# What are the pros/cons of the Max Prop



## MedSailor (Mar 30, 2008)

Some of the boats I am looking at buying have a Max Prop. One of these puppies was historically never in my price range, so I never learned much about them. 

My limited understanding is that they fold the blades when sailing to reduce drag under sail (a good thing) and that they reverse the blade pitch in reverse to increase power in reverse (a good thing) and that they are expensive and add complexity and possibly more failure points (a bad thing).

Is the above generally true? Is there more to it than that? Does one loose efficiency in forward? Do they constantly adjust pitch at different RPMs or are they "fixed pitch" when operating? Do they help with prop walk?

Thanks. As you can see, I don't know much about these props, so any advice or opinions would be useful.

MedSailor


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## erps (Aug 2, 2006)

We have one on Nikko. Came with the boat. Sometimes it takes a couple tries to feather the prop when we transition from motoring to sailing. They don't have hardly any prop walk which I actually kind of miss. I can't keep the cone zinc on it for more than six to nine months. When they start to wear, the bolts that hold it on get loose and it throws itself off. We keep the shaft zinc'ed as well, so I don't worry too much about electrolysis. It's the only feathering/folding prop I've had, so I can't compare it to other props. I've been told that it has much better reverse performance that folding props.


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## jsaronson (Dec 13, 2011)

I have a 25 year old model. I had it reconditioned this winter. PO did not keep records, so I have no idea when it was last done. (Manual said 1997!) Cost was about $400. I've never had another prop on this boat, but I'm very happy with it. There are not a lot of moving parts, so I would think failure is highly unlikely unless you hit something.

The newer ones can be adjusted while on the boat. Mine needs to be disassembled on the hard. Good luck with the search!


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## Don L (Aug 8, 2008)

I had a MaxProp on my last boat and when I got my current one was going to get another feathering prop. But after research decided based on all the tests I could find that the "advantages" of a feathering prop over a folding prop were pretty minor almost to the point of make believe. So I got a Flex-O-Fold prop instead. Based on my experience the differences are:
- the Flex-O-Fold was over $1000 less expense
- the Flex-O-Fold is way less complex
- the Flex-O-Fold seems to be just as good in reverse (what is suppose to be the advantage of the MaxProp)
- the Flex-O-Fold is WAY more efficient in forward and uses a LOT less fuel for the same boat speed even though it is on a bigger boat
- the Flex-O-Fold doesn't need maintenance other than new zincs

In the end I wanted to reduce drag while sailing, have the least complex prop to do it, spend the least amount of money, have reasonable power and control in reverse; the Flex-O-Fold 3 blade prop I got did all these for me.


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## arf145 (Jul 25, 2007)

I was lucky enough to have the previous owner spring for my MaxProp. Yes, more complex than standard, but it seems like a very solid, relatively simple piece of gear. Maintenance consists of refilling with grease through the grease port every two years.


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## mr_f (Oct 29, 2011)

We had a 2-bladed folding on the last boat, and a 3-blade max-prop on the current, both courtesy of the previous owners. The most noticeable difference for me was the performance in reverse. Really quite an amazing difference. Mine definitely has some prop walk, although less than the old folder. 

As for the cone zinc, apparently there are two versions available. On the original (and still commonly available) version, the zinc around the bolts is sacrificed quickly causing it to loosen up as noted above. The improved version has reinforcement using a different metal near the bolts to reduce that problem. This is my first of the improved zinc, so we will see. 

Mine required about $700 in rebuild cost at 10 years old. I don't know if it was serviced before that (besides the yearly grease) but I imagine it was not.


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## RichH (Jul 10, 2000)

Im DELIGHTED with the performance of my (short hub) Max-Prop. 
Ive 'repitched' several times and can state emphatically that my engine is now 'maxed' because of the Max Prop, etc. etc. etc. 

Only downside, is that the blades do become 'wobbly' after a few years (due to reversing/forwarding) ... but ~$400 is a reasonable cost to 'rebuild'. 
The 'improved' cone zincs are TERRIFIC - long lasting.


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## capta (Jun 27, 2011)

I have used a number of folding props in the past and generally was unhappy with their performance under sail or power. However, this boat came with a complete MaxProp, in a bag, and I decided to try it out.
It is absolutely marvelous. No longer do I need the hydraulic shaft brake, and the wheel isn't spinning for hours at a time, under way. It feathers easily and if it's cranky (if we're sailing above 7 knots, sometimes it won't feather), just shut down in forward and it always feathers then. Unlike most folding props, the MaxProp does not rely on centrifugal force to open; it has gears which force the blades open, in both forward and reverse, so it should (it hasn't in 3+ years) never fail to open, and it will not fold when motorsailing.
As mentioned above, with a lot of use, it does need the occasional servicing from the factory, but don't you have to have a fixed prop balanced every so often, as well?


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## Alex W (Nov 1, 2012)

I switched from a fixed prop to a Featherstream prop a few months ago. I also considered the Max-Prop and Flex-O-Fold. The Featherstream and Flex-O-Fold prices were very similar and the Flex-O-Fold agent was very unhelpful. The Featherstream agent was extremely helpful, as was PYI when I asked about the Max-Prop.

The Featherstream is made by Darglow, the UK Max-Prop importer. It is very similar to Max-Prop, but pitch is adjusted differently. I've also sailed on boats with a Max-Prop and helped a friend adjust a 3-blade one.

The sailing performance improvement is great. It is easy to measure, if you leave the engine in neutral after going forward the prop will freewheel just like a normal bladed prop. Put it into reverse to lock the blades and in normal sailing conditions the boat will speed up by half a knot to a knot depending on the wind conditions. That is a great improvement!

I haven't done enough cruising on the Featherstream to see how fuel economy will compare to my previous Campbell Sailor prop. I don't notice any difference in motoring performance and have never had trouble getting the prop to go into forward or reverse.

The devices are pretty simple internally and as long as they are kept lubed I see little that can really go wrong. I do have an old 2-blade prop that I will carry onboard as a spare when cruising. I doubt that I'll ever need it, but it provides a bit of peace of mind and doesn't take up much space.


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## lancelot9898 (Dec 30, 2008)

I installed a new max prop on my boat in 1985 and it has served me well over those years. Every 2 to 3 years when I haul the boat, I repack the gears with grease and I usually need help in doing that. Many of the newer ones have zirks fitting so that grease can easily be added without disassembly. Also there may be easier ways on newer models to adjust the pitch rather than complete disassembly which I have to do if I want a new pitch. The pitch adjustment allows some fine tuning to hit a sweet spot on the engine rpm, however note that the pitch is constant once set and an variable pitch prop would be a better performer, but is more complex. Besides having the advantage of experimenting with pitch, the reverse thrust is a huge advantage when docking. I also still have prop walk which someone else said they did not. I consider prop walk as a advantage. There is some loss of efficiency in forward since the blades are flat vs a curved blade of the fixed prop. Not sure how significant that is. 

I'm happy with the performance and have noticed recently some wobble in the blades and did not know that maybe that can be improved. Not bad for close to 30 years of use including some ICW motoring trips.


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## Ilenart (Jul 23, 2007)

I have a two blade Autostream feather prop which looks similar to the Maxprop. The prop was already on the boat and it works fine, solves the problem of the prop turning, which always worried me on my last boat. Only issues I had was when I installed a new engine we had to play with pitch to get the engine revs / boat speed working properly. This was pretty easy to adjust whilst in the water, did it in 5 minutes. Only other problem is occasionally the props get stuck in place and do not feather when you switch the engine off and go back to sailing (you can hear the shaft turning). Its easy to fix, you slow the boat and place the engine in reverse and it fixes the problem. (Probably barnacles or seaweed catching).

They are expensive, however would definitely recommend if your budget stretches that far. Plus it resolves the issue of the prop constantly turning.

Ilenart


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## Jiminri (Aug 26, 2012)

I put a 2-blade Maxprop on my previous boat and was very happy with it. Power in reverse was great and there were never any problems with the blades opening/closing. I did not have it long enough to comment on the longevity. The company was very responsive during and right after the sale. I expect that would continue if the prop ever needed service.

My current boat came with a Flexofold. Nice, but has almost no prop walk. My previous boat with the Maxprop had some prop walk, and I miss not having it.

Yachting Magazine had a review of various props which you might find interesting. (As with any review, I'd take it with a grain of salt and an understanding this is just one data point.)

http://www.flexofold.com/upload_dir/docs/Test_YachtingMonthly_low.pdf


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## Minnewaska (Feb 21, 2010)

Our Max Prop is now ten years old and has performed like a champ. As mentioned, it feathers (twists parallel to the direction of the boat to reduce drag) when not being turned by the motor. If it doesn't do it on its own, after you shut down and are moving under sail, just briefly put the transmission in reverse and then back to neutral. Folding props, by comparison, have blades that lay down to reduce drag. That seems unnatural and more complex to me, although, that's not a very scientific argument. 

Mine has held up with no wobbling in the blades. I did hit something submerged a few years back and put a good whack in the leading edge of one blade. I didn't even know it until I hauled for the season. I believe that some systems would have torn the blade off or broken the feathering/folding prop. 

I took the unit off the shaft and mailed it back to PYI. They repaired it, cleaned it all up, rebalanced the entire unit and sent it back looking brand new for a few hundred dollars. Service was excellent! When removing from the shaft, the heavy duty build quality was very noticeable.

Finally, older models have two internal settings to get the pitch correct. It's very important that you are able to reach, but not exceed, your engines max rpm at wide open throttle under load, which is a function of prop pitch. Amazing how many are set incorrectly (on all makes and models of props), and owners can't figure out why they have engine trouble. In rare cases, you find you need to readjust by one notch upon initial assembly, which would require hauling. Maybe there is a diver than has the guts to do it under water, but there are several parts. Once right, you never touch it again, other than to grease every two years (I do so each winter)

Newer models can have their pitch adjusted from the outside, but once you get it right, you're unlikely to ever need to touch it again.


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## chucklesR (Sep 17, 2007)

My PO put on mine, one year's experience with it. 
I love it, no prop walk at all, which has good and bad sides. Good is that it is *consistent* and you can back both to port and starboard equally. Bad is you can't *use* prop walk to help you. 
It does have more power in reverse, never a bad thing to have.


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## Minnewaska (Feb 21, 2010)

Oh yea. We back into our pier side slip, down a fairway and "parallel park" between two other boats. Reverse performance is terrific. Once I get her moving in reverse, I just pull the throttle back to idle and she creeps along nicely. No need to muscle the prop in reverse.


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## capecodda (Oct 6, 2009)

Have had it on my last 2 boats, including current. As pointed out by others, it has as we say in Boston a "wicked good reverse." 

At least on my boat, it hasn't taken away the walk. We have a skeg hung rudder.

There is definitely more to go wrong, but in 15 years of experience on 2 boats, we haven't had any problems.


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## jzk (Feb 25, 2008)

We have a max prop, and it works just fine. But I wish I had a flexofold folding.

A feathering prop has no "twist". And, unless your prop shaft is level, then there will be drag from the downward angle. The flexofold is twisted like a more efficient propeller. And, you can't beat folding props for low drag. I hear no problems in reverse either.

On a sailboat, motoring efficiency is critical. The flexofold is pretty hard to beat in this regard.


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## blt2ski (May 5, 2005)

If one is having issues getting a max to fold per say, one must be over 3 knots or so when you shut the motor off, or the ability to sail at over 3 knots. putting the gear **** is reverse after shutting off will also help it get into folded mode!

A gain of .75-1 knot of boat speed while sailing is common wording for those that went from fixed to a max, or any folder/feathering prop frankly. A max prop is heavy vs other styles, and seems to use a bit more fuel while motoring because of this. But my MP thanks to previous owner also, has all the attributes mentioned by others.

Marty


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## Shockwave (Feb 4, 2014)

We have a 3 blade Classic, it's been very good and reliable for the past 13 years. We sent it in once to be refurbished, PYI is awesome, the prop came back looking like new and perfectly balanced. Good forward, good reverse, hard to beat............


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## MedSailor (Mar 30, 2008)

Sounds like a pretty good consensus that they are awesome. Great news! Even better since the previous owner foots the bill.  

The greasing issue sounds like the only one I might have a problem with. I've been very lucky with my bottom paint up in our area and typically only haul every 4-5 years or so. Can grease be added while in the water? Can the prop be taken off by a diver like a regular prop in order to grease it?

MedSailor


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## Minnewaska (Feb 21, 2010)

MedSailor said:


> .....Can grease be added while in the water?.....


Yes, I believe it can.


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## RichH (Jul 10, 2000)

MedSailor said:


> Can grease be added while in the water?


Most Max-Props have 'set screw' ports for applying grease. To do this while underwater, obtain 2 MONEL (and with MONEL internal spring) 'zerk fittings' (grease fittings) of the exact same (metric) thread profile, etc. and permanently replace the 'set screws' with the zerks. When needing to re-grease the prop with zerk fittings already installed ... jump overboard with a small grease gun in one hand, etc. ---- a 15 second job per zerk fitting .... and no tools required other than the grease gun.

You'll probably need to replace the 'zerks' every 5 years.


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## MedSailor (Mar 30, 2008)

RichH said:


> Most Max-Props have 'set screw' ports for applying grease. To do this while underwater, obtain 2 MONEL (and with MONEL internal spring) 'zerk fittings' (grease fittings) of the exact same (metric) thread profile, etc. and permanently replace the 'set screws' with the zerks. When needing to re-grease the prop with zerk fittings already installed ... jump overboard with a small grease gun in one hand, etc. ---- a 15 second job per zerk fitting .... and no tools required other than the grease gun.
> 
> You'll probably need to replace the 'zerks' every 5 years.


This makes me happy. 

MedSailor


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## Minnewaska (Feb 21, 2010)

I'm not sure I would leave the zerc fittings installed. They go to some length to be sure the props are balanced. Maybe its as inconsequential as a single barnacle. However, they may also be broken off, which would seem bad. I don't think it would be a big deal for a diver to do this correctly once every other year.


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## Fstbttms (Feb 25, 2003)

A few notes:

There is no maintenance task that the Max Prop needs that cannot be done underwater and this includes installation/removal, pitch adjustments and lubrication. PYI can recommend a diver in your area to do any of these things.

Only the very oldest Max Prop models do not have lubrication ports. I do not recommend leaving zerk fittings in these ports permanently. If either of them were to back out or be broken, you could find your prop in a world of hurt. You only have to lubricate every couple of years (and most Max Props probably don't get it even that often), so it's not a big deal to back out the set screws and run the zerk fittings in when doing this.

There are many Max Prop models and some have external pitch adjustment features and some do not. Regardless of model or age, you absolutely do not have to haul your boat to have the pitch changed.


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## MarkSF (Feb 21, 2011)

I don't know what I'd do without my prop walk, it's a great aid to maneuvering if you use it to your advantage.


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## RichH (Jul 10, 2000)

Minnewaska said:


> I'm not sure I would leave the zerc fittings installed. They go to some length to be sure the props are balanced. Maybe its as inconsequential as a single barnacle. However, they may also be broken off, which would seem bad. I don't think it would be a big deal for a diver to do this correctly once every other year.


2 zerc fittings of minimum mass applied essentially to quite near the center of rotation and center of rotational mass isnt going to make any difference to the 'balance' of such a prop, especially when such a prop is rotating at much less than the 'natural frequency' of the prop. 
If this were a high speed prop rotating at several thousand rpm .... maybe. As it is, the bullet zincs applied to such props would need to also be 'dynamically balanced at high speed' .... and that we know isnt so.


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## Minnewaska (Feb 21, 2010)

RichH said:


> 2 zerc fittings of minimum mass applied essentially to quite near the center of rotation and center of rotational mass isnt going to make any difference to the 'balance' of such a prop, especially when such a prop is rotating at much less than the 'natural frequency' of the prop.
> If this were a high speed prop rotating at several thousand rpm .... maybe. As it is, the bullet zincs applied to such props would need to also be 'dynamically balanced at high speed' .... and that we know isnt so.


I'm sure you're right. However, wrap a line around your prop and you'll likely break the fitting off.


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## killarney_sailor (May 4, 2006)

MarkSF said:


> I don't know what I'd do without my prop walk, it's a great aid to maneuvering if you use it to your advantage.


I found on my Niagara 35 with a Max-Prop that I did not have prop walk in most conditions. If I wanted to goose the stern sideways I could by giving a hard burst of throttle. Seemed like the best of both worlds.

Current boat has a fixed 3 blade, but it would have been nice to have a Max-Prop but I just could not justify the expense even though it would have speeded up passages. The cost of the rope would pay for quite a few months of cruising.


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## jfdubu (Jul 18, 2002)

Med, I've had three different props on my boat(s). My J28 came with a martec folder that after 7 years I could not stand any longer. I replaced that with a flexofold two blade folder. Hugh upgrade. solide performance in forward and reverse. never had a problem with the blades not opening The blades are geared together so if one opens( closes) they both open/close. Unlike the martec where one blade can fall open if the shaft isn't aligned just right.
I now have a max prop feathering 2 blade. I've only had this boat for 1/4 season, so far so good. My only concern is the feathering is more likely to pickup and catch crab pot lines where the folder would shed them better.

Know the difference between the folder and featherer. Both reduce drag significantly. The flexofold was not sensitive to shaft placement the max prop is. With the max prop having the prop aligned vertical yields the least drag.

My 2 cents


John


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## MedSailor (Mar 30, 2008)

jfdubu said:


> Med, I've had three different props on my boat(s). My J28 came with a martec folder that after 7 years I could not stand any longer. I replaced that with a flexofold two blade folder. Hugh upgrade. solide performance in forward and reverse. never had a problem with the blades not opening The blades are geared together so if one opens( closes) they both open/close. Unlike the martec where one blade can fall open if the shaft isn't aligned just right.
> I now have a max prop feathering 2 blade. I've only had this boat for 1/4 season, so far so good. My only concern is the feathering is more likely to pickup and catch crab pot lines where the folder would shed them better.
> 
> Know the difference between the folder and featherer. Both reduce drag significantly. The flexofold was not sensitive to shaft placement the max prop is. With the max prop having the prop aligned vertical yields the least drag.
> ...


Great points about alignment angle reducing drag and the feathering ones being more likely to pick up lines.

So, with those differences in mind, why did you switch from a folder to a feathering one?

MedSailor


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## bobperry (Apr 29, 2011)

The Max Prop is a "FEATHERING prop" and not a "folding prop". Big difference.
With a folding prop the blades do not open 100% in reverse. With a feathering prop the blades are 100% open and have the added benefit of being symmetrical blades so they are as efficient in reverse as they are in forward.

I have done a lot of prop testing and I have found the Max prop to be the best. Granted there are some props that were not available at the time I did my serious testing.
We have the new four blade Max Prop on FRANCIS and it's as close as you can come to having brakes on a boat.


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## Minnewaska (Feb 21, 2010)

If I follow, some are adding that a feathered prop on an angled prop shaft is going to expose some of the flat feathered blade to the slip stream, although, less so with a folder.

Assuming that is technically true, it has to be a distinction without practical difference. I bet you would measure the speed impact in hundredths of a knot.


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## bobperry (Apr 29, 2011)

Minn:
I have no idea what they are talking about. The blades are feathered so changing shaft angle changes only the frontal area of the feathered prop. More angle to the shaft means less frontal area.


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## Alex W (Nov 1, 2012)

jfdubu said:


> With the max prop having the prop aligned vertical yields the least drag.


I think most cruising boats will have a 3 or 4 blade Max-Prop, and then orientation while feathered has little effect. Even on a 2-blade Max-Prop I'd be curious to see how reliably the effect could be measured.

I love it when I hear the drivetrain rumbling below and realize that I forgot to let the prop feather. I put the transmission into reverse for a few seconds, the boat picks up .6 or .7 knots (sometimes even more), and everything gets quieter. It's a beautiful thing.


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## bobperry (Apr 29, 2011)

Sorry:
My comment on shaft angle was based on the 2 blade Max Prop. If I were buying a Max Pop today for my cruising boat I'd buy the 2 blade. In my testing there was very little difference in the performance of the 3 blade over the 2.

I do not think you will find many used cruising boat coming with 4 blade Max Props. It's a pretty new prop. And pricey.


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## jfdubu (Jul 18, 2002)

Med, My "new to me" boat came with the maxprop. If I ever have to change it I will likely go back to the flexofold.

For the record the flexofold does open 100% in reverse and one can hear the thud when it does. I was able to stop forward motion and start reverse motion from 4 knots forward in 4 boat lengths. Not as good as a feathering but way better than the martec where reverse was only a suggestion.

Regarding the angle, It's not so insignificant. My shaft is on a 15° angle. If the prop is horizontal and the blade is about 6" wide and 12" long it's like dragging a 1.5"x 12" board. If it's vertical, the drag is only the exposed thickness of the blade and one of the blades is right behind the drive strut. To most sailors, no big deal. But if you race and think there's a difference between wet sanding the bottom and not, that's a lot of drag.


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## Minnewaska (Feb 21, 2010)

Alex W said:


> ......I love it when I hear the drivetrain rumbling below and realize that I forgot to let the prop feather. I put the transmission into reverse for a few seconds, the boat picks up .6 or .7 knots (sometimes even more), and everything gets quieter. It's a beautiful thing.


Funny, I never hear the turning prop from the helm. You have to be further forward in the cockpit. Often, someone will say to me "what's that noise" and I immediately know. Same procedure and it stops and suddenly I'm not working so hard on boat speed.


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## bobperry (Apr 29, 2011)

jf:
You have a folding prop. The Max prop feathers. The shaft angle withgin reason, makes very little difference as I said. If you race you'd have the 2 blade obviously and the difference is almost non existant. If you are a serious racer you most probably have a sai drive anyway so your shaft angle is very close to horizontal.


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## Alex W (Nov 1, 2012)

Minnewaska said:


> Funny, I never hear the turning prop from the helm. You have to be further forward in the cockpit. Often, someone will say to me "what's that noise" and I immediately know. Same procedure and it stops and suddenly I'm not working so hard on boat speed.


Me hearing it and you not hearing it might have something to do with your boat being twice as long as mine . The prop shaft is just below the helm on my boat.


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## jfdubu (Jul 18, 2002)

Bob, 
I have a feathering maxprop. I had a flexofold folder which replaced my martec folder on my old boat. Shaft angle and orientation has no effect on the flexofold as both blades fold as one. On the martec one blade would "fall down" depending on orientation of the shaft, not the angle.
The steeper the shaft angle the more exposed area of a feathered feathering prop in the horizontal orientation. Yes, with a saildrive it makes almost no difference as the prop shaft is horizontal. My boat is 20yrs old with shaft
While I don't consider myself a "serious" racer, I don't wet sand the bottom, I do look for every bit of speed I can get.


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## bobperry (Apr 29, 2011)

jf:
Exactly that's why a serious racer would feather his 2 blade Max Prop in the vertical position. That way shaft angle means little and one blade is hidden behind the strut.

How did you like the Flexofold? I hear good things. No experience myself.


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