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Thread: Prop Comparisons

  1. #16
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    Capt. Ron is spot on here. I did choose the Max prop mainly based on a longstanding reputation and lack of bad comments. Also that the company has been around for a long time and hopefully will continue to support their products. I picked up just over 1/2 of a knot sailing verses the fixed three blade so that over a 24 hour period is 12 miles? Probably not that big of a deal on a 2 or 3 day cruise. Overall I have no buyers remorse on the max prop and will certainly put one on my next boat...

  2. #17
    Contributing Partner Chris A.'s Avatar
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    I could go for that...

    I could go for that 1/2 knot of sailing speed!
    Chris on Peregrine
    1987 E34 #247 Universal M25XP
    Portland, ME

  3. #18
    Principal Partner treilley's Avatar
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    As Chris said, I am very happy with the sailing and motoring performance of my flexOfold. Chuck Angle is the US rep in Marblehead, MA. Very nice and knowledgable guy. Deffinitely worth speaking to about props.
    Tim R.
    Living aboard in Portland, Maine
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  4. #19
    Principal Partner EGregerson's Avatar
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    prop shop

    when you're contemplating swapping around props, do you usually stay with the original diameter? e.g. i have (probably the original) 15 x 11 2 blade on my e34. if i went to a 3 blade, should i stay at 15; or can i drop to a 14"?
    Valinor 1987 E34 Hull#243 2005 Volvo Penta D1-30

  5. #20
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    If you went from a 2 to a 3 blade, all else equal, you would go to a smaller diameter. Here's a nice little prop 101 write-up from a place that did a shaft for me a ways back:

    http://a1discountprop.com/propinfo.htm
    -David
    Independence 31
    Emerald

  6. #21
    Senior Moderator Loren Beach's Avatar
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    Lightbulb Prop Results

    New prop on yesterday. Michigan "Sailor" three blade. 15 X 10.
    Motored back to the moorage and evaluated it some on the way.
    The old 15 inch two-blade Autostream is off the boat for the first time since '95. (I had forgotten just how heavy that mechanism is!)

    Backing up is comparable but there seems to be a bit more walk to port in reverse. Something to cope with.
    Forward it obviously moves a lot more water with all that extra blade area.

    The propeller shop that sold it went by their own knowledge base and a modern computer application that compares hull characteristics and engine specs.
    Result is that they are close enough for now, but I can see that a future haul out will involve some slight re-pitching.
    Reason is that I can now only get about 2750 rpm in smooth water, for about 7.2 kts speed.

    With the former adjustable two blade I could get the full 2950 (+ or -) rpms at that speed.
    Now, cruise speed at 2500 is about 6.5. That's a bit high for smooth water motoring, and we will therefore have less HP available to punch through a head sea.
    This is far better than the 15 X 12 two blade that came from the first owner -- that prop hobbled my top rpm to about 2600.

    I imagine that reducing the pitch about an inch to 15 X 9 might about do the trick. But what would I know?

    Anyhow, that's where we are right now.

    Regards,
    Loren

    ps: see attached pics of new and old prop and Autostream hub before removal.
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    Last edited by Loren Beach; 05-19-2009 at 04:53 PM.
    1988 Olson 34 #8
    Sail # 28400
    Betamarine 25 (new 2018)
    Fresh Air
    Portland, OR USA

  7. #22
    Principal Partner EGregerson's Avatar
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    vibration

    loren ; since you didn't mention vibration, can i assume that the new prop is satisfactory? and ... how can you know what you gain or loose under sail with drag?
    Valinor 1987 E34 Hull#243 2005 Volvo Penta D1-30

  8. #23
    Senior Moderator Loren Beach's Avatar
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    Quote Originally Posted by EGregerson View Post
    since you didn't mention vibration, can i assume that the new prop is satisfactory? and ... how can you know what you gain or loose under sail with drag?
    It seems to be quieter, but that was only on a 40 minute trip back to the moorage. We plan to get out for a night or two this coming weekend and really get better acquainted with it. Sailing drag expected be about a half knot loss in light air, going by past experiences. Only time will tell, as the trite saying goes.


    Loren

    ps: here is another three-blade prop thread on this site:
    http://www.ericsonyachts.org/infoexc...ead.php?t=1106
    Last edited by Loren Beach; 05-24-2009 at 04:44 PM. Reason: add link
    1988 Olson 34 #8
    Sail # 28400
    Betamarine 25 (new 2018)
    Fresh Air
    Portland, OR USA

  9. #24
    Principal Partner u079721's Avatar
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    Quote Originally Posted by EGregerson View Post
    when you're contemplating swapping around props, do you usually stay with the original diameter? e.g. i have (probably the original) 15 x 11 2 blade on my e34. if i went to a 3 blade, should i stay at 15; or can i drop to a 14"?

    I guess I would disagree with David's comment above about "necessarily" going with a smaller diameter. Yes you CAN go smaller when you go from two to three blades, but you don't have to. What you do have to do is balance the load - meaning that if you keep the same diameter, and move from two to three blades, you have to drop the pitch. Or you can drop down in diameter an inch, and drop the pitch slightly less. Remember that after the switch you need to run the engine tests to see whether you are possibly over or under propped.

    In our case the PO went from a two blade 16" diameter 13" pitch fixed prop, to a three blade 16" diameter Max prop. Which was great, except that the yard pitched the prop at the same 13", which WAY overloaded the engine, and we could not get the rpms above 2000. Over the course of a couple of seasons we dropped the pitch all the way to 10", and finally got the engine revs back up to 2900.

    If he had gone instead with a 15" diameter prop we would probably have settled at 11" of pitch.
    Steve Christensen
    Twin Cities, MN
    Former Owner of Rag Doll
    1989 Ericson 38-200
    Hull Number: ERY38318C989
    Universal M40

  10. #25
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    Quote Originally Posted by Emerald View Post
    If you went from a 2 to a 3 blade, all else equal, you would go to a smaller diameter. Here's a nice little prop 101 write-up from a place that did a shaft for me a ways back:

    http://a1discountprop.com/propinfo.htm
    This is why I put in the key words "all else equal" and included the link to the prop 101 write-up. There are a LOT of variables here, and it can get very confusing to sort through. For example, depending on original tip clearance, you may or may not want to go smaller for other reasons, and this is where having someone who's got experience with your exact setup is a great time saver. I was lucky with Emerald in that someone else had already gone through all the headaches on the Independence 31 and my exact engine/transmission combination (thanks Glyn!), and the "right" prop was actually very different from the computer selected prop
    -David
    Independence 31
    Emerald

  11. #26
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    Prop Comparison

    In searching through my hard drive I came across an old XL spreadsheet that had the results of some tests run in Germany on several brands of folding/feathering propellers that I thought was interesting. Don't ask me what some of the symbols and measurements are, I just don't know. Also I don't know how old this data is.


    http://members.toast.net/captron/propellor_test.htm



    Capt Ron
    E-38 Kismet
    Auburndale, Florida
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  12. #27
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    New Prop Purchase

    We just purchased Flexofold 2 blade 15x10 for our '87 32-3. The thing is in the mail and hopefully will be installed this weekend. I'll add feedback next week after we get her in the water. Called Chuck Angle in Ma. and he was very helpful. 1095.00 plus shipping. We currently have a 14x9 3 blade fixed. After reading the May issue of Yachting Monthly and discovering the drag characteristics, we elected to make this change for racing purposes. We always back in to our slip. Should be interesting.......

  13. #28
    1984 Ericson 30+, Nanaimo, BC
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    We have a 13 x 9 Varifold folding propeller on our 1984 E30+. It generally works well. Although there is no tach on the boat, I try to run the engine at about 80% of top speed judging by sound/feel. At that rate, the boat will easily cruise at 6.2 knots, and I can run it at up to about 6.8 at full throttle, though I don't do this for long.

    The boat operates well in forward, but less well in reverse, with some prop walk, especially initially. Once I get underway in reverse it's not bad.

    The folding prop was new in 2005. It sometimes stiffens up a bit due to marine growth, so won't open/close as freely. But working it by hand occasionally does free it up, and a good cleaning/scraping of the gears when hauled gets it operating like new again.

    As it's the only prop that has been on this boat since we bought it, I don't know how it operates with another prop.

    Frank

  14. #29
    Senior Moderator Loren Beach's Avatar
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    Lightbulb Further in-use report

    Just got back home from a couple weeks cruising.
    Everyone said that a three blade (any kind) would vibrate less than a two blade. Except for a persistent and attention-getting vibration at around 1200 to 1400, this appears to be so. Not really a lot of difference that I can see, though.
    Power (i.e. thrust) is noticeably better at all rpm's than the old two blade. To be accurate, this is not really a fair comparison, since there is no cupping on the former feathering prop blades.

    Reverse is less effective, with more prop walk.

    The boat is a better motor boat now and also a better motor sailor...

    Under sail, in the lower river/bay closer to the ocean, with the afternoon winds hitting 25+ true, we could only make low 8's and spent most of the time in the high 7's, broad reaching.
    With our feathering prop, same conditions, we were always in the high 8's and low 9's.
    While the dock gossip is that a fixed blade drags the most in light air, I am now of the opinion that it also costs up to a knot in medium and heavy air as well. (Of course, that opinion is still only worth about two cents.)

    Admittedly, what with light winds on the nose all the way down the river to Astoria, we motored like a trawler! Covered ground at a faster pace than in the past.

    Obviously there were bound to be plusses and minuses to this prop change over...


    Our thinking now is to start budgeting for a three blade feathering prop someday.

    And that's my report.

    Cheers,
    Loren
    Last edited by Loren Beach; 07-05-2011 at 02:22 PM.
    1988 Olson 34 #8
    Sail # 28400
    Betamarine 25 (new 2018)
    Fresh Air
    Portland, OR USA

  15. #30
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    Hi Loren,

    this is very interesting feedback on your top speeds with the prop switch. Really makes me wonder about the 3 blade bucket I am dragging. In the interest of looking at all factors, any chance that you've got bottom fouling that could be part of the speed change? I know we have different fouling issues on the Chesapeake, but I've always been amazed how quickly we get slime build up and how much it affects speed (and it's not just me, pretty much all the boats at our marina have constant battles with this from what I can tell).
    -David
    Independence 31
    Emerald

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