H41 folding/feathering propeller performance

[dakno]

Hello skippers
I have a 08 H41 purchased May of 15. We did a sea trial, completed purchase. Boat came with a fixed 18x12 prop. I ordered a Maxiprop feathering propeller and had it installed supposedly at a 12 pitch the day we left Kemah to sail to New Orleans. The boat did not seem to have the same boat speed per rpm level but I wasn't sure because I only took the boat out twice in Galveston Bay using motor for short periods only so I had no certain knowledge of performance beforehand. This week we motored to Florida( the wind was in our face) with a Beneteau 45 that has my identical engine , Yanmar 54, and weighs 5k more. I could not keep up with him. The Bene does 8k at 2200rpm, I do 6k. At 2600rpm I do 7k. At max rpm, 3200, I will do 7.5 flat out. The Bene is spanking me at much lower rpm pushing 5000 # more? We both have clean gear and bottoms. He has a sail drive and a Gori folding prop. I have a shaft. I fairly certain I have a problem. Opinions? What performance do you get with the same engine ?

 

[SG]

First, does your Hunter 41DS have a clean bottom and is the prop clean?
Secondly, where did you get the "12 pitch"?
Finally, is the MaxProp a model that allows for you to adjust the pitch while you're in the water. (Assuming a diver knows what he's doing)?

I trust that you don't have an issue with the prop in reverse; and, that there isn't some undue vibration that would indicate that the prop isn't functioning?

 

[M_Michaels]

I had a Max Prop on my Hunter 380. I was not happy with the boat speed and the feathering of that prop. I went with a new Flex-o-fold prop and was impressed with the improvements. Faster sailing, faster motoring, stops well and is not mechanically complicated.

 

[SG]

The Flexofold is a very good filing prop. It has an amazing efficiency in reverse, which is often a problem with folding props.

We have had two boats with Maxiprops over thirty years and have been very pleased with them.

 

[TFlight]

I love my flexofold prop 18x14-3R, 2007 Hunter 41DS
I sent you a PM

 

[MetricMountie]

We have a three blade Flex-O-Fold on our 95 - 40.5, the prop gives us excellent performance at all rpm's, does well folded under sail and is extremely good in reverse with very little walk and the ability to stop the boat quickly.

 

[seadaddler]

I have a few friends that have been complaining about their
Max prop and so unhappy they removed it.
I think they must not be an easy prop to setup and some very happy with some prop’s.
I also have 3 blade Flex O Fold prop and love that never have a problem and easy and one time in 10 years needed to be cleaned to perform properly and no greasing or anything just trykeep clean.
Nick

 

[Rick486]

Hello skippers
I have a 08 H41 purchased May of 15. We did a sea trial, completed purchase. Boat came with a fixed 18x12 prop. I ordered a Maxiprop feathering propeller and had it installed supposedly at a 12 pitch the day we left Kemah to sail to New Orleans. The boat did not seem to have the same boat speed per rpm level but I wasn't sure because I only took the boat out twice in Galveston Bay using motor for short periods only so I had no certain knowledge of performance beforehand. This week we motored to Florida( the wind was in our face) with a Beneteau 45 that has my identical engine , Yanmar 54, and weighs 5k more. I could not keep up with him. The Bene does 8k at 2200rpm, I do 6k. At 2600rpm I do 7k. At max rpm, 3200, I will do 7.5 flat out. The Bene is spanking me at much lower rpm pushing 5000 # more? We both have clean gear and bottoms. He has a sail drive and a Gori folding prop. I have a shaft. I fairly certain I have a problem. Opinions? What performance do you get with the same engine ?

Just for reference, my 44DS 4JH4E with 18 inch MaxProp normally runs at 2300 RPM which moves her at around 7.5 kts. Clean bottom. I have calibrated the OEM tach and it is pretty close, within 20 RPM. At 2500 RPM she is nudging 8 kts, flat water, no headwind. I have never opened it up to MC at 2900 RPM but I'd guess that would be around hull speed which is about 8.5 kts. The pitch setting on the Max Prop is tricky. Did you set the pitch based on conversation with PYI? Based on my knowledge of my boat performance I have trouble seeing the Bene doing 8 kts at 2200 RPM.

 

[Will Gilmore]

H41 DS has a waterline length of 35.5' or 10.82m. This would give you a hull speed of 35.5'^(1/2) x 1.34 = 7.98 knots
and the Beneteau Oceanis 45, with a LWL = 42' or 12.8m has a hull speed of 42'^(1/2) x 1.34 = 8.68 knots.
What does "spanking you at much lower RPMs" mean? A two knot difference? Because after the hull speed is reached, increasing RPMs would not pay off with much more speed. You'll get some, but the thrust to gain ratio really takes off after that.

It does, however, sound like the Maxiprops have a history of dissatisfied customers.

- Will (Dragonfly)

 

[Don Lucas]

Just for reference, my 44DS 4JH4E with 18 inch MaxProp normally runs at 2300 RPM which moves her at around 7.5 kts. Clean bottom. .

thats real hard to believe!

 

[kappykaplan]

It does, however, sound like the Maxiprops have a history of dissatisfied customers.

I'm not one of them!

 

[SG]

I don't believe that it's the MaxProp. It's probably the pitch.

By the way, for every one of the Flex-O-Fold Gold props that's sold, there must five Maxprops sold.

If I were buying a folding prop, I would likely buy a Flexi-O-Fold. Please don't take my observations as a critism of them. If I were buying a feathering one, I would likely buy a MaxProp, as most people do.

There are some advantages to a feathering prop over a folding one in terms of cruising reliability (If you have ever been on a boat with a sfolding one that doesn't either fold or deploy right.). I think that if you keep your (boat's) bottom clean and the prop maintained the folding props will work. However e MaxProps the feathering props are more reliable. .

On the other hand, many more sailors are happy and rely on their MaxProps for a reason. I have known a bunch of sailors that have called MaxProp for second and third generation props with questions, they get treated like hey were new purchasers.

 

[Rick486]

I'm not one of them!

Me either. Couldn't be more pleased.

 

[Rick486]

thats real hard to believe!

Not really important to me or anyone else what you believe or don't believe.

 

[dakno]

Thanks everyone. My bottom was cleaned the day before we left Mississippi with a good report from the diver as I stood on the pier and he has been cleaning this boat every 60 days for the past year. The 12 pitch is what the new specs stated which came with the boat from the Hunter broker in Kemah who sold the boat new in 08 to po. I am the second owner. My rpm's max at 3250 but I am fairly sure that the revs are governed. The pitch was set by the vendor/mechanic/boatyard in Seabrook, Tx. I don't want to name names but we had issues( the day of our leaving Tx, stopping 1st at the boatyard for a quick haul and prop install) they had a 2 blade prop instead of the 3 blade we had ordered and coated with propspeed. Vendor insited it wasn't an issue and increased pitch to 14. We attempted to leave Tx but weren't getting any power. Returning to the haul out yard he then pulled the prop and reset to 16 pitch. We set out again but still not enough power for a several hundred mile trip. Returning to boatyard for the 3rd time that day yard owner wanted to change the 2 blade Max-Prop to 18 pitch. A this point I had had enough and canceled the trip, told the yard that the boat engineers at Hunter/Yanmar decided on a 3 blade 18", 12 pitch prop, which I had paid for and thats what I wanted. 1 month later we sailed/motored to New Orleans, engine is 4JH4E OR 4JH4AE, with a 3 blade Max-Prop, supposedly 18" D and 12 pitch...What I am really asking is that my 20,000# 08 H41 with the upgrade Yanmar 54 should run in flat water 6 knots at 2200 rpm and max out at 7.25knots at 2900rpm; by saying that the 25,000# Beneteau was spanking me means that I in no way could keep up with him at any rpm. Again, bottoms clean, same engines, different displacements.?

 

[Will Gilmore]

H41 DS (LWL 35.5') = 19400lbs (8800 kg) vs Oceanis (LWL 42') = 21048 lbs (9547 kgs)
Some of the answer depends on which Beneteau was spanking you. The Oceanis should be out performing you. She only displaces 2000 more pounds with a lot longer waterline. There is 3/4 of a knot difference in hull speed; that's a fair percentage of your max speed. If you are loaded for a long trip and she was just out for a daysail you might have weighed nearly as much. The 45FS, on the other hand, has a LWL 36.75' with a displacement of 20570 lbs and the First 456 has a LWL of 39'4" at a displacement of 26500 lbs. They all have more length, but the First weighs a lot more. The First should have been putting more effort into her headway than you. You know the RPMs of the other boat by radio contact or were you in convoy and both loaded similarly for the same trip? Do you have a baseline of past data to compare? You have tried three different pitches on a two blade prop and now a three blade prop and noticed no change in performance. It sounds like you are near the limitations of your hull.

-Will (Dragonfly)

 

[seadaddler]

I got my brand boatin 2007 and with a 3 blade prop from dealer and was not happy having hard time getting 6 knots boat speed motoring with flat water.
I decided on a Flex O Fold 3 blade and now can do 7 plus and so I do believe proper pitch makes a big difference.
We have friends with same boat and max prop and some much less
haul speed and must be not proper pitch I think.
Nick

 

[RoyS]

I would increase pitch until the motor cannot reach full rated RPM and then dial back one notch in pitch. At that point you should have the right setting. You can do this over several seasons. I do not recommend trying to change pitch under water. Parts can be lost and mistakes can be made. Put me in the satisfied Max prop column.

 

[dakno]

Thanks all, this is a great forum. The Beneteau is a 2012, not sure what model other than no Oceanis markings and she looks like a racing sled. Owner claims a dry displacement 25k. My dry displacement is 19.5k. I talked to PYI (Max-Prop) today and they(without knowing transmission and without any certainty of what the actual angle the prop was set at) felt that likely since my boat was maxing rpm at 3250 I should change angle to 22 degrees( a 12 pitch is equalivant to 20 degrees). If the B45 has a LWL of 42', my H41 is LWL 35.5, that 6.5' difference would explain some things..but still the 25% greater displacement and extra drag of the larger vessel with the same HP as the lighter vessel should mitigate some of this. The B45 also is a sail drive? When I return to the boat I will get the transmisson info and call PYI again. BTW, They looked up the original vendor and were able to tell me the exact prop I own from their records. You all have been very helpful. Thanks again

 

[Maine Sail]

Yanmar wants the prop pitch to be adjusted so the engine can make slightly more than max rated RPM, about 50-100 RPM over the max RPM rating (spec is 100 RPM over max), in current free water, at MAXIMUM throttle.

So if your engine is 3000 RPM then it should be able to attain 3100 RPM at maximum throttle in current free water. This is best confirmed with a digital photo tach.

First confirm you engine can rev to +200 RPM over the max rated RPM, in neutral, then give it a test run. It should not be so shy that it's under-pitched, and it must be able to at least attain the maximum rated RPM.

Over-pitching, when you can't attain max RPM, is worse than under pitching, but under pitching will result in less speed at a given RPM.

You can't base a Max-Prop's pitch off a fixed pitch factory prop pitch. They are two entirely different props...