Rim drive propellers/ pods drives

Discussion in 'Props' started by OCB, Oct 22, 2016.

  1. OCB
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    OCB Junior Member

    Is there shaft driven rim drive propellers? Are there any company's in the US making rim drives? I been reading rim drive don't preform well at high speeds.
    I also was reading about pods and there claims of 15% + gain over inboard? Is this due to no rudder and parallel propeller to hull?

    Thank you in advance,


    OCB
     
  2. gonzo
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    gonzo Senior Member

    The pods like VolvoPenta have the propellers facing forward, which results in better performance.
     
  3. mydauphin
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    mydauphin Senior Member

    Yes shafts get in the way of water flow, but they also help protect propeller. You loss some power by necessary angling of props on regulasr shafts, but you also lose some power in forward facing props by extra gearing required. Also, I would not want to be a manatee around those giant egg beaters.
     
  4. powerabout
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    powerabout Senior Member

    how is there extra gearing in a pod when the prop faces forward rather than backwards
     
  5. mydauphin
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    mydauphin Senior Member

    Same amount, comparing pods vs straight shaft. Outboards and inboard/outboards suffer from same power loss. It is considerable if your talking larger hp and torque. Big ships with pods solve the problem by putting motor in with the pod so it is a straight shaft.

    A bigger issue is that of clean water. Unless you are running surface piercing or ventilated props you want your props as deep as possible. The forward facing props work well here.

    There is another issue I just remembered, tracking I think it is called. I piloted a 57 foot Hatteras that was extended but her props were not moved back to the stern. The boat was very hard to keep going straight. It required far more adjustment. Of course that may not be an issue with modern system with electronics.

    The modern forward facing prop system is not as simple as it may seem, they require the right hull, placement and modeling all via computers. Otherwise I don't they would work correctly if you just slap it on.
     
  6. mydauphin
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    mydauphin Senior Member

    Btw. Pods get rid of rudders and struts, there is your performance gain. Bit outboards and arnesons do the same thing
     
  7. WestVanHan
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    WestVanHan Not a Senior Member

    IPS=solution to a problem that doesn't exist

    They're not the best thing in my locale.
    With all the debris in the water plus uncharted rocks I know of incidents of bent props and wrecked units.... in the middle of nowhere. Glitches that had the pods facing in different directions.

    I was in FLA a couple years ago and towed a guy in,crying as he had pranged a reef and banged the IPS and couldn't afford it.

    Have read articles and tests and they state it's hard to tell if there is any efficiency gains.
    The basic yearly maintenance costs are several orders of magnitude higher,I've read recommendations for a twice yearly haul out to check the seals.
    Seals always go and it's a $7k-10k job per side IIRC. It's not just an oil change...
    Another where the bearings went as well-due to water-and it was a $20k job.


    Any fuel economy gain will be negated to an impressive-and depressing/bank account depleting-amount. All you need to do is google "IPS problems"

    No Thanks.
     
    Last edited: Oct 23, 2016
  8. powerabout
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    powerabout Senior Member

    yep I knew a captain running twin ips in Singapore, every trip out they had bent blades
     
  9. powerabout
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    powerabout Senior Member

    I think the bigger gain is the thrust in in the direction you are going hence a inboard is always slower then the same engine as a sterndrive even given the drive train changing direction twice.
     
  10. mydauphin
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    mydauphin Senior Member

    The bigger the boat the more inboards make sense. I have basically divide it at 30 feet, below it go outboards, above it some kind of inboard straight shaft.

    On IPS costs.... hitting a rock etc... with a regular shaft can be very expensive. shaft, struts and props. You can spend $1-$80k depending on damaged. On an IPS the costs are higher, considerably higher. I have heard over 100k even for a small repair. The IPS are designed to drop the pod in case of a hit, which kind omake sense. That way boat wont sink, boat it also means you will probably lose it.
     
  11. powerabout
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    powerabout Senior Member

    all true
    to me the secret will be a drop thru pod as currently if you hit something with an ips you usually sink
    Try to find as delivery captain who will deliver one in asia..not!
     
  12. mydauphin
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    mydauphin Senior Member

    I have a feeling that a lot fo people that design this stuff are aerospace engineers that have never owned a boat. How many of us have hit a rock, bent a prop, taken it out and hammered it into usefulness then gone on to port. I am sure not many, but it happens and part of the boating life. Seatow can only take you so far.
     
  13. brian eiland
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    brian eiland Senior Member

    Bit of a conflicting statement. If a unit is rim driven then that necessarily means it is not shaft driven. The prop is either shaft driven or rim driven.

    To my knowledge there are NO manufactures doing rim-drive in the USA. And there are only a few in Europe. Its a young technology that has not been worked on in earnest over the past 6 years ever since the big downturn in the boar market due to the economic crash of 2008-09.

    Hopefully we will see some major new developments. i was hoping to install some higher power, retractable units on this design:
    http://www.runningtideyachts.com/dynarig/

    http://www.runningtideyachts.com/dynarig/Section_8_and_Rim_Drives.php

    One of the more viable production units (small HP) is this Vetus model
    https://www.youtube.com/watch?v=Iewz5lDbXeQ
     
  14. OCB
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    OCB Junior Member

    Postings w

    Well said!

    I want to thank Everyone for the great input!

    OCB
     

  15. OCB
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    OCB Junior Member

    Rim drive propeller with shaft drive?

    I like the retractable drive design when needed. I have seen other post of yours on new propulsion ideas. I don't want to hijack anyone's thread with my designs ideas.
    I'm trying some new things in the drive design. I will build what I think is the best drives for my needs. I like to build things that are simple to service. Sometimes people have a problems seeing the light with new designs. It's to big of gamble for company's to use anything new before it's fully proven. Also helps if it works better and cost same less to upset the current market.
    I'm working on a prototype rim driven propeller. I will use a shaft to drive the outside rim of the unit. I was thinking if it had no hub, it was a rim drive? I have been wrong before?
    IMHO Simple designs like shaft drive are not done yet!

    OCB
     
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