Reduced Cavitation, High Efficiency Outboard Propulsors for Small Planing Craft

Discussion in 'Jet Drives' started by OCB, Aug 9, 2017.

  1. OCB
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    OCB Junior Member

    I'm looking for the company's that got this contract. Can anyone tell me who got them? I have a new impeller design.

    Thank you,

    OCB
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    What contract ?
     
  3. OCB
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    OCB Junior Member

    It was posted by Yellow jacket on this thread: Inline Outboard Jet, or outboard tunnel?
    This is being done by the U.S. Navy right now. There are three companies that were awarded contracts to develop a more efficient waterjet for the 55 hp heavy fuel outboard that is used by the special forces. The objective of the system is to be more efficient than conventional outboard jets as well as reduce the acoustic signature of the system compared to propellers or conventional outboard jets. Conventional outboard jets use a radial flow impeller that is mounted on the engine output shaft, then they collect the flow and spit it out the back. This results in a high speed impeller running at 5500 rpm and lot of noise as well as poor efficiency. The design goals for the replacement system are improved efficiency and reduced noise so that the Zodiac boats can be used for mine sweeping or mine laying, where sonar is required. The special forces use this boat and they need a system that has no prop hanging down under the boat. It is expected that the resulting systems would use a more conventional axial flow waterjet operating at lower rotational speeds. The program is an STTR effort that is being done with universities, and the program number is N17A-019. Here is a link to the solicitation. Reduced Cavitation, High Efficiency Outboard Propulsors for Small Planing Craft | SBIR.gov https://www.sbir.gov/sbirsearch/detail/1208623 There were three winners that were announced and work will commence on the program in June, so what you are talking about is most certainly feasible. If you look at the Mercury "Sportjet" drive, this is essentially an outboard motor sitting on a modified lower unit that is coupled to an axial watejet. While it's mounted inside the boat, there is nothing that says this couldn't be done on an outboard. The biggest issues will be ventilation and keeping the unit from sucking up air as you turn or go over wakes at speed.

    Reduced Cavitation, High Efficiency Outboard Propulsors for Small Planing Craft | SBIR.gov https://www.sbir.gov/sbirsearch/detail/1208623
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Ok, I remember that.
     
  5. johneck
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    johneck Senior Member

    Any progress with this?
     
  6. OCB
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    OCB Junior Member

    Yes I found Candent was one of the three company's that was awarded part of the 1st contract. I spoke with Cadet before they submitted for the 2nd part of the contract. They are working with Iowa University and former Rolls Royce jet engineer. I offered share our new tech for free, but they declined. They where awarded the 2nd part of the contract.
    I'm doing all our R&D in house on out board jets now.

    OCB
     
    Last edited: Dec 18, 2017
  7. Barry
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    Barry Senior Member

    fyi
    Your comment in a much earlier post suggests the "c0nventional jet" uses a radial impellor. This is incorrect. The impellor is an mixed flow impellor but the shape of the housing,
    if you are referring to the pump that most outboard OEMs use, looks similar to a centrifugal pump and build by Specialty Marine/Outboard Jets in California. A radial flow impellor has the inlet coming into the center area of the impellor, the water is accelerated radially to the edge of the pump housing then out to an outlet. Generally, centrifugal pumps are high pressure low volume. Mixed flow impellors, Berkley, American Turbine, medium volume medium pressure and then axial pumps, older Hamilton, Kodiak . (the new Hamiltons are said to be more axial in flow configuration)

    The mixed flow combines more radial flows from the shaft out with also a strong axial flow component.

    [​IMG]
    Centrifugal
    [​IMG]
    Axial
    [​IMG]
    Mixed
     
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  8. OCB
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    OCB Junior Member

    Barry: Not sure where i posted Conventional jet had a radial impeller, I'm sure your correct. I was also not correct when i said Candent had been awarded the contract. I was informed it's going to be awarded next year.

    OCB
     
    Last edited: Dec 24, 2017
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