Kiwi Prop... questions after install

[Levin]

Hello all...

So as a few of you might know I own a 2000 Hunter 340 and recently I had it hauled out for a bottom paint job and to have my fixed two blade prop replaced with a feathering 3 bladed Kiwi Prop.

Well so far since I have had the new Kiwi Prop I have to say that I'm not all that impressed with its performance motoring (and only slightly impressed with its performance sailing... although this is harder to determine as I have no idea what exactly my boat would be doing with the older fixed prop at any particular wind angle with any particular wind speed). Basically I was expecting an improvement in motoring performance, and while I did notice less vibration since I moved from the fixed to the Kiwi, I think my overall boat speed has either stayed exactly the same or has dropped slightly at any particular engine RPM.

Right now going into the wind I tend to top out at 6.0 Knots at 3000 RPM. Going with the wind to my back I can get 6.5 Knots (this is in about 15 knots of wind). Toping my engine out at about 3600 RPMs gets me almost up to 7.0 knots (which I believe is my hull speed). If I remember right I think I could do about this with my fixed two blade, which seems strange as I now have a three bladed prop.

Anyway I was wondering if I should change pitch and see if this helps... and if so in what direction (I'm assuming increasing pitch as my engine can still get itself up to 3600 RPMs without black smoke so that means if anything it's under-pitched right?) I was also wondering if others who have the Kiwi Prop noticed similar results when they changed to this prop. Any feedback or advice about whether I should change pitch or whether I'm expecting too much out of this thing would be greatly appreciated.

Take care,
-Levin

 

[Bill Murray]

I too did not get a big change in speed vs rpm when I first installed mine -- after all the initial specs were pretty close to the prop it replaced. I did however modify the settings by 1/2 turn - as instructed by the Kiwi folks. The directions suggested that you make adjustments in exactly 1/2 turn increments until you see the amount of change produced. In my case I am exceptionally plaeased with the results once I did the first change.

Your Kiwi should have come with some very detailed instructions which among other things explain exactly how to do this..... if you don't have yours, let me know and I will scan and post mine for you.

 

[Steve Dion]

Levin:

Your engine is NOT governed by the prop pitch, but by the govener. I think Bill's directions about adjustments are right on. You need to play with the adjustments until you feel that it is maximized. You are correct in assuming that you should still get Max RPMs, but that will probably happened until you are "over-propped".

Prop pitch/sizing is more voodoo than science. They can estimate these things, but until you prove it, it ain't so.

 

[JohnShannon]

I swapped to a Kiwi prop as well, I get much less vibration than the two blade fixed.
I think I sail faster, I am not sure I motor any faster as last year all my instruments blew up.

I suspect the stock pitch for any application would be on the conservative side, bias is to under pitch rather than overpitch

 

[Levin]

Thanks guys...

Yeah I think I sail faster with the new prop... but was disappointed with the motoring performance. I guess I'll mess with the pitch adjustments until I have it where I want it to be (or until I can't get max RPMs anymore... then I'll know I went too far). Oh and Bill, no my prop didn't come with any instructions (was actually surprised by that) but I was able to download them from their website so I saw which allen screw to turn... but thanks for the offer to forward me the manual.

Anyway thanks again for the feedback

-Levin

 

[Steve Dion]

Levin:

I think you should be getting the 7kts (or close to it) at 2800-3000 rpm. Normally the extra throttle is NOT needed unless you are pushing against some heavy wind/tide.

I assume that you have a 3GM? How much pitch do you have cranked in now.

 

[Levin]

Steve,

I actually don't know. I talked with the Kiwi rep before ordering the prop and they put in as much pitch as they felt was appropriate. I agree with you that I figure I should be getting about 7kts at 2800- 3000 RPMs but like I said I get anywhere from a little less than 6.0 kts to as much as 6.5kts or so depending on if I'm going with the wind or against it. Oh and yes, I have the 27hp 30GM30F Yanmar in my 340.

So I figure I must need more pitch or something else is very wrong. I think the prop is the right size because it matches up with my old fixed two blade nicely... so I pitch is the only thing I can think of that might be off.

Anyway thanks again for the feedback.

-Levin