Replacing my Max Prop questions

[Mike H.]

Has anyone replaced their Max Prop with a fixed prop? Our 1989 Beneteau First 35s5 has a Max Prop. We bought the boat in June of 2019. We hauled it out for the survey and I checked and photoed the prop. It functions properly, but it is really pitted. I don't know if it was original to the boat 31 years ago, or if was an upgrade. I'm not happy with the performance of this prop. Especially in reverse. It takes a lot of RPM to get it going in reverse and it has nor prop walk, (which I am used to and take advantage of). In close quarters, it is sketchy with this prop. I don't care about the extra speed that it provides. We're not racers. We sail in the SF Bay Area where the currents are strong and I like the extra power when I need it.

So my questions are:

1- Is it likely that the end of the shaft was cut down to accept this prop? I saw installation videos for new Max Props AND THEY CUT THE END OF THE SHAFT OFF!
2- Will I have to source a new prop nut to hold on a new fixed prop?
3- A new fixed prop is in the $ 900. range plus another $ 90. for the bushing from 25mm to 1 1/8". It would take PYI two weeks to refurbish the Max Prop, the cost would be $ 400. to $ 1,000. plus another $ 400. in lay days. Is it worth it to refurbish a 30 year old prop at that rate. No. I just answered my own question.
4- Main question. Is this an easy swap, or should I just work with the old Max Prop?

 

[jssailem]

Not sure of your priorities. If racing, then a folding prop will give you optimal racing performance.
If cruising and you have tidal currents with windless weather conditions then look at the Campbell Sailor prop from West by North.

I am happy with my CS prop.

 

[dlochner]

I have a Max Prop and I'm pretty happy with it. Before going further on the decision to replace it, take a scotchbrite pad and clean it up. It is difficult to see its condition.

There should be an anode on the aft end of the prop hub. The cone on the aft end of your prop does not look right, it is far too pointy. The prop should have this in addition to the shaft anodes, which look like they need replacing.

Rotate the blades, they should turn smoothly, if not, they need to be lubricated. Check with PYI, they have instructions on how to grease the hub so the blades rotate smoothly. It is a 5 minute job if you don't drop the set screws in the grass. This may be part of the problem you have with reverse.

I find the Max prop to have a lot of prop walk in reverse, sometimes too much. All folding or feathering props need a burst of energy to get the blades to open up or change direction, either going from forward to reverse or vice-versa. The water flow over the blades causes them to feather, that water flow has to be countered before the blades rotate out.

Changing to a fixed 3 blade prop will cost you between a half to a full knot of boat speed in light to moderate conditions.

 

[capta]

MaxProp will recondition your prop for a fraction of what it would cost you to replace it. It sounds to me as though you have the pitch set incorrectly on your MaxProp. Have you considered that if you replace the MaxProp with a fixed prop you will need to install some sort of shaft brake, unless you want to listen to the prop spin all the time you when you are sailing.
I've sailed the Bay extensively and if I'd had the possibility of getting a Maxprop, it sure would have been a help on those high current, light wind days. No need to be a racer to enjoy better performance on your boat.

 

[Sandy Stone]

That is an older model MaxProp, like mine, which does not have an anode. It does look to be in rough shape, indicating that the shaft anodes were not adequately maintained. I don't understand the comment about poor performance in reverse, and no prop walk. My prop has crazy reverse thrust, better that a fixed prop, and prop walk about the same as a fixed.
If you clean up the prop, you may be able to get some more use out of it. For sure follow the advice above, disassemble it, grease it, and consider changing the pitch. There is no way you should have to rev the engine to get reverse. One thing - it will be a LOT easier to reassemble the prop with two people. A lot of greasy little parts that all have to line up at the same time.

 

[dmax]

If you decide to go the fixed prop route, look at Campbell Sailor props, more efficient than other fixed props.

 

[FastOlson]

One little caveat. The enthusiasm for the C. Sailor Props is fine and most owners are making well-intentioned comments. Remember, tho. that what Campbell has done is to make their narrow profile blade seem like something they invented.
Nothing wrong with the idea, but other prop builders have always done the same thing.
They do imply that their tip shape is different enough to make it superior - perhaps or perhaps it's not that significant. (?)
When it comes to drag, you have to look at the raw amount of blade area crossways to the water flow. That is the resistance that you have to overcome when sailing.
In about 25 years with our current boat we have used: the stock fixed two blade, a feathering two blade for a decade, and a narrow-3-blade Michigan "sailor" prop for another decade.
Most drag is about a tie between the old standard-profile two blade and our current narrow-blade three-blade.
Either can subtract 3/4 to 1 knot of sailing speed. The three blade IS noticeably better motoring agains surface chop and wind.
OTOH, the featherer had better power and control in reverse.

As some old salt once opined : "everything's a compromise".

So choose among the pluses and minuses but just remember that designing props is a very old math/engineering discipline, and when someone implies that they have tricked the water flow.... the sea is likely not impressed.

Finally, the folks with the "campbell sailor props" all seem pretty happy, so, hype aside, it functions as well as any other competing blade design.

 

[dlochner]

The three blade IS noticeably better motoring agains surface chop and wind.
OTOH, the featherer had better power and control in reverse.

This is due to the shape of the blade. A feathering prop, like the Max Prop, has a blade that is practically flat to minimize drag when feathered and sailing. A folding prop, like a Martec, Gori, or Flexo Fold acts more like a fixed blade prop because the blades have some shape to them.

The folding props are better in forward than feathering prop and the feathering props are better in reverse than either the fixed or folding props because the large flat blades are more efficient than curved blades.

I went from a 30' boat with a folding Martec to a 36' boat with a Max Prop, it took some time to learn the handling characteristics. I tried to only dock the boat when no-one was watching. It wasn't always pretty until I learned the boat's handling characteristics.

 

[jssailem]

it took some time to learn the handling characteristics

This skill development is learned by doing it. As Nike suggest..... Just Do It!

 

[Mike H.]

This is due to the shape of the blade. A feathering prop, like the Max Prop, has a blade that is practically flat to minimize drag when feathered and sailing. A folding prop, like a Martec, Gori, or Flexo Fold acts more like a fixed blade prop because the blades have some shape to them.

The folding props are better in forward than feathering prop and the feathering props are better in reverse than either the fixed or folding props because the large flat blades are more efficient than curved blades.

I went from a 30' boat with a folding Martec to a 36' boat with a Max Prop, it took some time to learn the handling characteristics. I tried to only dock the boat when no-one was watching. It wasn't always pretty until I learned the boat's handling characteristics.

Yeah, getting to know the handling characteristics is a challenge around the docks. Gotten into some pretty sticky situations.

 

[fstbttms]

So my questions are:

1- Is it likely that the end of the shaft was cut down to accept this prop? I saw installation videos for new Max Props AND THEY CUT THE END OF THE SHAFT OFF!

Yes, your SAE shaft had a part of the threaded end cut off to accept the Max Prop. This is not the case with metric shafts however.

...plus another $ 90. for the bushing from 25mm to 1 1/8"

Are you saying your Hunter has a 25mm shaft? That would be extremely unusual.

2- Will I have to source a new prop nut to hold on a new fixed prop?

Yes.

Is it worth it to refurbish a 30 year old prop at that rate. No. I just answered my own question.

You do not need to haul to swap out any prop, Max Prop included. Of course, you're talking about a new shaft as well. That can also be done while the boat is in the water, but that's not a job most divers are prepared to tackle.

 

[Sandy Stone]

Note OP stated boat is a Beneteau First 35s5. Certainly a 25mm shaft from the factory.

 

[fstbttms]

Note OP stated boat is a Beneteau First 35s5. Certainly a 25mm shaft from the factory.

Not sure why I thought he had a Hunter.