KAAMA

I have heard that adding some cup to a prop will help give more bow lift. What else does adding some cup to a prop do? Are there any disadvantages? Thanks in advance.

Mark/KAAMA

28Eliminator

Good Question KAAMA, I am interested in this as well because I think I need more bow lift , but I don't want to give anything up.
Come on prop guy's!

throttleup

KAAMA,

Adding cup to a prop will assist with bow lift. It will also improve acceleration. But it will also DECREASE RPM. There is a fine line with cupping .

Julie
Throttle Up Propellers

Tinkerer

adding cup will also help with lowering cruise rpm prop slip. This will increase cruise speed for the same RPM.

HOUSTONPROP

Mark There is a pitch section and a rake section to the cupping of a propeller .By adding cup in the pitch line or section this will theroitactlly add pitch. and by adding cup on the rake section (tip of the Blade will create additional bow lift,cupping is very critial but can be adjusted pretty easy yourself, if a experinced prop person tells you how. on a cleaver style propeller on the thick trailing edge you actually grind material out of the cup to increase the cup and blend back into the blade until its smooth as well you know and rolling cup on the tip can be done by mounting the prop to a soild base or old prop shaft welded to a table,and use a rolled brass hammer on the pushing side of the blade and use a ball pin on the other ,you may need to use some light heat,also you will leave some marks in the blades which can be removed by using a scoth brite pad in a small air angle grinder that home depots sells .sounds fun hope, I have helped out but this is how it's done in the propeller world. or just send it out and have it done . Darin

deboatmon

I have had cup professionaly added at Merc Racing Propellors and it works great for me. They also labbed the same 28 pitch Bravo 1's. The added cup seems to be most advantageous when higher drive heights are present.

My personal experience has been that with cup added, I can get on plane and accelerate much better than without it. Cup can have the same effect on the top end as adding pitch and that may not be a desirable thing for some. Adding substantial cup to a slightly less pitched prop might even out on the top end and could help acceleration greatly if you are experiencing any blowout under hard acceleration. If your most valued thing is cruising rpm, having cup added to your prop might be the way to go.

audacity

KAAMA....let me know when your ready to dial in...i may know a thing or two!!LOL

just don't start messing with your props like that!.....it's always a give and take....but like juile will tell you....i give up NOTHING!....lol....but we do spend a lot of time fining and correcting that "fine line!"

HOUSTONPROP

You are right on the money,you know whats up and not really suggesting to work the cup your self unless you have some experince with air tools ect,Darin

bvs629

Darin,

What would be the difference between Mirage Plus 23's
and the same prop cleavered.
On a 29 baja outlaw. 7.4 mpi, 310 hp each
Mirage 23's wot 4600 rpm, 64 mph?

V/r,,

BVS629

HOUSTONPROP

The cleaver props are surface piercing, and produce stern lift and are alot slower on plane, such as a mirage, which is Bow lifting and quicker on plane. A cleaver style prop runs smoother in large seas, also keeping the boat up and out running, on the tips of the blds (if you have enough motor). The cleaver props tend to be slower in accleration, as the Mirage will come on faster and harder in mid range/Ihope you understand my lingo