Does anyone have experience of fitting a Kiwi Feathering Prop to an F33.? I'm interested in the fit - it's a 17' dia - and performance, especially reverse.
Regards,
Chris L-B
Kiwi Prop
-
Mike Holibar
- Posts: 174
- Joined: Mon Jun 01, 2009 12:41 am
Re: Kiwi Prop
Chris, I fitted a Kiwiprop to my boat last summer and it transformed the boat. I couldn't be happier with the result - more speed, better upwind performance etc. and we now find that we use the engine a great deal less.
The one I purchased was second hand with 17" blades. That owner was unhappy with its performance but it was clear from his explanation that he did not understand how to get the best out of propellers and engines.
The suitability of your 17" prop will depend upon your engine rating and reduction gear. The link below will give you a good guide. In my case , 50HP @ 3000 rpm, reduction 2:1 I was slightly underpropped with 17 on maximum pitch. Kiwiprop sell replacement blades at NZD100 each so I changed to 18".
Generally speaking hp relates to diameter and pitch relates to speed which is why I went to the larger prop, but set to 22deg pitch. I noticed reduced vibration and prop noise due to lower rotating mass, altogether much better than the old fixed pitch prop.
Performance under engine has been affected, a slight reduction in top speed maybe 1/2 knot. Astern performance is not that good and I need to check this out further. It seems like the pitch astern is far too great so there is plenty of bight but the engine cannot pick up revs meaning that although I can stop reasonably well there is infact very little power available. This problem is discussed on the KP website and I have checked that the feathering mechanism works freely as this is usually the cause.
I have yet to check the Hurth gear ratio astern, this could be another explanation. It is very important that your engine develops its full rpm under load as that is the only way it can develop its rated power. Have a look at the website and see if you can spot any installations similar to yours and that will give you an idea of pitch and dia.
Also on the website are two different shaft configurations, metric and sae tapers I think, and you need to order the correct boss for your shaft. In my case the the shaft was one size larger than the KP boss was made for, so I had the shaft machined to suit. It is important to take care that the taper is a very good fit. Kind regards,
http://www.kiwiprops.co.nz/bench-p2.html
The one I purchased was second hand with 17" blades. That owner was unhappy with its performance but it was clear from his explanation that he did not understand how to get the best out of propellers and engines.
The suitability of your 17" prop will depend upon your engine rating and reduction gear. The link below will give you a good guide. In my case , 50HP @ 3000 rpm, reduction 2:1 I was slightly underpropped with 17 on maximum pitch. Kiwiprop sell replacement blades at NZD100 each so I changed to 18".
Generally speaking hp relates to diameter and pitch relates to speed which is why I went to the larger prop, but set to 22deg pitch. I noticed reduced vibration and prop noise due to lower rotating mass, altogether much better than the old fixed pitch prop.
Performance under engine has been affected, a slight reduction in top speed maybe 1/2 knot. Astern performance is not that good and I need to check this out further. It seems like the pitch astern is far too great so there is plenty of bight but the engine cannot pick up revs meaning that although I can stop reasonably well there is infact very little power available. This problem is discussed on the KP website and I have checked that the feathering mechanism works freely as this is usually the cause.
I have yet to check the Hurth gear ratio astern, this could be another explanation. It is very important that your engine develops its full rpm under load as that is the only way it can develop its rated power. Have a look at the website and see if you can spot any installations similar to yours and that will give you an idea of pitch and dia.
Also on the website are two different shaft configurations, metric and sae tapers I think, and you need to order the correct boss for your shaft. In my case the the shaft was one size larger than the KP boss was made for, so I had the shaft machined to suit. It is important to take care that the taper is a very good fit. Kind regards,
http://www.kiwiprops.co.nz/bench-p2.html
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
-
chrislloydbostock
- Posts: 6
- Joined: Thu Jun 11, 2009 8:26 pm
Re: Kiwi Prop
Thanks Mike,
I did look at the Kiwi Prop website. Extremely comprehensive.
My old 23hp Volvo dropped it's guts after a big dose of seawater in the head and I'm replacing it with a 29hp Nanni. Problem is this revs at 3600 and is right hand with 2.6:1 reduction, whereas the old motor maxed at 2500 with 2.36:1 reduction and was left hand. So I'm going to have to replace the old prop anyway - and I thought I'd look at a Kiwi. John Blundell from Kiwi has recommended a 16.6" nominal (17" at tips for space) X 22deg prop for my installation.
Does that sound about right to you?
They claim that you can adjust the pitch with the boat in the water, so maybe there's some room to experiment if the factory setting's not quite right.
What are your thoughts on the prop's durability.? Well made? easy to service? Was it easy to change your blades?
Regards,
Chris L-B
I did look at the Kiwi Prop website. Extremely comprehensive.
My old 23hp Volvo dropped it's guts after a big dose of seawater in the head and I'm replacing it with a 29hp Nanni. Problem is this revs at 3600 and is right hand with 2.6:1 reduction, whereas the old motor maxed at 2500 with 2.36:1 reduction and was left hand. So I'm going to have to replace the old prop anyway - and I thought I'd look at a Kiwi. John Blundell from Kiwi has recommended a 16.6" nominal (17" at tips for space) X 22deg prop for my installation.
Does that sound about right to you?
They claim that you can adjust the pitch with the boat in the water, so maybe there's some room to experiment if the factory setting's not quite right.
What are your thoughts on the prop's durability.? Well made? easy to service? Was it easy to change your blades?
Regards,
Chris L-B
-
Mike Holibar
- Posts: 174
- Joined: Mon Jun 01, 2009 12:41 am
Re: Kiwi Prop
Chris,
John really knows his stuff and I would trust his advice. The pitch and dia sound about right to me. The pitch is very simple to adjust, just a grub screw on each blade. From memory 1/3 of a turn = 1 degree of pitch. This is quite a fine adjustment and each blade must be adjusted by exactly the same amount so you would need to be very steady underwater to do a proper job. The prop is well made, very easy to service and equally easy to change blades. Replacement blades are very reasonably priced. It's only a matter of tapping out a pin to remove a blade. I haven't seen anything about the prop that would worry me re durability and all reports I have heard are positive except where someone has "overpitched" the prop and not been happy with the resulting poor engine performance. However it is important to closely follow any instructions re fitting, assembly and servicing. Kind regards,
John really knows his stuff and I would trust his advice. The pitch and dia sound about right to me. The pitch is very simple to adjust, just a grub screw on each blade. From memory 1/3 of a turn = 1 degree of pitch. This is quite a fine adjustment and each blade must be adjusted by exactly the same amount so you would need to be very steady underwater to do a proper job. The prop is well made, very easy to service and equally easy to change blades. Replacement blades are very reasonably priced. It's only a matter of tapping out a pin to remove a blade. I haven't seen anything about the prop that would worry me re durability and all reports I have heard are positive except where someone has "overpitched" the prop and not been happy with the resulting poor engine performance. However it is important to closely follow any instructions re fitting, assembly and servicing. Kind regards,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
-
chrislloydbostock
- Posts: 6
- Joined: Thu Jun 11, 2009 8:26 pm
Re: Kiwi Prop
Many thanks Mike,
It's helpful getting an independent view.
Chris
It's helpful getting an independent view.
Chris
-
Mike Holibar
- Posts: 174
- Joined: Mon Jun 01, 2009 12:41 am
Re: Kiwi Prop
Chris, how did things work out? Did you get your Kiwiprop? cheers,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand
-
chrislloydbostock
- Posts: 6
- Joined: Thu Jun 11, 2009 8:26 pm
Re: Kiwi Prop
Hello Mike,
My new engine installation's been a drawn out saga and I decided to defer the complications of fitting a Kiwiprop until I' m ready. I picked up a right hand fixed prop locally to get me going. One issue that did concern me was specifying the shaft taper accurately for a Kiwi as I did not want to have to send the prop backwards and forwards for re-machining. I've now got the taper properly measured so will probably go for a Kiwi next time I haul out.
Thanks for your interest.
Chris
My new engine installation's been a drawn out saga and I decided to defer the complications of fitting a Kiwiprop until I' m ready. I picked up a right hand fixed prop locally to get me going. One issue that did concern me was specifying the shaft taper accurately for a Kiwi as I did not want to have to send the prop backwards and forwards for re-machining. I've now got the taper properly measured so will probably go for a Kiwi next time I haul out.
Thanks for your interest.
Chris