Jump to content

Opinions on folding/feathering propeller


Recommended Posts

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 

Link to post
Share on other sites
  • Replies 56
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

There is some real devil in the detail with propellers. Referring to the yachting monthly test that Farrari referred to, I see there are two versions on the internet: https://www.yachtingmonthly.com

Kiwiprops reverse pitch is not adjustable. There is too much reverse pitch, and therefore torque required to rotate, for some small engines to overcome at idle...

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) no

Posted Images

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.

Shadowfax in the air.jpg

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 ?

Link to post
Share on other sites

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.

 

IMG_4242 (2).JPG

Nov 1st NorthHarborDiesel (1).jpg

Link to post
Share on other sites
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.

Link to post
Share on other sites
  • 1 month later...

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..........

 

 

Link to post
Share on other sites
  • 4 weeks later...

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.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...