Max Prop or Not?

[a64pilot]

Worth it for 38' Island Packet? Or save your money it just doesn't make enough difference?
Current prop a 17' three blade at 16' pitch, should be a 12' pitch so I need a new prop to be correct anyway, plus would like to have a spare just in case.

Was thinking a three blade "Easy", or should I go with four blades? Airplane props lose efficiency with more blades, but gain in lower vibration levels, assume same for sailboat props?

I've searched and not found much except for advice on how to grease etc.
If I go with a Max, I definitely want an "Easy" to be able to dial in prop pitch without hassle.

[delmarrey]

I love my 3 blade Max-Prop. The only advantage to the 'easy' is if you want to experiment a lot. Once the blades are set to the right pitch, it'll never need to be adjusted again. But 17' w/12' pitch sounds about right, depending on the torque of your engine. It all comes down to the money.

One suggestion though, if you do go Max-Prop, shift slowly between forward and reverse, or with a slight hesitation. It prevents the dog ears from mushrooming, causing a reversing problem in its later hours of operation.

[Dockhead]

A proper feathering prop pays huge dividends in sailing efficiency. Yes, it's worth it.

The Max Prop has a fantastic reputation, and is standard fit on Oysters.

Max Prop have a new variable pitch prop called the Eco Wind. I don't know anything about it, but worth checking out, since MaxProp = great maker and Variable Pitch = extremely useful function. The regular Max Prop is fixed pitch, adjustable in the water.

The other variable pitch prop available is the Autoprop. It's very expensive, but very good. I have had Autoprops on all m boats since the '90's.

That could be a good choice for you, too. Their main disadvantage is that they droop a blade while sailing, which means they have higher drag than all other folding/feathering props. That means they are no good for racing boats or very high performance sailboats. But they are still an order of magnitude better than a fixed prop what concerns drag while feathered, and on a boat with an inefficient underbody like an IP, I doubt if you would feel the difference. What's good about them is that the variable pitch means you always have the right pitch for conditions -- coarser in easy conditions and finer when you have to bash into seas and wind -- this is really great. And best of all maybe motorsailing -- they will pitch right up while motorsailing so that you can throttle right back -- makes for an exquisite motorsailing experience. Not just because you save fuel, but because it just feels better with the engine throttled right back, running quietly.

I think this function is also better for your engine, as it helps to keep the engine properly loaded.

So if I were you, I would look mostly at the Eco Wind and the Autoprop.

The third type of variable pitch prop is clearly the best of all -- the manually adjustable Hundestad. But it's not made in a small enough size for your boat, I think.

[a64pilot]

Currently I pause of at least a sec or two between fwd and reverse, I just got it in my mind that you need to let the prop stop before trying to make it go the other direction.

I've called PYI about the Ecowind, and it's not applicable in this instance. It works by having a spring drive the prop into coarse pitch, but hydrodynamic forces drive it to fine pitch. Long story short it's not a good match for the high RPM Yanmars that don't have a lot of torque at low RPM, in order to keep from bogging the engine too much at low RPM, the spring has to be so weak as to be ineffectual. Good prop for a bigger, heavier boat with an in-line JD six cylinder or other high torque, low RPM motor, but unfortunately not for me.

Right now I'm pitched so all I can get is 2500 RPM, this on a motor that is supposed to turn 3600, but believe it or not, no black smoke. Still I only run her at 2,000 RPM which is about 6.5 kts with a clean bottom, it works really well for motorsailing, just gotta be lugging the motor and that can't be good, plus if I get in a spot where I need the HP, I won't have it.

I'll look into the Autoprop as I don't know much about it, where did you get yours?

[colemj]

Originally Posted by Dockhead

The other variable pitch prop available is the Autoprop. It's very expensive, but very good. I have had Autoprops on all m boats since the '90's.

That could be a good choice for you, too. Their main disadvantage is that they droop a blade while sailing, which means they have higher drag than all other folding/feathering props.

Those are feathering props. How do they droop a blade? Do you mean one blade unfeathers? Why would that happen?

Mark

[carstenb]

I switched from a 3 balded volvo folding prop to a Max-prop last year.

Unbelievable difference. We now can stop the boat and have full power in reverse. Our engine is a Yanmar 4JHE 55 horse. At 2000 rpm our boat moves right along at 61/2 to 7 knots.

Good acceleration etc.

Only issue we have had is the prop not feathering by itself when I stop the engine. I've now found out that if I stop the engine while in gear and going at 3+ knots it will feather (this was a recommendation from Max-prop).

Other wise, after you stop the engine, drop it into reverse and back to neutral really quickly and the prop will feather.

[TacomaSailor]

We've had an 18" Maxprop on our Caliber 40 since spring 1995 (Yanmar 4JH2E 50HP). It is has consistently been shown to add 0.3 to 0.6 knots of sailing speed whenever we test it.

- stop boat
- turn off motor (thus ensuring Maxprop does not feather)
- start sailing and carefully monitor VMG, SOG, CMG
- try the other tack

- slow the boat down
- motor for a minute at more than 4-knots
- put engine in Neutral
- put engine in Reverse (while still above 3.5 knots thus ensuring Maxprop feathers)
- start sailing again
- carefully monitor VMG, SOG, CMG
- try the other tack

- compare non-feathered and feathered VMG, SOG, COG

We had PYI rebuild the prop to factory tolerance at 2,000 engine hours (8-years of cruising). When they received the prop for rebuild they said everything was still within
original factory specifications.

We had the prop inspected again in Nov 2012 (2,840 hours and 18 years of use) and it was still within original tolerances.

Once you learn to manage the prop walk in Reverse it is a real aid to docking and maneuvering.

I highly recommend the Maxprop!

[jstevens]

+1 on the value of a feathering prop. I've had a 3-blade MaxProp Classic for over 12 years. It was a major improvement over the fixed 3-blade that came with the boat, especially when maneuvering to dock. That is the only feathering prop with which I have personal experience, but I know others who are very satisfied with other brands (e.g., Autoprop).
I'm not sure of the value of the "Easy" MaxProp. As the previous poster noted, setting the pitch is normally not a recurring event. If you hire a mechanic to help/do the installation he will undoubtedly want to make the adjustments with the boat in the slings. Usually it will take a couple of short hauls between sea trials to get the optimal pitch.
Both versions can be lubricated in the water, but it is a lot easier on land.

John

[fstbttms]

Originally Posted by jstevens

Usually it will take a couple of short hauls between sea trials to get the optimal pitch.
Both versions can be lubricated in the water, but it is a lot easier on land.

Any version of Max Prop can be installed, removed, adjusted and lubricated underwater. No reason to haul for any of this work, regardless of model.

[a64pilot]

Anyone bought their Max Prop at P2 Marine or PY Yacht? I ask as they are about 10% less than PYI.
Think PYI will price match?

Who is the US distributor for Autoprop?
I'm trying unsuccessfully to find out how the Autoprop works as far as self adjusting pitch is concerned.

I've found one review from an owner of an Oyster that is well pleased and a couple of comments about the props spitting blades?

[Kenomac]

We've been very pleased with the Maxprop performance on our Oyster and even had one on our previous Hunter 450. The only issue, is that we need to pause between forward and reverse, then after the gear is engaged, give the the throttle a quick burst before going slow in the new direction. Otherwise the prop bangs while trying to shift to the new position under a light load. Maxprop offers plenty of reverse power.

[gjordan]

A64pilot, I am going to give a different slant on changing props. The big issue (imo) is if in the next ???number of years, you are going to be coastal cruising, or is crossing oceans in the near future? Any good prop shop could re-pitch or shorten your prop, or a little of both, to get you into the proper RPM range. Most coastal cruisers tend to use their motor any time the wind goes light, so the real beauty of the folding, or feathering prop (light air sailing) isnt being used to its best advantage. Passage making can be improved considerably with a folder, or feathering prop, especially in light air. I tend to compare fixed versus feathering much like I do auto-pilot vs windvane. Coastal cruising, put your money into an auto-pilot, away from land (and repair facilities) for weeks at a time; put your money into a windvane. Same sort of thing with props. Like almost all things on CF, I am just giving an opinion. Best of luck. ______Grant.

[Dockhead]

Originally Posted by colemj

Those are feathering props. How do they droop a blade? Do you mean one blade unfeathers? Why would that happen?

Mark

The blades are not geared and there are no springs. They are pitched purely by hydrodynamic forces. Advantage of that is extremely simplicity. Disadvantage is that one blade will have gravity trying to force it down into the water stream.

As a result, the objective measured drag is higher than any other feathering prop, an inherent drawback of the Autoprop.

P.S. That's why you don't seem them on race boats, nor on cats.

[Freedom45]

I just bought a new 18" 3 blade Max-prop to replace the same, the old had corrosion and was a bit neglected, the rebuild would have been 2K so it made sense to me to buy a new one. I was on the hard in Ensenada and thought about putting my old fixed prop on and save the 3K...no way would I be happy with the fixed prop.
I love the prop, pick up half a knot when feathered, boat backs up nicely, very little prop walk. Worth the price to me. I recommend them.

Chuck

[Dockhead]

Originally Posted by a64pilot

Currently I pause of at least a sec or two between fwd and reverse, I just got it in my mind that you need to let the prop stop before trying to make it go the other direction.

I've called PYI about the Ecowind, and it's not applicable in this instance. It works by having a spring drive the prop into coarse pitch, but hydrodynamic forces drive it to fine pitch. Long story short it's not a good match for the high RPM Yanmars that don't have a lot of torque at low RPM, in order to keep from bogging the engine too much at low RPM, the spring has to be so weak as to be ineffectual. Good prop for a bigger, heavier boat with an in-line JD six cylinder or other high torque, low RPM motor, but unfortunately not for me.

Right now I'm pitched so all I can get is 2500 RPM, this on a motor that is supposed to turn 3600, but believe it or not, no black smoke. Still I only run her at 2,000 RPM which is about 6.5 kts with a clean bottom, it works really well for motorsailing, just gotta be lugging the motor and that can't be good, plus if I get in a spot where I need the HP, I won't have it.

I'll look into the Autoprop as I don't know much about it, where did you get yours?

You do not want to be lugging that motor. Proper pitch is essential, or you will screw up the motor and/or waste fuel, etc. I would for sure ditch that fixed prop, which is like dragging a bucket behind you when you sail.

The Autoprop works fine with the Yanmar. I have a 100 horsepower 4JH3HTE which revs up to 4000RPM and it works great.

My prop was original fit to my Moody, supplied by the factory. So I can't tell you where you can get it, but I'm sure the factory can: Autoprop: Propellers

It's made in the UK by Brunton, a company which makes big ship propellers.