am looking for a new prop has anyone any exp. with the composite props from New Zealand, I think thats where their made, and I believe they make a folding one.
props
- Thread starter shugy
- Start date
- Status
Two seasons ago I fitted a Kiwi feathering prop to my H410.
http://www.kiwiprop.us/index.htm
I have been very pleased with all aspects of this equipment. My speed under power has improved significantly, and I think my drag under sail has been greatly reduced.
Maintenance is easy -- lube once a year at haulout - and it is easy to adjust the pitch yourself using a hex wrench, even if boat is in the water.
http://www.kiwiprop.us/index.htm
I have been very pleased with all aspects of this equipment. My speed under power has improved significantly, and I think my drag under sail has been greatly reduced.
Maintenance is easy -- lube once a year at haulout - and it is easy to adjust the pitch yourself using a hex wrench, even if boat is in the water.
Steve, I've had one for about 3-4 years on my H356. Very pleased with its performance, whether going forward or reverse. It is a feathering prop and under sail I have picked up at least if not better half knot of speed.
Going through the Dismal Swamp this last fall I hit a underwater tree limb and damaged two of the three props. Cost to replace was $100 a blade. After calling Kiwi I had the new blades in three days. Easy to replace and adjustment for pitch is also easy.
Going through the Dismal Swamp this last fall I hit a underwater tree limb and damaged two of the three props. Cost to replace was $100 a blade. After calling Kiwi I had the new blades in three days. Easy to replace and adjustment for pitch is also easy.
I was seriously looking into the KiwiP to replace my aged Martec folder. However, after discussions on another forum, I will be going over to a Flexofold 2 blade. (I have a Yanmar YSM 12 so I need all the efficiency I can get.)
I have no affiliations with Flexofold, just thinking that the reports are there that show efficiencies etc, and the cost for a two blade (they're all expensive!!!) is more attractive.
Here's a cut 'n paste from that discussion by the North American Flexofold sales rep:
" Clearly, I'm biased, but Nige's statement about motoring performance of feathering vs. folding is incorrect on several measures.
I see virtually no reason to choose a feathering prop unless your prop is in an aperture and a good folding prop won't fit. In the past year I've been to 5 major boat shows and spoken with hundreds of Flexofold owners. Very nearly every single one of them, when questioned about reverse performance say that their Flexofold (2-blade or 3-blade) offers the same or better performance in reverse compared to the fixed prop they replaced, in real world use. A Pearson 40 owner has told me that he can stop his boat from 6.5 knots in >1.5 boatlengths with his 3-blade Flexofold. A Hanse 630 can stop from 8 knots in 1 boatlength with our 4-blade. Most owners say they also have improved control in reverse due to a reduction in propwalk. The oft repeated myth of lousy reverse performance of folding props is true for makes, but not for all and certainly not for us in real world situations. It drives me nuts when I see an offhanded remark about folding props having lousy reverse performance. Independent testing shows our props give up a whopping 1 second of stopping time to most of the feathering props. That's just not terribly significant on the water.
Even if you don't believe any of the above, isn't like 99.5% of your motoring in forward? Most feathering props are inherently inefficient due to their flat blades. An efficient motoring prop should have constant pitch, with the blades angle of attack changing to correspond with the increase in rotational speed as you move out from the root of the blade to the tip. A well designed, efficient prop should also have a proper hydrofoil lift generating profile shape, with some ability to generate lift/suction on the forward side of the blade, as well as thrust on the aft side. A flat blade simply can't do those things, and as a result, is about 50% as efficient as a Flexofold at converting your engine's HP into actual forward thrust, according a the most scientific prop testing ever done (University of Berlin study, which I'm having trouble attaching).
Non-racers should be more concerned with the efficiency of their prop than racers, as they're more likely to spend more time motoring or motorsailing to a destination. Most of my customers report that they cruise at several hundred lower RPM at the same boatspeed. If you can cruise at less RPM less under power, at the same speed, you improve your fuel economy and range, right? At Strictly Sail Pacific recently, I had a Catalina 380 owner tell me his fuel consumption dropped by nearly 25% when he changed to a Flexofold. I was stunned, though it did make me wonder if he may may have bee a tad underpropped previously... That may be an extreme example of a common result. This stuff IS significant, particularly as you do more motoring as many non-racers tend to do.
Independent tests like this one by Yachting Monthly bear out what I'm saying. Flexofold beats Kiwi in 4 of 5 tests conducted. The Kiwi has marginally higher reverse thrust, but marginally worse stopping time- insignificant differences in reality. The Kiwi is notably worse in the forward tests, near the bottom in most tests, as are the other feathering props. Kiwi's more expensive than our 2-blade, but a few hundred bucks less than our 3. The other featherer's are more $.
Another real world difference which the tests don't talk about is the tendency to catch a crab/lobster pot line, loose netting, or kelp on the protruding blades of a feathering prop under sail, while a folding prop will more likely shed those things. I've heard a few interesting stories about that!
Sorry, i didn't mean to get so salesy (and yes, I did buy an ad!), but reading a blanket statement about feathering vs. folding that simply isn't borne out by test results got me going! Yeah, I do want to sell my product, but I as a long-time SA'er, I'm not afraid to call "bullshit" and debunk myths.
The great thing is, everyone gets to vote with your wallet -there are an awful lot of choices for low-drag props, but Flexofold is the best!"
http://www.flexofold.com/
- Status