Flexofold size for a 2007 B49 with Yanmar 75hp and ZF30M?

[boom23]

Hi all,

I am looking at a 2007 Beneteau 49 with the 75hp Yanmar engine (3000-3200 max rpm) and ZF30M (2.15F, 2.64R) and the stock (I assume) fixed propeller. The markings on the propeller are not visible.

During the sea trial, the boat reached 9kn at 3500rpm (assuming the Yanmar gauge is correct). The alternator is stock. She weighs 30,000lbs.

Isn't this too high of a max RPM?

Also, Beneteau offered a 19x11 Flexofold (up to hull #87) or 18x13 (starting hull #88).

Flexofold person recommended 20x13 to reach 3000rpm or 20x12 to reach 3200rpm.

What do you think about flexofold propeller size?
What do people use and what are the speed/rpm numbers?
What would be the right prop size?

Thank you for any info.

[Kijit]

I don't know anything about that engine, and our boat and engine are quite different, but we recently put on a Flexofold prop. The recommendation of the Flexofold folks, for us anyway, seemed to be right on, and we are quite happy with it so far. Just a data point.

[boom23]

Thank you Gerhard. It is a good data point.

I am inclined to go with the Flexofold people recommendation. I am still curious about what speed and RPM the people who got the factory option flexofold are getting. The factory option prop is 2 inches smaller in diameter, and one inch more in pitch. That's a big difference.

[Jim Cate]

FWIW, when we installed our F-O-F, the size recommended by the folks at the dealer was exactly right, reaching the red line just at hull speed, so there's another one they got right. Re the size on the Bennie: remember that the price if those props goes up with diameter, and perhaps their decision was fiscally determined. Additional pitch does not change the price...

Jim

[MickBeth50]

boom,

i have the oceanis 50 with a yanmar 4JH4-TE with a SD-50. Flex-o-fold recommended the 3-Blade 20x13L.

i installed it last spring and am very happy with it. I get 9.5 kts at 3200 rpm. but am generally cruising at 6.5-7 at 2000 rpm.

mike

[boom23]

Originally Posted by MickBeth50

boom,

i have the oceanis 50 with a yanmar 4JH4-TE with a SD-50. Flex-o-fold recommended the 3-Blade 20x13L.

i installed it last spring and am very happy with it. I get 9.5 kts at 3200 rpm. but am generally cruising at 6.5-7 at 2000 rpm.

mike

Mike,
the SD50 has 2.32 reduction ratio forward and reverse. This indicates to me that since I have 2.15 reduction forward, the 20x13-3L will be too much for me.
Thanks for the info.

P.S. Keep an eye on the SD50. Once you get a hint of clutch slipping, get the cone clutch re-lapped or replaced.

[boom23]

I used a prop calculation program to figure out the difference in prop size/pitch between 2.32 (Mike's SD50) and 2.15 (ZF30M).

The difference is only 1" in pitch.

So, it seems that the Flexofold people recommendation for a 20x12-3R will be just right to achieve 3200rpm!

[George DuBose]

Hello CruisersForum,

Diameter and pitch are a mystery to me. At least to understand which combination would be best for my boat and motor.

When I bought my FOF 2-blade, the salesman just asked me the make of my engine. The original blades wouldn't close because they hit the skeg.

The Flex-o-Fold blades I have now are 15x13 RH. I lost an inch of pitch from the original fixed bladed prop.

Any comments?

Thanks,



George DuBose,
Thank you for your email.
Unfortunately, we can´t offer you the propeller size requested (15x14R).
This as the diameter/pitch is not a good propeller combination.

Best regards,
Keld Willberg
Sales & Marketing Manager


Flexofold ApS
Bramdrupvej 50
DK-6040 Egtved
Tel. +45 75 55 43 46
Fax +45 75 55 43 66

Folding Propellers - Flexofold





-----Oprindelig meddelelse-----
Fra: George DuBose [mailto:boss@george-dubose.com]
Sendt: 1. december 2014 18:54
Til: Keld Willberg
Emne: question

Dear Mr. Willberg,

In 2012, I purchased a Flexofold two bladed propellor from your firm directly.

At the Boot in Düsseldorf, the salesman just asked me for my engine and transmission data and delivered to me:

1613R/16-78 (€922,00) for my:

1973 Pearson 36-1
Weight 13500 lbs. - 6.123497 metric tons Engine - Yanmar 3GM30F Transmission is a Kanzaki KM2P with a reduction gear ratio of 2.62 Prop shaft diameter 7/8 inch or 22.225mm Threaded section of shaft reduced to 5/8 inch or 17.145mm The hub of the existing propeller is 65mm long The shaft is removed from the boat, the "key" and keyway are 1/4" or 6.35mm

The 16" blades as delivered could not close due to the skeg before the rudder. You kindly swapped the 16" blades for 15" blades and they fit fine.

However, over the past two years that I have used my boat with the Flex-o-Fold, I have come to realize that I have lost a knot from my former speed (7 down to 6 kts). The fixed prop that was replaced was a
15x14 RH. The Flex-o-Fold blades I have now are 15x13 RH.

In the interest of getting better fuel consumption and perhaps some of my speed back when powering, I am asking your advice about getting a pair of 15x14 RH blades from you.

Thank you for your time.

[YellowBoat]

Try this program: Vicprop - Prop calculator for Displacement and semi-displacement hulls
It gives quite precise results .
Ad

[Captn morgan]

I've had Flexofold props on my last two boats and went with their recommended size. However it should be sized to reach the maximum engine RPMs. My Yanmar 50 HP is rated at 3600 and I can reach that at flank speed. Another recent change from Yanmar is they recommend a cruising RPM at 80% of maximum rather than 75%.

Capt Morgan

[boom23]

I believe the Yanmar 4JH4-TE 75hp is rated at 3200rpm.

[Captn morgan]

Mine is the 4JHE. I was just pointing out that no matter the engine size the correct prop will allow you to achieve the maximum engine rpms.

Captn Morgan