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Nibral vs Bronze

Discussion in 'Technical Discussion' started by Pascal, Nov 15, 2017.

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  1. Pascal

    Pascal Senior Member

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    getting conflicting feedback on the question

    Finally hauled out my 1970 53 Hatt MY for the repower and all the work needed out of the water. DD 8V71Ns and Allisons are coming out being replaced by 450hp fact reman C series Cummins with new shafts and new wheels (28x24 4 blades)

    Nibral wheels are about 25-30% more than plain bronze. I understand they're better for high HP application but I m just not sure they're worth it for 450hp and a 19/20kts boat.
  2. Capt Ralph

    Capt Ralph Senior Member

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    I've been thru this a couple of times. Stay with the bronze. Cheaper to fix also.
  3. captholli

    captholli Senior Member

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    Nibral or Nickle Bronze Aluminum wheels are 20 % harder and 15% lighter than Manganese or Bronze wheels. Their erosion and abrasion resistance is much higher than bronze , Blade section thickness is less due to hardness. Nibral is actually easier to weld and repair than manganese. I went through this scenario a few years ago replacing a very expensive pair of German Shaffran wheels. I cant say whether or not your application would benefit the extra expense of Nibral pound for pound .
  4. Silver Lining

    Silver Lining Member

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    Pascal I am not an expert by any means on propellers. However, the materials properties are that nibral is 25 percent higher tensile and yield strength and similarly better brinnell hardness. Nibral is 10 lighter (less dense) but 25 percent stronger. It is somewhat more weldable and will flex less under load which supposedly improves fuel efficiency. It is also suppose to have reduced wear from cavitation. With these advantages it appears to be a superior material for props and I would always use nibral on a planing boat.
  5. Capt Ralph

    Capt Ralph Senior Member

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    Seems a lot of things have changed.
    Well, I guess they have.
    There is only one prop shop left between Savannah and Orlando. He is in Brunswick.
    Before they closed, the last two shops in Jacksonville (Ellis & Jax Prop) Talked me out of Nibral stating is was more expensive to repair because it was more brittle.
    Years later and here, I'm reading something different.

    My ole bronze 32 x 32s are still going great that I purchased near 8 years ago. Probably like the operation that Pascal plans, we rarely go to the pins or fast cruise, but when we do, they preform well.
  6. Capt J

    Capt J Senior Member

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    What does your prop shop recommend? They would know the specs. Personally I would go with Nibral......but you might be able to find a good used set in that size.
  7. Pascal

    Pascal Senior Member

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    I havent talked to the prop shop yet but will. I m just trying to get real world feedback instead of just relying on a vendor. :)

    I understand the benefits of the material but not sure i woudlnt be an overkill in my application
  8. MBevins

    MBevins Member

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    My opinion is that if you are never going to push the boat above hull speed (or there abouts) there is no need to install the Nibral props. Nibral's main advantage is they don't flex under the loads of a planing hull. So if you're not going there then I don't see the added expense having any pay back.

    If you look at the trawler world they don't use Nibral's.
  9. Pascal

    Pascal Senior Member

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    I understand that. If i was keeping the old DDs or repowering with lower hp i would definitely be going for bronze. Since i am putting in 430hp C series and am putting the boat on a diet durign the refit using lighter material inside (hatteras loved 1 1/2" ply back in the 70s for interior work...) the target top speed is around 20 / 20.5 kts. 53s with the 430 DDs (about 3000lbs heavier inc the allisons) top around 18 to 19kts

    So bottom line, i wondering if more efficient Nibrals woould bring any benefits
  10. Capt J

    Capt J Senior Member

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    Nibrals have a lot more forgiveness if you get into sand. A set of props is going to be on the boat for decades, I wouldn't skimp to save a little money. Yes, if you're trying to get more speed then yes the nibrals will be faster, the regular bronze propellers WILL flex because of the weight of the Hatteras.....
  11. MBevins

    MBevins Member

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    In that case I would definitely go with the nibral's, that is a big heavy boat you're pushing.
  12. Pascal

    Pascal Senior Member

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    One of the prop shop and I m getting quotes from recommends bronze because of the low pitch (24")
  13. Capt J

    Capt J Senior Member

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    There is no negative to going with Nibral over Bronze, only positives, besides the price.
  14. Pascal

    Pascal Senior Member

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    Yeah well... its about $1000 extra per wheel :)
  15. Capt Ralph

    Capt Ralph Senior Member

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    How far off are your original wheels?
  16. Pascal

    Pascal Senior Member

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    I don't know and I don't care :). Getting new shafts and wheels. Will keep old ones as emergency spares :)
  17. PacBlue

    PacBlue Senior Member

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    For all powerboats , money spent on the propulsion system is money well spent. Think of it this way , that extra money is working for you every single rpm, and you rely on it to get yourself out of tight spots or back home. Spend good money on props, shafts, struts, cutlass bearings , etc. it will hold a better tolerance as a Class S propeller and give you back a smoother and better quality experience underway.
    Leave bronze for workboats that hit things underway and stick with NiBrAl Class S.
  18. Capt Ralph

    Capt Ralph Senior Member

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    I do await the results of Paccal's performance runs. I so wish he has a chance to compare both types of wheels.
    Years ago, prop shops had experimental props they would loan out. Wish a couple of sets were available now to compare.
  19. Pascal

    Pascal Senior Member

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    Update...

    I brought my set of spares to the prop shop and it turned out they were nibral and the right diameter. They were able to adjust the pitch although apparently its much harder to do that on nibral than bronze

    We splashed the boat a couple of days ago. Havent done a full sea trial yet but briefly ran her up to cruise rpm and got 17 knots, silky smooth. Will do a full sea trial with cummins mech in a couple of weeks when we come back from a trip to the exumas and will know then if we turn rated rpm...

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