Kiwi Prop experiences

[Gypsy23]

I have a Hanse 370 with Yanmar 3YM30 engine and SD20 saildrive fitted with a 2 blade folding prop. Not sure of the manufacturer but maybe FlexoFold. This boat is new to me. I previous cruised a 2002 Bavaria 44 with D2-55 and M25S with 3 blade Volvo folding prop.


On a recent outing with the Hanse when motoring through a very disturbed area around the Sydney Harbour Bridge (commonly known as the washing machine) I felt the motor/prop combo was underpowered for the messy waters. It made me think about a 3 bladed prop to deal with these type of conditions.


I have seen info about the KiwiProp which looks interesting.


Any forum readers care to give their experience with Kiwi Props on the same engine/SD combo or other combination? Good and bad please.


Any comparison with other feathering or folding props.


Thanks in advance. This forum is always a wealth of knowledge so I hope I can get some 'real-life' comments on the subject.

[Pete7]

No experience of Kiwi propellers, but I put a copy of a YM review in the library under systems which might be interesting reading. Performance isn't great compared to some of the others but the price is:

http://www.cruisersforum.com/forums/downloads.php

[Gypsy23]

Originally Posted by Pete7

No experience of Kiwi propellers, but I put a copy of a YM review in the library under systems which might be interesting reading. Performance isn't great compared to some of the others but the price is:

http://www.cruisersforum.com/forums/downloads.php

Thanks Pete, I'll take a look.

[Pete7]

The one thing worth noting is they changed the design of the blades after the review. Whether that made any difference or not is debatable.

Pete

[belizesailor]

I switched from 3 blade fixed to 3 blade Kiwi a few years ago. Performance under power about the same except WAY over propped in reverse. Kiwis go to full pitch in reverse and this is not adjustable so you will be over propped in reverse.

No issues with the props otherwise.

[Pete7]

Was there a noticeable improvement under sail?

Pete

[Steven UK]

My new boat has a kiwi prop in the little motoring and maneuvering I’ve done I haven’t experienced any issues, I just removed it to change the cutless bearing and it is indeed an interesting thing. It’s a conventional layout not saildrive.

[belizesailor]

Originally Posted by Pete7

Was there a noticeable improvement under sail?



Pete

BIG TIME for me since the originals were fixed 3 blade (bullet proof, but big drag). Should have gone to folding/feathering a long time ago.

If I were to do it over again, I would give Flexofold a serious look. Their improved performance under power is appealing.

[kenbo]

My 3 year experience with a 19"x 22° 3 blade KiwiProp on an 11 ton, 40' monohull with a Yanmar 56hp with 2.62:1 reduction on a shaft drive. Before the installation I had a 3 blade 18x14 fixed propeller that was perfectly sized for the boat allowing me to get to 50 RPM of max RPM.

Pros

• Since the hub and boss was SS on a SS shaft there was no galvanic issues at all. The shaft zinc would last for years.
• Noticeably better sailing performance. I won't quantify since all boats are different but it was a noticeable improvement in less than 12 kts of wind. Tacking in light air was much improved as well.
• The prop is very light and seemed to be well balanced, motoring vibration was negligible.
• the prop's blades align with the flow of water without locking the gearbox in reverse. A big plus if you have a Yanmar or other cone clutch gearbox. Yanmar will void gearbox issues if the damage occurs from locking the gearbox in gear while sailing.
• The price is very attractive vis a vis other feathering props.

Cons

• The blades have poor lift and I believe that's why the manufacturer is going with a modified ogival blade design, to increase lift. Someone on this site once said it was like "beating 3 sticks in the water". That's a bridge to far but the blades are a sub-optimal design.
• My fixed blade prop would drive the hull to 8.2kts in calm water. The Kiwi only 7kts and yes I played with the pitch settings to no avail. After much thought and discussion with the manufacturer I came to the conclusion that a combination of blade shape and blade area prevented the prop from delivering all of the shaft HP to the water. The 4 blade Kiwi with the ogival blades may have improved this but I didn't go in that direction.
• Reverse is powerful since it's always fully pitched so you have to learn to back with the gear shifter rather than the throttle, my experience yours may vary.

You have a lower hp'd engine so power delivery to the water may not be and issue. But I tend to agree with the results of the Yachting Monthly test, the KiwiProp has a hard time delivering the shaft hp to the water compared to other props.

[Gypsy23]

Thanks for comments so far.

I wonder if anyone has experience of the new shape blades.

[Fidsplice]

I’m a huge fan. I’ve had a kiwiprop (3 blade) on my Farr 1020 for around 10 years now. Simple to maintain, great in reverse. Better than my previous volvo 2 blade.

No penalty sailing. Tunable pitch, and I had better boat speed than with the 2 blade. Repowered from the original 2002 to a volvo D1-30 and tuned pitch to suit.
Without changing to another prop, I can’t offer a comparison! But I am very happy. I can compare my boat’s performance to other Farr 1020s and I carry no penalty.

I think it is a product that deserves more attention than it gets. And I have no interest at all in the product other than being a happy customer, and love the characteristic ingenuity of New Zealanders. They do good stuff.

[Gypsy23]

Thanks Fidsplice for your input. Good to have practical experience in the mix.
I agree with the sentiment of Kiwi ingenuity, I hope we Aussies haven't totally lost that gene, but it tends to get swamped amongst the bigger players.

[Davo1404]

A bit late to the topic. I have just returned from 6 months of cruising the Queensland coast. I have always used a Gori 2 bladed folding propeller on my Yanmar 2gm20f. This year replaced it with a Seahawk 3 bladed stainless folding propeller. This propeller is a beautiful piece of engineering & has made a huge difference when motoring into a head sea. Also smoother & made in Victoria. Check out the link. I purchased the Slipstream model

http://www.seahawk.com.au/

[malbert73]

Go flexofold 3 blade. Like a fixed prop in forward and perfectly fine in reverse. Minimal drag sailing and no snagging of stuff under sail on feathered blades

[Jon Hacking]

We've been playing with Kiwi Props since 2010, with several iterations of blades. Our engines are a bit bigger (4JH2, 48hp, SD31 saildrives).

Sailing performance is certainly improved over our fixed blades. But that would be true for any folding or feathering prop.

As Kenbo noticed in his excellent post, motoring performance is not as good with ANY feathering prop. Feathering props tend to have flat blades, so only one part is really giving optimal thrust. And the thick, plastic blades seem to be harder to spin in the water for the amount of lift they deliver. These seem to be a design trade-offs. (But our Gori folding props developed wear at the pins after a few years, so that's a folding design trade-off).

Like BelizeSailor, we don't like the max pitch in reverse. I've argued this with John Blundell back & forth, but he won't change. He says it's to get the power quickly in a crash-stop situation, but I can move my throttle down pretty quickly, thank you. I'd MUCH rather have my power more controllable. I've even considered adding a few strips of fiberglass where the reversing boss rubs against the blade, to decrease it's pitch a bit, but haven't actually done it (yet).

In the meantime, I can't get my Yanmar engines higher than 1400rpm in reverse (typically, when setting the anchor). If you can't get the rpms up, the engines can't develop rated power, so we actually get LESS power into the water in reverse with this (silly, IMHO) max-pitch in reverse design.

Also, we find the blades get pretty dinged up with time. John says it's due to us hitting things. I can't really refute him, as I can't guarantee that we haven't hit things in the water, but our other props don't have this problem. Right now I'm getting a pretty severe vibration out of one side, so I need to go check the blades again. Unfortunately, you can't mix old & new blades, as they're different weights.

We're still using them, but we're looking for other options. The KiwiProp's big advantage is price (& John's very responsive to questions & service requests) but I'm now thinking it might be worthwhile spending a bit more.