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Old 03-06-2014, 10:54   #16
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Re: Maxprop - Issues with Feathering

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Originally Posted by poiu View Post
The process of feathering isn't like that. The prop feathers in the last few engine revolutions as the engine slows to a standstill when going forwards not after stopping the shaft by putting it in reverse as you describe. Once the engine is stopped, the shaft is also stopped. If you go into neutral it may start rotating again due to hydrodynamic imbalance or its inertia. That is the scenario the manual is referring to when it says you can put it in reverse if the shaft is spinning. (And why I said it was misleading-probably a bad translation from the Italian). As I mentioned in my previous post, you can just as well put the transmission in forward gear to stop that movement.
Well... with the Max Prop it is like that sometimes... that's what works and it's pretty common knowledge... just sayin'. Had 4 boats with Max Props. They all required either stopping in gear or going in and out at times. ... Not always.
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Old 03-06-2014, 11:20   #17
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Re: Maxprop - Issues with Feathering

I own a big max prop for the last 8 years, you have a small problem there at the prop, in fact you dont need to put the gear in backwards or forward, first of all excesive greasing slow the blades free movement, some grease is fine ,to much nop,,, i wonder if in your last haul out you check the blades all the way forward and reverse? no hard spots or binding?? if yes, fine sandpaper and oil do the trick at the internal cone gear, i never see my prop spining in neutral , even doing 7 knts under sail or surfing a wave , and another isue could be your prop shaft is not aligned with the true centerline of the hull , some builders shift the shaft one side or the other to allow remove the shaft with the rudder in place but disturbing the natural flow in the prop... hope this help...
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Old 03-06-2014, 11:24   #18
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Re: Maxprop - Issues with Feathering

I forgot to mention if your trany is hydraulic or not, borg warner style,??
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Old 03-06-2014, 12:10   #19
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Re: Maxprop - Issues with Feathering

I've got a three bladed Maxprop and a PRM 150 hydraulic gearbox. To get it to feather I have to stop the boat, or slow her down to a knot or two, engage neutral, then the prop feathers on its own. If we're sailng too fast nothing happens and it'll never feather.
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Old 03-06-2014, 12:33   #20
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Re: Maxprop - Issues with Feathering

Once the shaft is stopped, the Maxprop will feather and stay feathered. However, if the shaft is allowed to freewheel, the prop will remain engaged.

If you have a transmission like a Hurth or Twin Disc, the simplest way to stop the shaft is to stop the engine and THEN put the transmission in reverse. Putting the trannie neutral obviously does not work, and leaving the trannie in forward does not work, as these transmissions have a one-way ratchet effect that allows the prop to spin faster than the transmission.

If you have a hydraulic transmission, its a bit trickier, as there may not be enough friction in the transmission to stop the propshaft. A friend told me what works on his boat, but I forget what it was.
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Old 03-06-2014, 23:55   #21
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Re: Maxprop - Issues with Feathering

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Originally Posted by neilpride View Post
I own a big max prop for the last 8 years, you have a small problem there at the prop, in fact you dont need to put the gear in backwards or forward, first of all excesive greasing slow the blades free movement, some grease is fine ,to much nop,,, i wonder if in your last haul out you check the blades all the way forward and reverse? no hard spots or binding?? if yes, fine sandpaper and oil do the trick at the internal cone gear, i never see my prop spining in neutral , even doing 7 knts under sail or surfing a wave , and another isue could be your prop shaft is not aligned with the true centerline of the hull , some builders shift the shaft one side or the other to allow remove the shaft with the rudder in place but disturbing the natural flow in the prop... hope this help...
I have checked the prop for free movement both forwards and backwards. I can feather it with a bit of light pressure with my finger. I did grease it again (according tothe manual - grease until some comes out of the sides - too much? I don't know, I followed instructions.

One issue with putting t in reverse is that if I do, the tranny virtually locks up. I realy do need to slam the lever to get it back into neutral.

I haven't tried stopping the engine with it still in gear. I'll try that this weekend.
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Old 12-06-2014, 15:51   #22
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Re: Maxprop - Issues with Feathering

Quote:
Originally Posted by poiu View Post
The process of feathering isn't like that. The prop feathers in the last few engine revolutions as the engine slows to a standstill when going forwards not after stopping the shaft by putting it in reverse as you describe. Once the engine is stopped, the shaft is also stopped. If you go into neutral it may start rotating again due to hydrodynamic imbalance or its inertia. That is the scenario the manual is referring to when it says you can put it in reverse if the shaft is spinning. (And why I said it was misleading-probably a bad translation from the Italian). As I mentioned in my previous post, you can just as well put the transmission in forward gear to stop that movement.
Actually, the process of feathering is exactly as cal40john described it, this is completely wrong and contains even more bad advice.

On a normal installation, the shaft will usually keep rotating after the engine is taken out of gear at speed. Engaging the reverse gear causes immediate feathering and it won't restart after that, even in neutral. If the shaft is at a significant angle or the flow in the stern region really screwed up, it may move a bit, but the prop won't pitch itself again.
A hydraulic box can make stopping the shaft a lot more tricky as someone pointed out, but they are less common on yachts.

You should most definitely NOT put the transmission in forward gear while sailing, because some designs of clutches can slip and you can destroy your discs or cones doing that. Reverse locks hard and won't slip on a mechanical transmission.

Now back to the question from the OP: there is something interesting about Max-Props: if you stop the engine in reverse, the propeller will remain pitched afterwards, even with forward speed. Locking the shaft with the gearbox afterwards won't cause the prop to feather either, it only feathers if it was last pitched "forward". You can use this feature to drive a shaft alternator with a Max-Prop, you briefly drive the shaft in reverse, go back to neutral and your shaft remains engaged until you motor forward again.
This makes me think that you could have a mix up between forward-reverse in your transmission linkage and your Max-Prop assembled for the wrong rotation direction.
If you happened to be driving forward with a Max-Prop pitched in reverse, you should get exactly the strange behaviour you are describing and a Max-Prop can be assembled for LH or RH rotation.

It may sound like a long shot, but I saw once a Max-Prop installation with a gearbox that was operating the wrong way and it was a while before we got to the bottom of it, because the lever on the transmission was "forward for forward" when in fact it should have been pointing back...

Hope it might help and all the best,

Eric
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Old 13-06-2014, 01:09   #23
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Re: Maxprop - Issues with Feathering

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Originally Posted by OceanSeaSpray View Post

Now back to the question from the OP: there is something interesting about Max-Props: if you stop the engine in reverse, the propeller will remain pitched afterwards, even with forward speed. Locking the shaft with the gearbox afterwards won't cause the prop to feather either, it only feathers if it was last pitched "forward". You can use this feature to drive a shaft alternator with a Max-Prop, you briefly drive the shaft in reverse, go back to neutral and your shaft remains engaged until you motor forward again.
This makes me think that you could have a mix up between forward-reverse in your transmission linkage and your Max-Prop assembled for the wrong rotation direction.
If you happened to be driving forward with a Max-Prop pitched in reverse, you should get exactly the strange behaviour you are describing and a Max-Prop can be assembled for LH or RH rotation.

It may sound like a long shot, but I saw once a Max-Prop installation with a gearbox that was operating the wrong way and it was a while before we got to the bottom of it, because the lever on the transmission was "forward for forward" when in fact it should have been pointing back...

Hope it might help and all the best,

Eric
I suppose this could be true, although the prop was assembled by a shop that only seals in propellers - so I'm assuming they do know what they are doing. The part about my tranny cable being backwards, I don't understand.

When I put the tranny in "forward" the boat goes forward , revers works also. When I had the boat hauled a couple of weeks ago, i double checked to make sure the leading edges of the prop were correct.

Can you expain this again in language a simple guy like myself can understand?


Thank you
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Old 13-06-2014, 02:38   #24
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Re: Maxprop - Issues with Feathering

My apologies, I haven't been clear enough, but it is all a remote guess.

It is quite easy to get a Max-Prop together the wrong way, so I wouldn't assume it is fine just because a shop did it.
If your shaft was in fact turning in reverse when you ask for forward, but your prop had been assembled for this rotation, you would still go forward with the boat - this is the situation I saw once. The reduction ratios were all screwed up, because there was a difference between forward and reverse. It was a new boat, so everything was untested. If you have only replaced a fixed prop, this could be a lot less likely.

The only situation I know where Max-Props absolutely refuse to feather when the shaft is locked is when they were last pitched for reverse. So I am tempted to guess that yours is not assembled correctly and/or there is a rotation problem thrown into the mix.

Check your engine manual for the position of the gearbox control lever for forward/reverse and make sure you indeed get the expected movement when you ask for forward from the cockpit.
If this is fine, then I would take the Max-Prop to pieces again and restart with the book, because there are a great many ways of putting them together incorrectly with a wide range of surprising consequences. I wouldn't even try to guess all what could happen.

There is a way to test your Max-Prop:

When you pull backwards on the trailing (broad curved) edges of the blades of a Max-Prop pitched "forward", it tries to spin immediately and the blades feather. If you do the same from reverse pitch, nothing happens: it feels like a fixed blade prop. This you can check easily enough, stop with the engine in forward gear and dive under. If it doesn't do that, something is definitely wrong with it and you must take it apart again.
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Old 13-06-2014, 02:41   #25
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Re: Maxprop - Issues with Feathering

Doug, my curious helper, was asking about the different prop types last weekend.

I showed him fixed, folding and feathering.

Lo and behold the feathering prop we looked at had the foils mounted backwards. I din't think that was possible but for sure the trailing edge of the blades are biting when the prop is spinning in forward.

I have a MaxProp Duo. Has never failed to feather. I pack it "full" of grease. I shut the engine off in gear (saildrive) then go to neutral.

Late in a hull cleaning cycle I did hear the tranny turning - so I know what it sounds like if it doesn't feather. There was enough buildup on the prop that feathering was not an option.
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Old 13-06-2014, 03:11   #26
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Re: Maxprop - Issues with Feathering

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Originally Posted by OceanSeaSpray View Post
My apologies, I haven't been clear enough, but it is all a remote guess.

It is quite easy to get a Max-Prop together the wrong way, so I wouldn't assume it is fine just because a shop did it.
If your shaft was in fact turning in reverse when you ask for forward, but your prop had been assembled for this rotation, you would still go forward with the boat - this is the situation I saw once. The reduction ratios were all screwed up, because there was a difference between forward and reverse. It was a new boat, so everything was untested. If you have only replaced a fixed prop, this could be a lot less likely.

The only situation I know where Max-Props absolutely refuse to feather when the shaft is locked is when they were last pitched for reverse. So I am tempted to guess that yours is not assembled correctly and/or there is a rotation problem thrown into the mix.

Check your engine manual for the position of the gearbox control lever for forward/reverse and make sure you indeed get the expected movement when you ask for forward from the cockpit.
If this is fine, then I would take the Max-Prop to pieces again and restart with the book, because there are a great many ways of putting them together incorrectly with a wide range of surprising consequences. I wouldn't even try to guess all what could happen.

There is a way to test your Max-Prop:

When you pull backwards on the trailing (broad curved) edges of the blades of a Max-Prop pitched "forward", it tries to spin immediately and the blades feather. If you do the same from reverse pitch, nothing happens: it feels like a fixed blade prop. This you can check easily enough, stop with the engine in forward gear and dive under. If it doesn't do that, something is definitely wrong with it and you must take it apart again.
I did this when I had the haul out. The balde feather with just a light finger touch. When it was in a "reverse" position, it stayed locked (pushing "backwards" on it).

Perhaps I should mention that the prop replaced a volvo 3 bladed folding prop. There were no folding issues with that, so it seems unlikely that the tranny is rotating the wrong way. I replaced the prop because the volvo had an unbelievable amount of propwalk. It was almost impossible get the boat moving backwards without first turning almost sideways. Stopping power (and backing down on an anchor) were real issues.


My only issue with dropping the tranny in reverse to feather is that the tranny "locks" and I have to use an excessive amount of force to get it back into neutral
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Old 13-06-2014, 06:04   #27
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Re: Maxprop - Issues with Feathering

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Originally Posted by cal40john View Post
If mine doesn't automatically feather I put the tranny into reverse for a second and it feathers and the shaft stops turning.

I don't know if the prop works at all with the blades backwards, but according to the manual it is possible to put them on the wrong way. If so it seems to me that the blades would open up every time you would want them to feather.

page 4 figure 7:
http://www.pyiinc.com/images/pdf/max...structions.pdf
YES IT IS! On my last session on the hard, I decided to pitch up my Max, and upon re-assembly goofed up something.... Forward became reverse and vice-versa. Departure from the ways was almost a disaster! The lift operator saved my bacon(and hull) by keeping the forward strap tight, otherwise I would have crashed into the sea wall.
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Old 13-06-2014, 08:18   #28
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Re: Maxprop - Issues with Feathering

Although the Maxprop's are very finely made, I have found that a large improvement can sometimes be made in their feathering ability by carefully removing all burrs and lapping the internals with valve grinding compound.

Also, it is possible to distort the hub by over-torquing the prop nut.
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Old 14-06-2014, 03:29   #29
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Re: Maxprop - Issues with Feathering

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...

My only issue with dropping the tranny in reverse to feather is that the tranny "locks" and I have to use an excessive amount of force to get it back into neutral
So, if I read correctly, you don't have a feathering problem with the Max-Prop. It sounds like it behaves as should be expected.

I went back to your original posting and it can be read as "if you try to feather it by going into reverse with the engine, it remains locked in reverse pitch".
This would be normal behaviour as well as I was indicating earlier. This can't work with a Max-Prop.

The fact that you need a lot of force to get out of reverse after feathering the Max-Prop would point at a minor gearbox issue. If it has a cone clutch especially, it can indicate excessive internal wear. Sometimes, some machining / shimming can fix this, otherwise replace the worn parts. It gets too much travel inside basically.

It sounds a whole lot simpler suddenly. I kept thinking about it and I couldn't really make sense of it. I hope that is all it is.
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Old 14-06-2014, 03:38   #30
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Re: Maxprop - Issues with Feathering

Sorry if I misexplained. it si the tranny that locks up, requiring force. On the ohter hand, it requries no force to move the tranny out of reverse if I have been using the engine to back the boat. It just slips out like it is supposed to.
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