ABC Prop Rake

[Vinbul]

Hi guys, as a friend of mine offered me to cut some props for me I want to order a complete series of ABC Props.
I have already some Prather Props with pitch 1,5-1,6 and that’s why I decided to take ABCs with a 1,4 pitch.
Probably 1614 - 2214...
As I see I can order the ABC Props with a different rake. 10 or 17.
What would be the better choice for boats like Monos 80-100cm and Cats/F1 80-100cm ? Running 50-80mph...
I read some guides about rake difference causing more and less bow lift, but if you could briefly tell me your experience and advice it would help me a lot.
I know there is no perfect prop, one have to test it with the specific boat and specify it s own preferences, but I hope for some general info what s the weakness and advantage of the props with more rake compared to those with less rake...

Kind regards
Vince

[Fluid]

You want low-lift props for a mono, so the 17* rake designs would be your choice. The 10* designs have more lift, not desirable in a mono. BTW, in model boats a “low-lift prop” means the opposite from what it does in full-size boats, here it refers to not lifting the transom, rather than the bow.

[Vinbul]

Hi Fluid. Thanks for your advice. I will order the 17* rake props.
But just to understand it : Why is more lift not desirable for a mono ? Lift pushes the hull (transom) up so is there no advantage ? Deep v monos have anyway some trouble coming out of the water to float.
Do Cats and F1 hulls also prefer less lift ?
Which hull would go better with a 10* rake ?

[srislash]

Hi Fluid. Thanks for your advice. I will order the 17* rake props.
But just to understand it : Why is more lift not desirable for a mono ? Lift pushes the hull (transom) up so is there no advantage ? Deep v monos have anyway some trouble coming out of the water to float.
Do Cats and F1 hulls also prefer less lift ?
Which hull would go better with a 10* rake ?

Lifting the transom on a V will result in a heavy bow which causes poor handling characteristics. Cats CG can be played with and MAY like a 10* rake but primarily Hydro’s use lifting props

[Fluid]

Too, high-rake props generate a smaller, more focused thrust cone, more efficient than that of lifting props. Watch some really fast SAW boats sometime, their roostertail is low and flat, indicative of the small thrust cone. Big tall roostertails might seem impressive, but they are actually the slow way around.

[Vinbul]

Thank you guys. U helped me a lot.

[Vinbul]

Just some more advice please : how is it with hydroplanes ? I have a 94cm Roundnose. What prop should do best ? More or less lift ? Octura X Series, Prather or ABC ( 17* or 10* Rake ?)

[Vinbul]

My set up is : 12S with SSS 4092 720KV. So to reach 100kmh I would need a Prop with around 80cm pitch.

My idea:

- ABC 1817/2 17* (77,7cm)
- ABC 2214/2 10* (78,26cm)
-ABC 2115/2 17* (79,95cm)
-Prather S235 (81cm)

Which one would you recommend ?

I have no idea if lift is good for a hydro (haven t tried it yet), but I think torque could help to press it more to the right side, so the right turns would be better ...?

[Fluid]

The 2115 should work well. Hydros do well with lifting props, but the low lift/high rake props are more efficient. You add a bit of down angle at the prop end to compensate....just a degree or two.



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[Vinbul]

Thank you fluid. Very good explanation. Now I just have to decide if I go the easy way with a lifting prop ( 2214 10*) or try to have the best efficiency by producing some lift (2115 17*) with the angle...