Another prop question

[LOVE6S]

Whats the diff between a 2 blade prop and a 3 blade prop of the same size and pitch, will one work better or slip less, will one draw more amps?

[Fluid]

The 3-bladed prop will draw more amps. The typical conversion is to use a 3-blade that is ~80% of the diameter of a 2-blade. This helps when prop walk or torque is a problem when turning - the smaller diameter 3-blade will cause less torque reaction.






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[LOVE6S]

It sounds like a 3 blade pushes as much water, but smother, actually more water, as you size down by 20%. Why is it then that 2 blade seems to be what most people use, or am I wrong about that?

[egneg]

The 2 blade props tend to be a faster prop.

[LOVE6S]

The 2 blade props tend to be a faster prop.

I can see how it would probally get a better bite.

[banixj]

usually the 3blades prop is used to put down the boat front...
so it's for correct a weight setup...
but you need more amps...

[Fluid]

The number of blades has nothing to do with the prop's lifting characteristics...raising or lowering the bow. That is controlled by blade shape, prop rake, pitch, etc. Two-blade props are much more popular because they are cheaper and easier to make, easier to modify, can give higher speeds (although the fastest R/C boat in the world ran a 3-bladed prop) and work very well. Sometimes the extra diameter of the 2-blade is an advantage, as in rough water where more of the prop blade remains in the water when bouncing.


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[SweetAccord]

A larger prop increases load. Increased Load will result in an increased current draw. A smaller prop will decrease current draw. Higher prop pitch will increase current draw, a lower prop pitch will decrease current draw.


Larger Props may create stability issues, make it difficult in corners and create torque steer. An advantage to using a larger prop at slower speeds is thrust. Acceleration on plane will be much greater. Efficiency is also higher for larger props as there is less possible slippage.


Smaller props may have higher levels of slippage, slower acceleration out of the hole but have several advantages. They are typically more stable and handle well in corners, and don’t veer the hull off course under hard acceleration. (torque steer)

Advantages: 2 Blade vs. 3 Blade when diameter and pitch are equal.

2 Blade
- Higher Top Speed
- Less Load on motor
- Motor will turn higher RPM’s

3 Blade
- Higher thrust / Faster Acceleration
- Increased Stability and cornering
- Higher Lift Characteristics