pitch much? Any thoughts from the prop gurus?

[olboatman]

I am not a prop guru that said I have also read that it reduces slip and if I remember correctly better for "bite" in corners. Guys please correct me if I am incorrect. Gary

[Mr. Demeanor]

What your talking about is progression. Its done to help holeshot but usually hurts top end. Common on drag style props. It holds the water on the blade instead of it rolling off and reduces overall pitch.
Its not really cup in the sense of cup at the trailing edge.

[lance]

I've heard it referred to as rolling the leading edge of the blades. It is done to increase hole shot.

[frederick55]

In the 80's it was called triple cupping. Prop technology wasn't what it is now, and it helped reduce slip on holeshot and throughout the rpm range. Saw my best numbers back then with a prop worked that way. Actually seemed to add pitch.

[XstreamVking]

Some of the extreme shallow water tunnel boats run the rolled edge props for more efficient slip #'s in the disturbed water coming off the hull. Think of it like a scoop on the props leading edge.

[Motv18]

Iirc theirs also a reverse thrust cup. Semi rare these days. Way back some of the go fast prop wouldn't even back you off the trailer.

[pyro]

What Lance said... Leading edge "roll." It is said to reduce slip coming on plane.

[Magcat 62]

I can tell you eirst hand about leading edge cup because i have a dennis over hub from 1987 days go fast bass boats, it the hottest prop i ever owned i run it on a 1962 magcat talk about hole shot! run manual jack plate real high Stands boat straight up and im gone, does add about 1' PITCH I TEsted it against 24 chopper 24 cleaver NO comparison, when i first looked at it i thought some one ran it in sand all day because of the weird blades it looks like a chopper but its not a merc prop never any thing like it it was mfg in central fla, I think it was for drag racing plus has great top end All i need is hyd, steering If you ever see DENNIS stamped on hub try to buy IT I lucked out for once art

[Magcat 62]

prop technology isnt what it is now? i really have to think about that. ill put that 1987 DENNIS up against anything on the market today. see my thread. art

[Magcat 62]

great bow lift I run a 23 cupped leading edge DENNIS 1987 over hub. rare bird art

[olboatman]

great bow lift I run a 23 cupped leading edge DENNIS 1987 over hub. rare bird art

Art Is there any way you could post a pic of that Dennis prop? Would like to try to have a prop I like have the leading edge cupped if I could show the shop what it should look like. If you can't maybe you could explain where the cup starts and stops. Thanks Gary

[frederick55]

prop technology isnt what it is now? i really have to think about that. ill put that 1987 DENNIS up against anything on the market today. see my thread. art

What I should have said was, " the thinking on prop technology wasn't what it is now". I had a Pendergrass 28p overhub Hooter prop in the early 80's. I had Frank & Jimmie's Propeller roll the leading edge. We called it triple cupping. Was the best prop I had. On an 18' Action with a 200 X-Flow, I could outrun all the Merc guys running Choppers with same boat/setup. The prop sounds similar to what you had. Loved it. If I ask about triple cupping now, I get looked at like I've got three heads.

[texasvector]

i bought a 28 hoss triton that has this "roll" ....quite drastic really.....it does hook up coming outta hole ...alot better than my 28 et..but on my rig its a handful to control up top....wild as F......et much easier to drive

[Motv18]

yep a steep progressive pitch, say 5-27 instead of a flatter 11-27 they definitely spool up faster for holeshots. also bite a little better running half out but to much and you hole the water for the next blade (increase slip).

tried a 3-30 on a drag once and had to back off hooked like crazy hell but was to much water impact at speed the hydrodynamics had to much flowing out the radius, and any correcting to that slowed it down to much.