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  1. #1
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    Variable Pitch Props

    I remember Land & Sea and Quicksilver both made a variable pitch prop.

    Seems like a really good idea.

    Why don't I see them around much?

    Which one is considered better?

    Does a vented prop achieve about the same thing?

  2. #2
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    There was a brand called Aerostar and they were the Cadillac of variable pitch props. I have owned two of them and they flat ass worked. They were not designed to be surfaced but when ran submerged they were they best available. They usually had five inches of pitch change. One of their models was called the Switchblade.

    Carter Powell

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  4. #3
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    The Land & Sea aren't very "durable" on hi-perf boats, especially when "surfaced". I have a couple of them in various states of disrepair.

    https://www.screamandfly.com/showthr...44#post3152344

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  6. #4
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    Quote Originally Posted by Carter Powell View Post
    There was a brand called Aerostar and they were the Cadillac of variable pitch props. I have owned two of them and they flat ass worked. They were not designed to be surfaced but when ran submerged they were they best available. They usually had five inches of pitch change. One of their models was called the Switchblade.

    Carter Powell
    Ah, yes, I remember now, there was Aerostar too. Since they seemed work, I wonder if it was pricing that killed them

  7. #5
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    Maybe they didn't survive, but I still think they were a good idea and were innovative. Think I got this right:

    L&S - worked on springs and cams, and needed to be beefed up so it didn't fall apart, especially when surfaced.
    Aerostar - worked really well, except when surfaced. Very expensive as I recall. No springs, but I forget how this worked.
    Quicksilver - Have not heard much about this one. I have seen one though. As I recall it worked on weights and was really heavy.

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    The L&S "barrel" is aluminum with Nyliner-type bushing inserts to support the blades. When the bushings wore out or failed the holes in the barrel/body got damaged. Also, the little cams would probably have lasted longer running in oil than water.

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  10. #7
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    Quote Originally Posted by David - WI View Post
    The L&S "barrel" is aluminum with Nyliner-type bushing inserts to support the blades. When the bushings wore out or failed the holes in the barrel/body got damaged. Also, the little cams would probably have lasted longer running in oil than water.
    Interesting ...and any idea specifically what the issue was when surfacing them.? Like did the blades pop out or something like that?

  11. #8
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    The barrel broke on my L&S Torqueshift, and yes I surfaced it. They replace it under warranty. I stopped using it as I thought it was contributing to my XR4 gearcase destruction. The acceleration was great fun.

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    Quote Originally Posted by David View Post
    The barrel broke on my L&S Torqueshift, and yes I surfaced it. They replace it under warranty. I stopped using it as I thought it was contributing to my XR4 gearcase destruction. The acceleration was great fun.
    Sounds like a few more years of development would have made it quite a product. You know who owns the patent?

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    Quote Originally Posted by Glastron1987 View Post
    Interesting ...and any idea specifically what the issue was when surfacing them.? Like did the blades pop out or something like that?
    They would fling the blades off. If I get a chance I'll take a picture... the blades are on (probably) about a 1" shaft.

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  15. #11
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    One of my boats is a 1989 Glastron CSS16 (like an older CVX-16) with an 80hp merc 3-cylinder on it. Top speed is about 40mph which is fine for lots of fun, except when you try getting up on one ski. I tried this past year and ended up drinking more than my share of the lake. One of those variable pitch props would be a big boost in capability for a rig like that.

    In the meantime, I happen to have picked up a Mariner 175-Ski motor (V-6) that I'm planning to put on next summer. That should liven up the whole shot.

  16. #12
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    It's possible that with better metallurgy (stainless steel hub?) and some FEA work, the Land & Sea design could work. The design is more than 20 years old, so the patent would have expired. I doubt the few remaining small prop shops would have the resources to do the development.

  17. #13
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    Quote Originally Posted by David View Post
    It's possible that with better metallurgy (stainless steel hub?) and some FEA work, the Land & Sea design could work. The design is more than 20 years old, so the patent would have expired. I doubt the few remaining small prop shops would have the resources to do the development.
    Wow, I understood the stainless-steel part of that but had no idea what FEA was. I had to look that up. Seems like surfacing it at a high RPM would be an alternative to that

  18. #14
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    FEA = Finite Element Analysis. A part, say a propeller hub, is mathematically modeled as a huge number of tiny parts that mesh together. The stresses on each part, aka element, are calculated. The software can be purchased reasonably cheaply, but the experience to do a good job with it helps. It would start with estimating the loads that the propeller blades put on the hub. LOL, another FEA model.

    FEA is really cool. You get a computer screen showing different stress levels in a part as different colors. OF course one still needs to test to validate the model, but it my pre retirement world, FEA greatly reduced the design/test/break/redesign loops.

    https://www.autodesk.com/solutions/s...afa89c6b4968de

  19. #15
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    Quote Originally Posted by David View Post
    FEA = Finite Element Analysis. A part, say a propeller hub, is mathematically modeled as a huge number of tiny parts that mesh together. The stresses on each part, aka element, are calculated. The software can be purchased reasonably cheaply, but the experience to do a good job with it helps. It would start with estimating the loads that the propeller blades put on the hub. LOL, another FEA model.

    FEA is really cool. You get a computer screen showing different stress levels in a part as different colors. OF course one still needs to test to validate the model, but it my pre retirement world, FEA greatly reduced the design/test/break/redesign loops.

    https://www.autodesk.com/solutions/s...afa89c6b4968de
    Good to know in case of redesigning the prop

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