Propeller data poll

[skippy2]

Hi,
I'm in te process of changing the 2 blades fixed prop of my SO35 equipped with a Yanmar 3YM30 and 2,62:1 transmission reduction rate.

The final choice is between 3 blade Flexofold folding and 3 blade MaxProp feathering.

To facilitate the choice, I'm trying to collect some useful data from users with the same boat (easy in this group 😁😁) and the same Engine/Transmission.

In detail I would need to know your:

-Prop type (Producer/Model)

-Blades (number)

-Diameter

-Pitch

-an example of RPM/Speed averagelly achieved.


Thanks everybody, hope this will help someone else!

[Zanshin]

I've never known my prop's pitch and diameter and am not sure that many here do, either.

I've had a 2-blade fixed (43DS), Gori 3-blade (49DS) and now a 3-blade Flexofold (J57). The Gori was my favorite with good reverse performance and a wonderful "cruising mode" overdrive feature. The Flexofold is very good but I feel it is a bit lacking in reverse performance.

[Don Reaves]

My boat is a 2004 SO35 with Yanmar 3GM30F engine and KM2P transmission. The forward reduction is 2.61 and the reverse reduction is 3.06. I switched to a 3-blade 16.6" feathering Kiwiprop in 2007 and have been very happy with it. It has a very simple mechanism without gears. I have never had it fail to switch from forward to reverse. Just lubricate it before launch.

I typically cruise at 2900 RPM, which give me 6.6 knots of speed through the water. According to the Sail magazine article that has been referenced a number of times on the forum, the Kiwiprop is at the lower end for top speed among the props tested, but was rated fairly well on other metrics. I trust their measurements, but would recommend you disregard their comments about how the Kiwiprop works. They clearly didn't understand the mechanism, and drew some incorrect conclusions.

edit: I may have referenced the wrong publication.

[ronparker]

Have you seen this review: www.flexofold.com/upload_dir/docs/Test_YachtingMonthly_low.pdf

[skippy2]

Sept 15, 2021 11:57:13 GMT Don Reaves said:

My boat is a 2004 SO35 with Yanmar 3GM30F engine and KM2P transmission. The forward reduction is 2.61 and the reverse reduction is 3.06. I switched to a 3-blade 16.6" feathering Kiwiprop in 2007 and have been very happy with it. It has a very simple mechanism without gears. I have never had it fail to switch from forward to reverse. Just lubricate it before launch.

I typically cruise at 2900 RPM, which give me 6.6 knots of speed through the water. According to the Sail magazine article that has been referenced a number of times on the forum, the Kiwiprop is at the lower end for top speed among the props tested, but was rated fairly well on other metrics. I trust their measurements, but would recommend you disregard their comments about how the Kiwiprop works. They clearly didn't understand the mechanism, and drew some incorrect conclusions.

Thank you!

[skippy2]

Sept 15, 2021 10:27:50 GMT Zanshin said:

I've never known my prop's pitch and diameter and am not sure that many here do, either.

I've had a 2-blade fixed (43DS), Gori 3-blade (49DS) and now a 3-blade Flexofold (J57). The Gori was my favorite with good reverse performance and a wonderful "cruising mode" overdrive feature. The Flexofold is very good but I feel it is a bit lacking in reverse performance.

Thanks for your reply

[skippy2]

Sept 15, 2021 12:43:56 GMT ronparker said:

Have you seen this review: www.flexofold.com/upload_dir/docs/Test_YachtingMonthly_low.pdf

I do, I actually read it countless times and used it as a reference to choice the  prop for my former boats.
Now I'm trying to collect data about my specific boat/engine combination before making my choice.
Thanks!

[johannes]

On our SO37, we switched from original 2-blade fixed to a 3-blade Flexofold 15x10-3 (recommended by Flexofold). Transmission ratio is 2.21.

Pros: less vibration, noticeably better pointing under sail (and better speed, although hard to quantify).

Con: much worse bite in reverse, although fully acceptable.

We usually cruise at 2700 rpm at 6.2 knots in calm water. It was about the same with the fixed prop.

[skippy2]

Sept 15, 2021 15:42:27 GMT johannes said:

On our SO37, we switched from original 2-blade fixed to a 3-blade Flexofold 15x10-3 (recommended by Flexofold). Transmission ratio is 2.21.

Pros: less vibration, noticeably better pointing under sail (and better speed, although hard to quantify).

Con: much worse bite in reverse, although fully acceptable.

We usually cruise at 2700 rpm at 6.2 knots in calm water. It was about the same with the fixed prop.

Thanks for reply!

[kev]

Sept 15, 2021 15:42:27 GMT johannes said:

On our SO37, we switched from original 2-blade fixed to a 3-blade Flexofold 15x10-3 (recommended by Flexofold). Transmission ratio is 2.21.

Pros: less vibration, noticeably better pointing under sail (and better speed, although hard to quantify).

Con: much worse bite in reverse, although fully acceptable.

We usually cruise at 2700 rpm at 6.2 knots in calm water. It was about the same with the fixed prop.

Hi

I have a 36i with the 3YM30 engine and a TuffTorq 2.62:1 gearbox. Bought a 3 blade Flex-o-fold in 16"x12 and very happy with the performance.

I can echo what Johannes said. Plus somewhere between 0.5kt and 1.0kt better speed under sail. To stop the boat needs a good burst at higher revs in astern initially, then back the revs off once the blades are open and biteing. So different technique when entering a berth, but perfectly ok once you're accustomed to it.

Recommend you talk to an expert (Flex-o-fold were very good at advising) as there are different combinations of pitch and dia available for this engine/gearbox. Suggested to me were  either a 17x11 or a 16x12. Possibly the combo I selected is slightly under propped as the engine is very free revving in forward, however, I can get 7.5 kts with clean hull and around 3400rpm (I try not to use the max of about 3600 that I can get). I generally cruise at around 3000rpm at similar speed to Johannes, but this is very dependant on how clean the prop is and I can easily loose a knot with a fouled prop.

regards


Kevin

[zaphod]

Once you have decided which prop to get, the prop manufacturer will be able to tell you which prop is appropriate for your boat.

Flexofold in particular knows what your boat needs because they are an oem supplier for Jeanneau. They have matched thousands of their props to Jeanneaus.

I went with Flexofold on my 39i and they nailed it! My boat powers slightly faster than it did with the fixed 3 blade, and of course sails much faster. (Up to 1 knot faster in some conditions).

[skippy2]

Thanks to Kev and Zaphod for reply

[andreshs1]

Hi there

when I got mine a few years back, I simply asked Flexofold to provide the specifications as per my boat model, and they did a great job, even contacted Jeanneau.

Great communication and service overall, and I am thrilled with the performance

cheers

[so40gtb]

I put a 3-bladed Kiwi on our first Jeanneau, a SO34.2, and it was far better than the fixed 2-blade factory prop. Our SO40 came with a 3-bladed MaxProp, which we're very satisfied with. It has better "bite" in reverse than the Kiwi, though a bit more prop walk. I don't have the detailed specs immediately at hand. Normal speed/rpm with the Yanmar 4JH3E and standard gearbox is approximately 6.0/2000, 6.5/2200, and 7.0/2400. We don't try for higher speeds because of the much higher fuel consumption, once past 6½-7 kt.

[NZL50505]

Of all the props I’ve had (fixed, folding & feathering) I’ve found 3B feathering Maxprop the best because it has given the most even all-round performance (fwd, reverse and sailing). My current boat (50DS) has one and when in reverse it’s so strong that I can reverse out of the berth by simply engaging slow astern at idle with no additional revs. And propwalk is so negligible that I have actually forgotten which way mine is - I literally can’t tell when I reverse.