Opinions on folding/feathering propeller

[Fogg 427]

It takes a pretty severe impact to knock off a propeller. When did that last happen to you?

I’m referring to the more realistic scenario where you run over a piece of wood too small to easily spot and the first you know is the brief sound of the prop touching it as it passes underneath. I’ve had this several times over the years. Admittedly more in Europe than in NZ but it’s still happened to me here. No prop damage to a metal blade but I don’t fancy my chances with a plastic blade or the prospect of a rough motor to a haulout facility.

[Cantab 341]

There seems to be lots of stories about how easy it is to fit a new blade and how cheap they are for Kiwiprops.

Makes you wonder about why so many people with the experience.

Bit like people that rave about the after sales service and warranty replacements from xyz company, why the hell do they need it so often?

I would rather have something that didn't break in the first place.

[Island Time 1,284]

Well, I did 30,000 odd NM with one Kiwiprop. Never changed anything. Wrapped rope around it 3 x, once sufficient to stop the engine. Hit several bits of floating timber etc with the boat. No problem. The blades are much tougher than many think, but if you do damage one, easy to change, and cheap. Metal props can be damaged as well, nothing is bulletproof.

[Cameron 93]

On 17/08/2020 at 1:50 PM, windmill said:

Hi everyone,

We're seeking a 16x11 LH folding prop to fit to a Volvo 120S saildrive and 18HP engine, on a Farr 1020.

Thank you

Got this prop available...  Off a Volvo D1-20 motor and sail drive on a Farr 1020...Genuine Volvo prop... ph 021 2267662 

[Fish 0]

6 hours ago, Aleana said:

I can never get my head around a mission-critical component like a prop being made of plastic when plenty of good metal options exist.

The lack of weight at the rotating tips (kiwiprop) make a massive difference to vibration. You can have a dog eared blade and not really notice. You will get a slight reduction in efficiency, but nothing mission critical. Conversely, folding props need quiet a lot of weight in the tips, so any imbalances are instantly felt. I don't have the personal experience, but I understand wear can lead to imbalances, and any damage will be amplified due to the weight in the tips. Granted, they should be harder to damage, but wear in the gearing mechanisms is normal.

But hey, props are a personal preference. We've had a kiwi for near 20 years and are happy with it. Others have had other types of props for a lifetime and been happy with them too.

You can adjust the pitch yourself very easily, so optimise it to your engine / gearbox set up and boat, as opposed to taking an educated guess with a 'fixed pitch' prop, handing over the few thousand dollars, then seeing if your engine laboured, or you're under-propped and can't get near hull speed 

[Frank 157]

On 5/08/2018 at 1:45 PM, nagy592 said:

Lots of great info, I learned again. Actually I have to check the clearance between the shaft end and the rudder. In memory I have plenty of space, but looking this picture (one of the 15 Chargers) not as great as I remembered.

It looks like a feathering two blade on the picture...  maybe a reason for it. 

Conclusion: due the engine size and the nature of Kiwiprop that is out, let see the available space and go from there. The preference is geared folding type (two or three blade)... but who knows

Thanks for the comments anyway

 

She is a pretty looking vessel what is the design ?

[2flit 52]

We switched from a  new Gori 2-blade  (not the racing prop)  to a MaxProp 3-blade about three years ago. We have a Yanmar 3GM30F engine in a Farrier Trimaran.

We had a fair bit of vibration with the Gori and the reverse performance was very poor.  Our forward cruising speed under motor is a bit more solid maybe  almost +1 kn and the reverse power is like night and day. Manoeuvring  a 8+ meter wide boat in marinas with a single engine has been better (far better) with the MaxProp.  We have allot more prop walk in reverse with the MaxProp.  I expected more impact on sailing performance  from switching to three blade feathering but it has not made a difference to us under sail. We don't get above 13 knots as often as we used to since loading the boat up with cruising gear and this weight related slowdown has proven to be so dramatic that it might be masking the added prop drag.

When we stop cruising and take all the added weight out of the boat, I would probably switch back to a two blade folder.  We used to be able to go 16kn  fairly close to windward and faster off the wind so changing to lower drag would become important again. This changeover will require a new prop shaft since we cut ours down to fit the MaxProp's  odd fitting arrangement.

 

[rossd 16]

On 5/08/2018 at 7:12 PM, Jon said:

As for the OP I’d be going Briski two blade geared folder

Briski are good , custom made in a couple of weeks. I got a floppy folder. They say the advantage of geared over floppy is longer life only, no difference in performance.

[Cantab 341]

So the bad news today, on top of the already bad news,

Briski no longer make the "floppy" folder Props

The next options start at around twice the price, not enjoying this one.

[Adrianp 124]

I replaced my worn out 2 blade folding Briskis in 2018 for a pair of 2 blade folding Goris. 

The Goris were only 10% more expensive than the Briskis! Been great props so far. 

What was painful was taking one of the Briskis to the scrap metal yard..........

 

 

[Cantab 341]

So I ended up with Flexofold https://flexofold.com/

Got quotes from 4 suppliers, they were the cheapest and also shortest delivery time. You deal directly with the manufacturer which was very easy.

The prop is a very nice looking unit, engineering is superb. The prop actually folds under its own weight when vertical, it drives the boat well forward and reverse, highly recommend.