# Beneteau 473 prop zize



## tomaz_423 (Feb 5, 2006)

I am thinking of replacing stock 3 blade prop on my Beneteau 473 with a folding or feathering prop.
It is cold here and I can't dive under my boat.
Does anyone know what is the size and pitch of a standard 3 blade Beneteau puts on 473 year 2005 ?
I have a standard 75 HP Yanmar (4JH3-TE) on the boat and the prop is original from the factory.
Another questions:
What size you think I should mount?
What size is max possible for my boat?

What do you think of Flexofold for this boat and what about Autoprop? Any other recommendation?


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## Fstbttms (Feb 25, 2003)

I'd say go with Gori or Flex-O-Fold if you want a folder. Max Prop if you want a feathering prop. Stay away from Autoprop. 

That's my $.02.


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## MJBrown (Apr 1, 2009)

Can't tell you what size the 473 takes but can tell you we had an Autoprop on our last boat a Bene 361 and loved it. Never an issue with plenty of power when motoring in fwd or reverse, nor with lower drag while sailing. I wouldn't hesitate to get another although will shop to see what else is out there when the time comes.


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## sailingdog (Mar 19, 2006)

Another option would be a Kiwi Prop for a feathering prop. You could always call Bendytoy and ask them for the prop specifications.


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## blt2ski (May 5, 2005)

I would figure out the prop you want, then deal with the prop manufacture to figure out the prop size based on motor, transmission gear, and RPM of the motor. Then you decide if you want a 2, 3 or 4 blade! No real need to know what you current prop size is, as the prop you buy, may have a different pitch or even diam to what you have.

Marty


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## Minnewaska (Feb 21, 2010)

If I recall, Kiwi props are composite material (plastic maybe?). I'm very happy with my Max Prop, which is all metal. I guess the composite doesn't corrode, but the metal doesn't break (for the most part).

I agree that you should determine which prop you want, then call the manufacturer. Max Prop, for example, can be installed with several different settings to accommodate different pitches. You simply line up the gears differently.


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## Fstbttms (Feb 25, 2003)

Minnewaska said:


> If I recall, Kiwi props are composite material (plastic maybe?). I'm very happy with my Max Prop, which is all metal. I guess the composite doesn't corrode, but the metal doesn't break (for the most part)..


Kiwi Prop blades are designed to break if damaged and are easily replaceable.


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## tomaz_423 (Feb 5, 2006)

Than you all for answers so far, specially to you Fast.
You have probably seen a few props in the water.

Kiwi: max engine power for them is 55 HP, mine is 75, so they are out.

I liked Gori's overdrive function, but some people told me it is not that practical.

I also liked Autoprop automatic pitch, but again heard a few not so good comments.

All props are a compromise. Fix prop on a sailboat must compromise between drag while sailing and propulsion while motoring.

Folding props do not have this drag problem (but must still fit into the opening available).

Flexofold sized the prop for my boat as 20x12 3blade.
I do not know if they took same size as stock Bene prop and just reduced drag or they optimized it for better motoring performance as well.

Autoprop sized it at 485mm (about 19 inch)

Prop calculator on 
Sail Calculator Pro v3.53 - 2000+ boats 
recommends 23.8 inch

Of course I trust Flexofold sizing more then a free internet calculator, but still - it is a big difference between 20 and almost 24 inches.

Flexofold shows this article on their site: http://www.flexofold.com/upload_dir/docs/Test_YachtingMonthly_low.pdf

Any more ideas?


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## Fstbttms (Feb 25, 2003)

tomaz_423 said:


> Thank you all for answers so far, specially to you Fast.
> You have probably seen a few props in the water.


I have installed quite a few Goris on Beneteaus as well, as the local dealer here offers them as an option on new boats.


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## blt2ski (May 5, 2005)

Tomaz,

Check with Zanshin, IIRC he has an autoprop on his 49' Jeanneau. Could be worth a pm or to to see how that is functioning or him.

I have a max prop, like all, has plus's and minus's. I know another fellow with an identical boat to mine, he removed the max prop as it went haywire, went to a fixed, and got double the fuel mileage if you will. I would think a light prop would be better for lack of fuel use. 

Marty


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## Fstbttms (Feb 25, 2003)

blt2ski said:


> I have a max prop, like all, has plus's and minus's. I know another fellow with an identical boat to mine, he removed the max prop as it went haywire...


No offense, but this sounds like inaccurate hearsay. A Max Prop went "haywire"? What exactly does that mean? Max Props are among the best engineered, most robust feathering props made and I'm not sure I have ever heard of one failing.



blt2ski said:


> (He) went to a fixed, and got double the fuel mileage if you will. I would think a light prop would be better for lack of fuel use.


Again, this sounds unlikely. Your friend reduced his fuel consuption by half when he went to a fixed blade prop? If true, it sounds like his Max Prop was pitched incorrectly.

Again, I mean no offense, but both of these comments are so out of left field (as far as Max Prop is concerned) that I'm a bit skeptical about their veracity.


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## blt2ski (May 5, 2005)

I do not recall what went on the max prop. it made sense at the time.........
I do about a gal an hr which is what he mentioned with, and about 1/2 gl per hr with a fixed. The only thing I can figure on the fuel part is the wt of the prop itself was the issue. There are some internals that do need to be replaced IIRC upon occasion, and this is what I recall failing. It could also have been a $$ issue to rebuild it, and he did not want to spend the money. 

My max prop has been going for some 15 yrs with out a hitch and I would get another, altho for my boat I would go with a triple over the double for a bit more bight when motoring into the currents I have here on puget sound. 

Marty


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## Fstbttms (Feb 25, 2003)

blt2ski said:


> I do not recall what went on the max prop. it made sense at the time.........
> I do about a gal an hr which is what he mentioned with, and about 1/2 gl per hr with a fixed. The only thing I can figure on the fuel part is the wt of the prop itself was the issue. There are some internals that do need to be replaced IIRC upon occasion, and this is what I recall failing. It could also have been a $$ issue to rebuild it, and he did not want to spend the money.


Max Props typically do not need to have any parts replaced at any time during their decades-long useful lifespan. They do require periodic lubrication. Refurbishing is also something that can bring a well-used Max Prop back to life. Regarding the weight issue, it seems unlikely that a Max Prop (which would only outwiegh a like-sized fixed-blade prop by maybe 10 pounds, if that) would reduce fuel efficiency by 50%, IMHO.


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## LakeSuperiorGeezer (Oct 8, 2010)

Be careful going with larger propeller sizes because of cavitation (do not confuse with ventilation). Cavitation is vaporization of water, a low temperature boiling forming bubbles, caused by excessive reduction of pressure on the aft side of a propeller, which can cause physical damage to the blade surface when the bubbles collapse. For a given engine and gearbox, the propeller tip speed increases rapidly with increasingly larger diameter.


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## blt2ski (May 5, 2005)

FB,

It is possible he did not lube the prop enough, and it froze up and here we are discussing the issues with MP's! As you say, they see to have a bullet proof record about them. 

I would also agree, that .5 to a 1 gal difference seems extreme. I was thinking the MP was 3-5 lbs more than a fixed, it could be 10 as you say. A heavier prop will use more fuel, I feel a cup or two per gal would be reasonable, but 2 qts or 8 cups does seem like a lot. I have no experience on my boat in the difference of fuel useage. as the MP was ON the boat when I bought her. I luv it frankly. I am going to increase the pitch one notch the next time I haul, to see if I can get some more speed. The paperwork I have shows proper pitch/degree's per MP, PYI talking to them feel I could increase the pitch from 18 to 20 or some such amount from memory. We will see what that does. I have the notes elsewhere for my setup.

Marty


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## LakeSuperiorGeezer (Oct 8, 2010)

*Fuel Consumption & Prop Maintenance*



Fstbttms said:


> Max Props typically do not need to have any parts replaced at any time during their decades-long useful lifespan. They do require periodic lubrication. Refurbishing is also something that can bring a well-used Max Prop back to life. Regarding the weight issue, it seems unlikely that a Max Prop (which would only outweigh a like-sized fixed-blade prop by maybe 10 pounds, if that) would reduce fuel efficiency by 50%, IMHO.


If maintenance were neglected, then it is likely the prop would need servicing before its normal lifespan was exceeded. What might have happened is the pitch froze in a position that was too great, working the engine hard, perhaps at lower RPM, while trying to push the boat beyond hull speed. Another possibility is if the pitch were really excessive, it might even be possible for the propeller to stall at the low speed a sailboat would move at resulting in great inefficency.


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## Fstbttms (Feb 25, 2003)

blt2ski said:


> I am going to increase the pitch one notch the next time I haul, to see if I can get some more speed. The paperwork I have shows proper pitch/degree's per MP, PYI talking to them feel I could increase the pitch from 18 to 20 or some such amount from memory. We will see what that does.


No need to wait for a haulout to repitch your Max Prop. Call PYI, they will gladly recommend a qualified diver local to you who can do it at your slip.


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## blt2ski (May 5, 2005)

Fstbttms said:


> No need to wait for a haulout to repitch your Max Prop. Call PYI, they will gladly recommend a qualified diver local to you who can do it at your slip.


I've got to do a survey haulout by February, so will probably do it then. ALong with will probably need a bottom paint job. It is not on the high priority things of what needs to get done. I need to get an LP electric wire switch by the stove and shutoff at the tank before, or will get dinged. Otherwise, I should be in good shape for the survey.

I know of a couple of local divers that can fiddle with the MP while in the water.

marty


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## Minnewaska (Feb 21, 2010)

Fstbttms said:


> No need to wait for a haulout to repitch your Max Prop. Call PYI, they will gladly recommend a qualified diver local to you who can do it at your slip.


That sounds like a royal PIA, but I'm sure its done all the time. Its a two handed job when you don't have to maintain buoyancy.

I believe the gear/letter alignment for pitch changes is done while assembling the prop on the shaft, piece by piece. I don't think you can remove/install a fully assembled unit, therefore, is getting salt water inside the gears a bad idea?

I know you can pump grease through it to theoretically force it out, but I would opt for doing on the lift if it were an option.


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## Fstbttms (Feb 25, 2003)

Minnewaska said:


> That sounds like a royal PIA, but I'm sure its done all the time. Its a two handed job when you don't have to maintain buoyancy.


You're right about one thing- it is done all the time.



Minnewaska said:


> I believe the gear/letter alignment for pitch changes is done while assembling the prop on the shaft, piece by piece. I don't think you can remove/install a fully assembled unit, therefore, is getting salt water inside the gears a bad idea?.


Are you under the impression that Max Prop (or any feathering prop) is watertight? It is not. It is not designed to be. And as the entire prop, every piece of it (inside and out) is made of the same material, the internal parts are not more suceptible to saltwater than the outer parts.



Minnewaska said:


> I know you can pump grease through it to theoretically force it out, but I would opt for doing on the lift if it were an option.


Hey, it's your dime. Knock yourself out.


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## Minnewaska (Feb 21, 2010)

Fstbttms said:


> Are you under the impression that Max Prop (or any feathering prop) is watertight? ....


Nope, when I grease mine at the end of the season, on land, the grease always displaces some seawater. It isn't that much. Obviously, if you assemble underwater, it all must be pushed out. I have to wonder if the grease, twist, grease again, method really would push it all out. I understand that trapped seawater is worse for metal than open water.


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## Fstbttms (Feb 25, 2003)

In normal operation, the Max Prop has a certain amount of seawater in the interior cavities. It was not designed to be "packed" with grease. It would not operate properly if you put enough grease in it to displace all the water.

You are barking up the wrong tree here. Not only is it perfectly acceptable to install or repitch a Max Prop underwater but PYI recommends it. There is no reason to haul a boat to perform installation, removal or other maintenance of *any* prop, fixed, feathering or folding.


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## Minnewaska (Feb 21, 2010)

Fstbttms said:


> ....You are barking up the wrong tree here. Not only is it perfectly acceptable to install or repitch a Max Prop underwater but PYI recommends it.....


Not sure what barking you've heard. In my original reply to the underwater install, I phrased the issue of salt water on the gears as a question.

I assume you mean that PYI authorizes underwater installs. I have the installation instructions and don't see where they recommend you do it in the water.


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## Fstbttms (Feb 25, 2003)

Minnewaska said:


> Not sure what barking you've heard. In my original reply to the underwater install, I phrased the issue of salt water on the gears as a question.


I was referring to your obvious inference that underwater Max Prop installations have definite drawbacks, which they do not.



Minnewaska said:


> I assume you mean that PYI authorizes underwater installs. I have the installation instructions and don't see where they recommend you do it in the water.


You are correct, the instruction manual (not written by PYI, BTW, they are simply the North American distributor of Max Prop) describes the installation procedure with the assumption that the boat is on the hard. If you call PYI and ask about R&R options however, they will tell you that it can be done underwater and will refer you to their diver of choice in your area.


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## tomaz_423 (Feb 5, 2006)

Flex-O-Fold clearly advocates underwater or out ow water assembly in their manual. Their only consideration is which thread locker you use.
From their installation manual for 3 blade shaft drive: 
Quote: Thread locker:
There is an underwater proof thread locker pre-applied on all screws in the installation. These screws can be instal-led out of or under the water.
Normal fluidic thread locker is not designed to be applied or cure under water and attempts to apply it under water will ultimately fail. Nor can regular thread locker be applied to the thread in air and allowed to cure before the screw is mounted under water. There will be no adhesion.
If removing the propeller underwater for any reason, do not reuse the screws when mounting again under the water. Please contact Flexofold for replacement screws that have the pre-applied thread locker.
When reusing the screws out of the water, make sure to apply a medium strength version of thread locker such as Loctite 243 (blue). (end of quote)

*Fast,* just from curiosity:
I looked at Flex-O-Fold manual and there are a lot of little pieces to assemble. 
A lot of marinas have murky water and mud soft bottom. How do you protect yourself against loss of small items? I drop little screws on hard all the time, I imagine that underwater must be harder not to drop anything.
Do you spread something (a fine net or cloth) below the work area to ever find the item again or are you super careful not to drop anything?


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## Fstbttms (Feb 25, 2003)

tomaz_423 said:


> *Fast,* just from curiosity:
> I looked at Flex-O-Fold manual and there are a lot of little pieces to assemble.
> A lot of marinas have murky water and mud soft bottom. How do you protect yourself against loss of small items? I drop little screws on hard all the time, I imagine that underwater must be harder not to drop anything.
> Do you spread something (a fine net or cloth) below the work area to ever find the item again or are you super careful not to drop anything?


I built a 3'X4' frame out of 1" PVC pipe and stretched mesh material across it. I ballast each corner with a zinc and lower it to the bottom under the prop. That way, if I drop a part, it lands in the "safety net" and not the mud.


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