Two or 3 blade prop for less prop-walk

[oldharry]

I went from 2 to 3 blade on my 24 footer. A signifiucant improvement in power and handling boith forward and astern. The 2 blader created serious prop walk, which almost cmpletely disappeared with the 3 blades. No, I didnt expect it either!

 

[RivalRedwing]

You can go port or starboard if you get a long-keeler with the prop operating in a cut-out in the rudder. Which of the two ways it goes is always a surprise, mind!

And what is this 'going dead astern' of which you speak?

The key is adopting an air of indifference along with preplanned options A & B

 

[adwuk]

We had a 2 bladed fixed and switched to a 3 bladed featherstream. Prop walk is reduced, so much so that we can now steer back in a straight line and even get a slight reverse turn to starboard with full starboard rudder - a feat that was previously impossible.

 

[LittleSister]

The key is adopting an air of indifference along with preplanned options A & B

At which point the boat demonstrates its own indifference and proceeds to implement option C!

 

[Bobc]

We had a 2 bladed fixed and switched to a 3 bladed featherstream. Prop walk is reduced, so much so that we can now steer back in a straight line and even get a slight reverse turn to starboard with full starboard rudder - a feat that was previously impossible.

That has been my experience too, which is why I recommended it to the OP.

 

[eddystone]

Can I suggest that your best bet would be a 3 blade Featherstream.

I had similar reversing characteristics om my boat and now it goes wherever I want it to.

I have a similar experience with a Featherstream OTOH the prop walk has weakened, which could be useful at times.

 

[Laminar Flow]

A two bladed prop versus a 3 blade will have a larger diametre to maintain blade area. This will reduce clearances and in this particular case, to the hull, thus reducing flow over the top of the prop, compared to the bottom. It is the pressure differential that causes the propwalk. Conversely, switching to a 3 blade reduces propwalk by increasing clearance.
The most ideal prop would have but a single blde, but for obvious reasons the ride would be a bit bumpy. Next is a 2 blade but sufficient diametre can be difficult to achieve, when space restrictions, tip velocity issues that lead to cavitation, maintaining blade area to keep blade loading at a reasonable level, tend to set practical limits. A two bladed prop on a sailing boat is generally chosen to limit impact on sailing performance at the expense of that under power.

 

[Stemar]

At which point the boat demonstrates its own indifference and proceeds to implement option C!

As someone put it once, "How's your boat going astern?" "No problem, we let her do what she wants and pretend we meant it"