Folding or feathering propeller

[banshee]

Ahoy, all. My 2005 Catalina 34 MKII has a Variprofile prop that needs to be replaced. The company that makes them has been literally bombed out in Ukraine. Which propellers are you using and happy with? Thanks, Joe

[Breakin Away]

I've had a Flexofold 15"x9" 3-blade on my MkII since 2019. I've been VERY happy with it. Low maintenance (no lubrication or adjustments), simple design that is almost fool-proof (very large gears inside, so very difficult for hard growth to foul the inner workings). This year I took off the anode to acid-clean the oxidation and polish the contact points for good electrical continuity, but after 4 years the anode has plenty of life left in it, and replacements are readily available. I've never had to disassemble the prop - removing the anode is the closest thing I've done to disassembly.

I would make sure your shaft taper stops no more than 1" behind the aft end of the strut, since the prop hub is HEAVY and could cause shaft whip if that length of shaft is too long. Shaft whip is also less likely if your shaft is stainless than if it is bronze (stiffer metal is better). Although the prop extends back further toward the rudder, I have plenty of clearance between the prop and the rudder.

I would not recommend the 2-blade Flexofold. Although it is less expensive, and smaller so it folds up tighter for less friction when sailing, there is a case of a guy who could not get it to deploy when putting it in gear. It seems that it folded up so tight that there was not sufficient centrifugal force to deploy it in reverse. The guy put a number of videos of the problem on Youtube, so you can look for it there if you are curious.  https://youtu.be/3_adsflxy8g  But the 3-blade doesn't quite fold up as tight, so there's more centrifugal force to make it deploy in both forward and reverse.

If you install any new prop, make sure to follow Maine Sail's instructions on how to use lapping compound to ensure perfect mating between the prop and shaft.

[Ron Hill]

ban : you should be able to up the pitch to 10" without any problem!!

A thought

[Breakin Away]

ban : you should be able to up the pitch to 10" without any problem!!

This has been discussed before when I selected my Flexofold prop. I suggest that the original poster go back and look at my explanation why our more powerful MkII M35B engines should actually have a lower pitch prop than your smaller engine. https://c34.org/bbs/index.php/topic,10205.msg78626.html#msg78626

The M35B engines were paired with a transmission that has a more aggressive gear ratio, so the prop spins 15% faster at a given engine RPM, which loads down the engine more, requiring lower pitch. In addition to that, the Flexofold has a blade design that generates more thrust at a given RPM than other props, which further increases the load on the engine. In my case, my maximum RPM went from 3400 with the Michigan Sailer 15x9 to 3100 with the Flexofold 15x9, hard evidence that the Flexofold pitch should be 15x9. John Langford had a 15x10 Flexofold on his MkII and reported problems with it requiring it to be adjusted back to 15x9. (Check the link for the quote.) Bottom line: The MkII boats are a different powertrain, and the Flexofold also loads down the engine more than other props of equivalent pitch.

If original poster chooses Flexofold 3-blade, I'd recommend 15x9. But he's welcome to do whatever he wants, and the pitch setting on his current prop could also help guide his decision.

[Noah]

My Flexofold 3-blade 15x10 is a good match for my smaller 25XP engine with a Hurth 50 transmission. However, it still buries the sugar scoop transom (through-hulls) a bit at high RPMs.

[Dave DeAre]

When I bought my 2002 MK2, I had a Flex-o-Fold 15x10 installed, at the recommendation from Flex-o-Fold. The boat ran too fast at idle making docking and close maneuvers difficult. I bought and had 15x9 blades installed, much better and did not notice any difference in motoring speed. Have had the 15x9 for 12 years now recommend this size for the MK2.

If anyone wants 15x10 blades, let me know.

[banshee]

Ahoy all!! THANKS FOR YOUR INPUT......I will start shopping and install this fall...Joe

[pbyrne]

I have a variprop 3 blade.  I'm uncertain of the pitch, as it came with the boat.

But, I can say it provides good thrust, never is an issue going between forward and reverse, and it's very well made.  It's a lovely piece of engineering.  It probably the only thing on the boat I actually look forward to servicing!  No idea why...

It does need to be greased seasonally though.

[Jim Hardesty]

I've had a Maxprop for about 20 years.  It's been flawless. Great thrust, low drag.  I say it's the best sail change I've ever done.  As for thrust, I towed a 42 foot sailboat over 200 miles without a problem, mostly over 5 knots.  We do have a winter lay-up in Erie,Pa so annual lube is not an issue for me.  I'm no expert on props, but it seems to me that the wider the prop blade the greater the thrust.  Like having wider tires.  Been on other boats with the 2 thin blade folding props and they seem to struggle with the steep Lake Erie waves.
Jim