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Bertram 42 Detroit 6v-92TA Repower with Yanmar or Cummins

Discussion in 'Bertram Yacht' started by etang789, Jul 5, 2017.

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  1. stuben, Dec 1, 2021
    #121
    stuben

    stuben New Member

    Joined:
    May 18, 2020
    Messages:
    1
    Location:
    Maine
    Regarding the AQ 22 high strength... Aqualoy (Western Branch Metals) offers "high strength" alloy down to 2 1/4", but this is nearly a marketing thing. It all comes down to the "torsional yield strength" and each individual shaft can be graded to find its torsion yield. 2" shafts have a minimum torsional shear yield of 70,000 psi but it is not uncommon to find a 2" shaft with an 80,000 or even 90,000 psi torsional yield which may solve the OP's issue. Here's an explanation of propeller shaft safety factors and a handy calculator.
    chesapeake46 likes this.
  2. etang789, Aug 3, 2022
    #122
    etang789

    etang789 Member

    Joined:
    Jul 5, 2017
    Messages:
    54
    Location:
    Hong Kong
    Heres some project updates!

    So the boat hit about 28knots with maximum throttle at 2700rpm using the old propellers 30x32 3 Blades. I believe changing them can get me better cruising and top speed.

    Redid the exhaust with new Centek 6" to 8" Fiberglass 45 Degree Elbow and Trident Hose / Clamps

    Finished the Interior finally! Tinted the windows with 3M PR40 ! And the rear bimini top!

    Installed new Victron Energy Battery Charger with Cerbo GX. Redid all the 12v wiring with correct marine grade wires and fuses, which the shipyard contractor cheaped out!

    Attached Files:

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