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e31 11-10-2003 03:09 AM

best folding prop?
 
I''m considering replacing a two blade, fix prop with a three blade folding prop. Any opinions out there regarding choices and preferences?

Doug

sailingfool 11-10-2003 03:52 AM

best folding prop?
 
You may discover a three blade folding prop to be a hard-to-find item! However, fortunately there are a number of excellent three blade feathering props, and perhaps one of them will work for you.

We a MaxProp which has worked well for us - I consider them the most established feathering prop - you can call PYI for fit info (http://www.pyiinc.com/). Autoprop is another popular alternative. Feathering props are more expensive than folding props so raise your card credit limit before ordering.

If your boat has a two blade as standard equipment, you may not need or want a three blade - again, get advice from someone like PYI on your specific application.

Good luck.

fourknots 11-10-2003 08:35 AM

best folding prop?
 
I''ve got a Max Prop as well and I think you''ll find even a two blade will be superior to anything you have now, especially in reverse.

PYI can repair and service Max-props - it''s good to know that they can be fixed no matter what happens to them. They''ve been very helpful to me over the phone.

paulmcquillan 11-10-2003 08:37 PM

best folding prop?
 
While Gori makes a 3-blade folder, the technical requirements of any folding prop are the oposite of what a good prop should be.

Prop designers say lowest tip mass and thinnest section are goals, but a folder relies on the centrifical mass (weight) at the tips to open the folder.

I can''t say enough good things about the three-blade feathering prop we got for our N41. About $1,250, thin composite blades and a big performance gain.

mcain 11-11-2003 06:06 AM

best folding prop?
 
Paulmcquillan, which brand composite feathering prop did you get for your N41? That cost of 1250 is very low compared to autoprop and the others. What specifically were the performance gains--did you measure them?

paulmcquillan 11-11-2003 06:45 PM

best folding prop?
 
The brand is a Kiwi Feathering Prop.

The composite blades are actually one of the prime reasons for the lower cost (compared to a forged blade) and the exchange rate helps a little. A replacement blade is $50 for comparison.

Since we knew that we were in the market for a prop change, we started keeping notes on perfornance under both power and sail over about six months.

We invested a couple of evenings doing speed runs on a measured mile (both ways) at various rpms. We tracked sailing speeds on numerous wind angles and wind speeds.

There is an older thread called something like "performance gains feathering prop" where I posted most of the detail. The short version is that
- under power we gained +1.5 kts
- under sail, most wind conditions +1.1 kts

mcain 11-12-2003 05:35 AM

best folding prop?
 
Very interesting and intriguing. I had just about dismissed feathering props because of the cost issue--the performance gains were probably not worth the high cost. How is the construction? Very robust? How long have you had it? I wouldn''t think composite blades would be as reliable and last as long as bronze blades?!?

paulmcquillan 11-12-2003 09:08 AM

best folding prop?
 
Construction is robust. Because there are no gears, the composite blades pivot on a solid bronze hub w three solid spokes. Each spoke is bigger in diameter than my thumb.

KFP talked me out of ordering a spare blade because they have only replaced ONE in over 10 years. Because it''s so easy to replace, the blade is designed to break before the bronze hub. (I wouldn''t want to be on a boat that hit anything hard enough to break that hub).

Most of their references were pretty long term (multiple years and several over 500 engine hours). I''ve had this one installed for a couple of months.

They were willing to send me jpg photos of a dis-assembled prop, and individual discussion about electrolysis, sizing, construction. Rather inventive those New Zealanders....

mcain 11-13-2003 06:36 AM

best folding prop?
 
Sorry to keep asking questions, but you have piqued my interest. I did see the previous post on perf improvements and they were impressive. Are the blades flat, like the maxprop, or have some curve to them like the autoprop? They have apparently stock sizes of 16" and 18", and somehow trim down to get other sizes--my prop is a 17"--do you have any idea who effective they are at getting 3 balanced blades while cutting them down?
And last (for now), can you easily adjust the pitch angle while the prop is in the water? This would be really nice all by itself, and is available on only very expensive models of adjustable pitch props. Of course, the autoprop just does its own pitch adjustment.
And where did you buy it from? Directly from Kiwi, or from a distributor--there are several in Australia or NZ who have web sites, with differing prices. Lowest I saw was about 1050 US$. Is shipping ridiculous in price and/or length of time to get it?
Thanks for the info.


paulmcquillan 11-13-2003 01:05 PM

best folding prop?
 
The exchange rates evened it out so much that I just bought if from NZ . Shipping included to any US address. (reached them through the Kiwi Props NA site.) Owner of Kiwi Props is John Blundell, on the North Island at blundell.family@xtra.co.nz.) Money back performance guarantee first 30 days

Mine was 17x22. Composite blades trim with a sharp knife (they did it !!!). Blades are Dupont Zytel. Tough stuff. Slight camber to blade edge to help maintain feathered attitude. Blades are thicker at the root, and have an angle from mid point to tip.

Delivery time is about 10 days after they get the spec sheet you fill out, via insured mail. May be longer if you don''t have an SAE taper shaft (outside US-Can).

Allen wrench to adjust pitch in or out of the water. They recomend a coat of ablative bottom paint on the prop.

Ours balances flawlessly, even Grandma Lynn can tell the difference when we are sailing. It''s smoother now at 2,400 than the fixed prop was at 1,800.


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