Click for Nordhavn Click for Northern Lights Click for Mulder Click for Delta Click for Abeking

Question about Bertram 46.6 propeller

Discussion in 'Bertram Yacht' started by ARIONZLA, Nov 22, 2013.

You need to be registered and signed in to view this content.
  1. ARIONZLA

    ARIONZLA New Member

    Joined:
    Nov 22, 2013
    Messages:
    1
    Location:
    Puerto La Cruz
    I have a Betram 46.6 with a couple of Detroit Diesel 8v71 turbo and i just can reach 18knts at 2150rpm.(max rpm LOADED) ( MAX. RPM "empty" 2600)
    I have a 28x34 propellers. Is this propeller's size correct to develop a 22knts cruise speed or do i have to change these propellers?
    which one is the size recommended in this case?
  2. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,647
    Location:
    Satsuma, FL
    Man, What are you loading her with, My second wife and her family?

    OK, real questions;
    How long have you owned her? Same performance since? Any history or logs from previous owners? I assume 3 blade wheels. Condition of bottom, tab position & bow angle? Color of exhaust thru-out rpm range and do you have fuel flow meters? Does both the engines reach these same rpms?
    Last engine survey or tach verification? Winning Florida lotto numbers for tomorrows drawing.

    ,rc
  3. RER

    RER Senior Member

    Joined:
    Jan 20, 2009
    Messages:
    1,532
    Location:
    Newport Beach CA
    That's a lot of pitch - I think 28x32 is closer to spec. Perfect would get 2450 unloaded, 2350 loaded but I don't expect perfect from old boats. Your unloaded RPM is too high. Are you going off VDO tachs? If so you need to shoot the motors with a gun to confirm RPM. How heavy are you (tower?) and what's the condition of the motors - how much is left of the 435hp those 8V71's started out with. As far as cruising that old girl at 22 knots - I don't think that's realistic.
  4. Good grief

    Good grief New Member

    Joined:
    Oct 20, 2023
    Messages:
    5
    Location:
    Massachusetts
    My 1973 46 foot bertram with full tuna tower cruises easily at 22 knots using
    Gori stainless 4 bladed props. I have 2 sets and would be willing to sell one pair. My boat has 2 inch shafts. Allison m20 gears. That would be with full fuel and water and Kohler 12.5 kw gen set.
  5. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,647
    Location:
    Satsuma, FL
    Not a record, but you are selling to a 10 year old thread.
  6. Good grief

    Good grief New Member

    Joined:
    Oct 20, 2023
    Messages:
    5
    Location:
    Massachusetts
    Guess i got carried away when i saw the 3. Still factual however.
  7. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    12,647
    Location:
    Satsuma, FL
    Welcome to Yacht Forums.
    Maybe an ad in the sale/trade thread would bring better response.
    Lots of Bertram fans here. After near 20 years, recently moved off of our Bert MY.
    <-----
    Look forward to read of your Bertram projects and adventures.
  8. mapism

    mapism Senior Member

    Joined:
    Aug 9, 2008
    Messages:
    2,111
    Location:
    Sardinia
    If you already mentioned that, I missed it. How come?
    I hope that's not for health reasons, as it just happened to a boating mate of mine.
  9. Good grief

    Good grief New Member

    Joined:
    Oct 20, 2023
    Messages:
    5
    Location:
    Massachusetts
    We just donated our pristine 1973 bertram sport fish, all remodeled because we tried all summer to sell it. After an offer of 10k i finally said thats it. No more stupid tire kickers trying to take me for a ride. Purchased it in 1987 and it served us well. Bittersweet but at 81 it was time. Great memories. Great boat. The spare props are in the basement. Seems a shame to scrap them
  10. Nkiki2000

    Nkiki2000 New Member

    Joined:
    Dec 17, 2023
    Messages:
    1
    Location:
    Northport ny
    Do you still have the props? I’m wondering what size they are. I may be interested in the pair as well
  11. Good grief

    Good grief New Member

    Joined:
    Oct 20, 2023
    Messages:
    5
    Location:
    Massachusetts
    Sorry 3 bladed are 28+33 and stainless are 30+32
  12. Good grief

    Good grief New Member

    Joined:
    Oct 20, 2023
    Messages:
    5
    Location:
    Massachusetts
    Email address removed I have pictures
    Last edited by a moderator: Jan 15, 2024