Propeller choice

[mick]

I am thinking of buying a Flexofold prop for my Hallberg Rassy to match a Volvo Penta D1-20. The Flexofold website says,
"A 2-blade propeller is more efficient than a 3-blade. Surprised? Well, most people are.
Thus, a properly sized 2-blade will give you a higher speed at a given RPM in flat water than a properly sized 3-blade. The 2-blade is also lower in drag and cheaper.

The 3-blade, because of its larger blade area, will accelerate the boat faster. This means a 3-blade is better around the docks, when powering against a head sea and when stopping."

The Yachting Monthly report seems to suggest there's very little difference in performance between two- and three-blade. The 2 blade is only slightly cheaper. All comments appreciated.

 

[mick]

I forgot to say the boat is a 29.

 

[Tranona]

Think you will find the 2 blade will be more tthan adequate. I have one on a Bavaria 37 and performance is very similar to the fixed prop it replaced. The only thing you have to get used to is the slight delay when you select reverse before the blades open - common to most folding props. The trick is to give a quick burst of revs rather than just dropping in at tickover. Once the blades are open thrust is the same as the fixed prop.

One advantage of the 2 blade is that it is much simpler than 3 and does not have an anode. Suprised you say the 3 blade is not much more - I thought when I was looking that it was substantially more expensive.

 

[mick]

Suprised you say the 3 blade is not much more - I thought when I was looking that it was substantially more expensive.

You're right, the 3 is a good bit more - bit of festive misreading there.

 

[JimC]

I fitted a FlexoFold 2 blader to my Hunter Channel 31 to replace the Radice fixed 2 blader that Hunters fitted as standard. I am very pleased with the FlexoFold, it is an improvement in every way including stopping and reversing where folding props are popularly supposed to struggle. I got it from Darglow Engineering. Interestingly they specified a finer pitch (16 x 11) than the Radice had (16 x 12). I think this was because the broader blades of the FlexoFold get a better grip on the water and experience less slip. They reccommended 2 blades in preference to 3.

 

[mick]

Thanks, chaps. Flexofold it is.

 

[mick]

2-blade that is.

 

[cmedsailor]

If your Halberg Rassy has a shaft and a skeg (like bigger models) check if the 2 blades will cause vibrations. If you already have a 2 blader and no vibrations then you are OK.

 

[mick]

If your Halberg Rassy has a shaft and a skeg (like bigger models) check if the 2 blades will cause vibrations. If you already have a 2 blader and no vibrations then you are OK.

Saildrive