Propellors: Folding? Feathering? Folly?

[sailmed]

Since my previous post, George Bean has rightly convinced me to forgo the a-kite and put my $$ into a good prop.
George seems pleased with the 3 blade FlexoFold and his input has been very helpful. It seems that, the more I look into it, the more obscure is the answer to the question..."what prop to buy?" 
From what I can garner, a two blade folder is more efficient in relatively calm water, but suffers in heavy current or headwinds, where the punch of a 3 blade prevails.  Two blades offer the least resistance when folded, but the Gori 3 blade is pretty darn slick when folded.  This, of course is if the prop shaft is parallel to the direction of motion, and does not account for downward angulation of the prop shaft, in which case a different profile is presented to the flowing water.  The two blade may suffer from pulsation induced vibration against the underside of the hull, depending upon how close the blade tips are to it.  The 3 blade folder stops better than the two, and the feathering (and maybe the Gori) stops better than that.  The feathering and the Gori have a proper leading edge in both forward and reverse, reducing prop walk and improving stopping power.
I'm told that the Autoprop is quite good, as a feathering prop, but there may be issues of installation, as the blades flip over for reverse... their tips moving aft of the hub (great video of that in action on their website)
I would like to hear from some members who have any of these on their C34's.  What do you like, what do you dislike?  What would you buy if you had to again?
I have looked at previous posts on this issue, but they have not resolved it for me.
Many thanks, looking forward to taking delivery in early June, in Annapolis.

Barry Smoger
s/v LOON
Rock Hall

[Rick McCall]

I put on a Max Prop feathering 3 blade last year. It is great under power, no noticable prop-walk in reverse and awesome under sail. Just did my haul-out this week and prop was in great shape, zinc still had 85% life after 10 months (switched it anyways). The only issue I have is you have to get the zincs from PYI and they are a little more costly than standard. It does require a quick haul once a year to do the zinc and grease the prop. You could maybe get away with doing the zinc in the water and haul every 2nd year to grease.

I'm happy with the decision I made, did a lot of research and talked to a number of other local boaters with the max prop and they were happy as well. I'm not sure about the other brands, probably great too, I just couldn't find any local boaters that I knew that had experience with the other brands.

[Ron Hill]

Barry : Why not go with the 3 bladed fixed that comes with the boat from the factory??  Why spend many $$ to overcome a .4kt drag(less if you let the prop freewheel)?

You should up pitch the factory fixed 3 bladed from 15X9 to 15X10 or 11 as I did.  You have a prop that's dependable (NO moving parts) that is made/designed for the optimum speed forward!!  I back the boat just fine.  You learn to play the "backing to port", wind drift and current, with some practice.  You have to practice for the last two no matter what!!  A thought.   

[Ron Hill]

Barry : Another thing that I forgot to mention on the feathering/folding props is that you may have to modify your shaft!!  The hub on these props is larger to accommodate a mechanism, so like the MAX prop you might have to cut off 1/2+ inches off the threaded end of the shaft so things will fit! 
Kind of like "burning the bridge you just crossed".  A thought!   

[John Langford]

I just installed the "kiwi prop". It is a three bladed feathering prop with light composite blades which can be replaced for less than $100 each. The design is dead simple and there are no gears. No modification of the shaft is required and the installation was effortless. Because the blades are a composite material, you put antifouling paint on them. I have only had it out on the water for four days but there is noticeably less drag when sailing in winds of less than 10 knots (I previously had the three blade "sailor" prop. Equally interesting, at my normal cruising revs I have gained 1/2 knot in speed.It backs much more aggressively than the normal three blade and,my initial sense is, with less prop walk. Because it is so light (around 7 lbs I believe) there is no massive clunk when you engage the transmission, so bearing and strut wear should be minimal. For the M35B with the standard transmission they recommend a 15" prop with 21 degrees of blade offset.

Take a look if you are interested: http://www.kiwiprops.co.nz/

I got mine from West by North Enterprises which also handles the Campbell Sailor prop. They provide excellent, friendly service. See:http://www.westbynorth.com/

[Ron Hill]

Guys : FYI, You can fool around with prop pitch.  Maybe up to 11 inches for the M25XP and 12 inches for the M35.  A lugged down engine and black smoke will let you know if you over did it.

However, DO NOT let anyone convince you to increase the diameter above 15 inches.  A larger prop can cause buffeting against the bottom of the hull!!    

[Steve S.]

I have the flex-o-fold, so I can only discuss that vs the old 3 blade fixed.  Its pricey, but I really like it and I am glad I spent the money (what else would I use the money for? foof? shelter?)  The key improvements were:  1)  significantly reduced prop walk, which is important to me as I must turn to starboard when I back out of my slip, 2) it smoothed out the engine (less vibration at a larger range of RPM's), 3) better speed - ran about 6.1-6.3 knots at 2200 RPM on flat water, and last but not least, 4) 1/2 knot extra when under sail.

I used to have a drive-saver on the sahft but I removed it when I installed the flex-o-fold.  The FoF is very heavy so I wanted it as close to the cutlass as possible (now, I'm within a 1/2 inch) and being in Chesapeake bay, the risk if hitting a rock is fairly low.  Plus now, it is easier to align the shaft.     

[isabel98]

Flex o fold 2 blader is thumbs up all the way! They'll coach you when you order so as to get the right size/pitch.. very simple operation/insatallation.. slap it on wave bye-bye...

[Terry Forshier]

What size flex a fold propeller did you two buy? I think they make a 2 and a 3 blade prop. I have the XP25. on H #570. ??
Also the KiWi props talked about?? I could not get a price page. Terry

[Tony Benoit]

Hi,

I have a 3 bladed Flex-O-Fold on Helen C and like it fine.  The drag under sail is minimal and power in forward and reverse is good.  The boat stops quickly with reverse.  The tiny bit of prop walk is sometimes useful once you get used to it.

BTW, the transmission on the Universal diesel does not like being left in neutral when the boat is under sail.  I leave it in reverse, so have to remember to put it back neutral before starting up.

Thanks,

Tony
Helen C
'89 #903
Watch Hill, RI

[Jeff_McKinney]

Barry,

I think you are one of the newest 34's on the bay. I'm over in Bodkin Creek.

Just put on a Gori 15 x 10 prop on last month. Much improvement in output over the 15 x 9 fixed factory prop in both directions, almost no prop walk, and at least a knot faster sailing in 10-15 kts of wind. The other bonus is that when the blades fold up there is a much lower risk of snagging a crab pot. There IS still the risk of this when motoring, so I put on a Shaft-Shark (cutter). It fits on between the prop hub and the skeg that supports the shaft.

I still make an extra effort to avoig the crabbing areas, and so far have not (to my knowleddge) sliced one "yet", but I'm as ready as I can be. Will still keep the knife, snorkel & fins handy.

I guess it all comes down to what you want to do with your money. I also keep the old fixed prop stored below in case Mr. Murphy pays a visit. 

Tony: I routinely put mine in neutral for a few seconds to let the prop folds up, then stick it in reverse. Have not had any problems with it opening under sail.

[Robert Mann]

Ron, when you up pitched who did you purchase the prop from.  My boat has a Martec 2 blade folder.  Its noisey at low engine speed and is not helping during reversing the boat.  It also requires that the engine idle be set at a very low level and the vibration of the engine it high at idle, still a good clunk when the gear is engaged.  I fancy the idea of moving to a fixed 3 blade for the reasons you mention but I need to measure shaft details as it's not the original shaft, its stainless.  Guess why?  The original bronze shaft bent and I think it was due to the folder probably not opening at one time in its life.  Lots of correspondence between Catalina and PO!! I would like to do the prop swap in the water.