Propulsion

Discuss marine engines, drives, and propulsion systems.

  1. Props

    Propeller selection, performance comparison, prediction, experience, and modification.
    Discussions:
    543
    Messages:
    6,440
    Latest: The mystery of a proper prop and terrible performance sdowney717, Jul 22, 2025
    RSS

  2. Surface Drives

    Surface Drives. Arneson, BPM, Seafury, PSI, Levi, Etc.
    Discussions:
    185
    Messages:
    2,862
    Latest: Is Levi Drives still in business? BlueBell, May 30, 2025
    RSS

  3. Jet Drives

    Jet Drives (pumps, impellers, etc.)
    Discussions:
    464
    Messages:
    4,474
    Latest: Affordable Water Jets? RSD, Sep 1, 2025
    RSS

  4. Outboards

    2-stroke and 4-stroke outboard motors.
    Discussions:
    1,049
    Messages:
    10,172
    Latest: Yamaha 5BS L661 Owners/Repair Manual Padmack, Nov 8, 2025
    RSS

  5. Sterndrives

    Stern drive lower and upper units, transom and gimbal assemblies, steering, and trim pumps. Mercruiser (Alpha One, Alpha One Generation II, Alpha SS, Bravo One, Bravo Two, Bravo Three, Bravo XR Sportmaster, TRS, Speed Master), IMCO, ILMOR, Konrad, OMC, Volvo Penta
    Discussions:
    552
    Messages:
    3,882
    Latest: Mercruiser Alpha 1 gen 2 gonzo, Oct 11, 2025
    RSS

  6. Pod Drives

    Volvo IPS, ZF, CMD Zeus, and other pod-drive systems
    Discussions:
    29
    Messages:
    299
    Latest: 50-200 hp electric pod with nozzle and motor on hub? ram68ocean, Jul 5, 2021
    RSS

  7. Inboards

    Inboard and Vee-drive hardware: struts, stuffing boxes, transmissions, coolers
    Discussions:
    540
    Messages:
    5,022
    Latest: Best practices for propeller shaft installation? Mark Willoughby, Oct 20, 2025
    RSS

  8. Diesel Engines

    Diesel Engines
    Discussions:
    692
    Messages:
    8,642
    Latest: Problem with Yanmar 2QM15 gonzo, Oct 14, 2025
    RSS

  9. Gas Engines

    Gasoline Engines
    Discussions:
    423
    Messages:
    4,652
    Latest: Anyone need a torque monster 383 SBC? gonzo, Sep 24, 2024
    RSS

  10. Electric Propulsion

    Electric propulsion systems
    Discussions:
    110
    Messages:
    2,187
    Latest: cheap electric motor with remote control CocoonCruisers, Nov 14, 2025 at 2:20 PM
    RSS

  11. Hybrid

    Hybrid propulsion such as diesel electric, hydraulic.
    Discussions:
    211
    Messages:
    5,275
    Latest: Hydraulic Drive for max efficiency Rumars, May 6, 2025
    RSS

  12. DIY Marinizing

    A forum to discuss "do it yourself" marinizing of engines / conversion of automotive engines to marine use.
    Discussions:
    276
    Messages:
    5,578
    Latest: VW/AUDI 3.0TDI marinising Radu Druncea, Jul 2, 2025
    RSS
Page 1 of 25
Sort By:
Title Start Date
Replies ↓ Views
Last Message
  1. Guest625101138

    DDWFTTW - Directly Downwind Faster Than The Wind

    Guest625101138, Jan 4, 2009 ... 38 39 40
    Replies:
    588
    Views:
    152,933
    gonzo
    Oct 4, 2021
  2. Guillermo

    New propulsion sytems for ships

    Guillermo, Dec 2, 2005 ... 37 38 39
    Replies:
    579
    Views:
    201,218
    fredrosse
    Oct 8, 2023
  3. SudorracMechEng

    wiggle drive propulsion application

    SudorracMechEng, May 7, 2012 ... 19 20 21
    Replies:
    304
    Views:
    60,851
    swashdrive
    Aug 17, 2012
  4. brian eiland

    Gas from Water, (WaterFuel), HHO technology

    brian eiland, May 15, 2006 ... 17 18 19
    Replies:
    278
    Views:
    83,190
    masrapido
    Apr 2, 2014
  5. tom kane

    Define what a Surface-Piercing propeller is

    tom kane, Jul 12, 2009 ... 13 14 15
    Replies:
    212
    Views:
    87,488
    tom kane
    Feb 18, 2021
  6. CatBuilder

    Ganging Outboards - Does it work?

    CatBuilder, Jan 14, 2012 ... 11 12 13
    Replies:
    183
    Views:
    42,876
    DCockey
    Jul 19, 2013
  7. Fanie

    Continuously Variable Transmissions

    Fanie, Jul 30, 2009 ... 10 11 12
    Replies:
    166
    Views:
    42,049
    BATAAN
    Jan 12, 2012
  8. Boston

    these turbine alternaters are easy to make

    Boston, Apr 1, 2009 ... 8 9 10
    Replies:
    143
    Views:
    34,017
    Boston
    Nov 16, 2010
  9. kistinie

    CPP desapear from recreational boats Who gets the benefit of the crime ?

    kistinie, Apr 4, 2009 ... 7 8 9
    Replies:
    133
    Views:
    25,952
    Landlubber
    Jun 10, 2009
  10. brian eiland

    Liquid Air Engine

    brian eiland, Jan 25, 2012 ... 7 8 9
    Replies:
    121
    Views:
    31,412
    RonL
    Aug 1, 2012
  11. Filmdaddy

    Auto Diesel (Yeah, again, but...)

    Filmdaddy, Jul 21, 2005 ... 6 7 8
    Replies:
    112
    Views:
    25,585
    FAST FRED
    Sep 4, 2005
  12. brian eiland

    in-line 6 Cylinder Engines, 'straight-six'

    brian eiland, Jun 26, 2012 ... 6 7 8
    Replies:
    111
    Views:
    64,828
    Frosty
    Oct 11, 2012
  13. ldrumond

    Use pressurized water as manuevering thruster?

    ldrumond, Jun 18, 2006 ... 6 7 8
    Replies:
    109
    Views:
    47,764
    SeaJay
    Aug 8, 2009
  14. marshmat

    Emission Controls - Technical Thread

    marshmat, May 23, 2009 ... 6 7 8
    Replies:
    105
    Views:
    19,844
    powerabout
    Dec 2, 2009
  15. xxdroom

    paddlewheeler recuction drive

    xxdroom, Oct 30, 2014 ... 5 6 7
    Replies:
    104
    Views:
    24,650
    JSL
    Jul 11, 2015
  16. DennisRB

    Diesel VS 4 stroke outboard fuel consumption

    DennisRB, Jul 20, 2010 ... 5 6 7
    Replies:
    100
    Views:
    43,966
    FAST FRED
    Sep 24, 2010
  17. brian eiland

    Exciting New EPS Thruster (& Propulsion)

    brian eiland, Nov 16, 2005 ... 4 5 6
    Replies:
    86
    Views:
    110,444
    johnnydfred
    Jan 9, 2025
  18. Canada Bob

    How much Push or Pull do you need ?

    Canada Bob, Dec 22, 2011 ... 4 5 6
    Replies:
    81
    Views:
    27,164
    hoytedow
    Dec 30, 2011
  19. Boston

    the steamless steam engine

    Boston, Apr 30, 2009 ... 3 4 5
    Replies:
    73
    Views:
    33,439
    cthippo
    Feb 8, 2011
  20. brian eiland

    FLYWHEEL Energy Storage Systems

    brian eiland, Apr 21, 2010 ... 3 4 5
    Replies:
    69
    Views:
    42,631
    brian eiland
    Nov 16, 2020
  21. watchkeeper

    Engine mount failures

    watchkeeper, Jul 19, 2011 ... 3 4 5
    Replies:
    66
    Views:
    20,480
    powerabout
    Sep 28, 2011
  22. CatBuilder
    Locked

    Brainstorming Retractable Drives

    CatBuilder, Sep 29, 2011 ... 3 4 5
    Replies:
    64
    Views:
    30,922
    brian eiland
    Jul 29, 2012
  23. Boston

    Most economical diesel

    Boston, Jul 9, 2010 ... 3 4 5
    Replies:
    64
    Views:
    16,512
    goodwilltoall
    Dec 16, 2010
  24. Jet_Love

    4 Stroke Cleaner Than 2, Really?

    Jet_Love, Jun 17, 2013 ... 3 4 5
    Replies:
    60
    Views:
    15,182
    FAST FRED
    Feb 11, 2014
  25. Ol Gillnetter

    Keel Modification

    Ol Gillnetter, Jan 24, 2013 ... 2 3 4
    Replies:
    59
    Views:
    17,147
    Ol Gillnetter
    Aug 22, 2014
  26. CatBuilder

    How Much Does it Cost to Marinize a Kubota?

    CatBuilder, Feb 3, 2012 ... 2 3 4
    Replies:
    57
    Views:
    36,800
    FAST FRED
    Feb 29, 2012
  27. Boston

    used motor oil as fuel

    Boston, Feb 5, 2012 ... 2 3 4
    Replies:
    53
    Views:
    11,685
    Boston
    Mar 2, 2012
  28. dskira

    Gas turbine

    dskira, Dec 14, 2009 ... 2 3 4
    Replies:
    53
    Views:
    24,644
    apex1
    Jan 3, 2010
  29. ChillrMn1

    Quadrajet Adjustment

    ChillrMn1, Dec 8, 2004 ... 2 3 4
    Replies:
    53
    Views:
    54,224
    maresca
    Jun 25, 2006
  30. CatBuilder

    PTO Unit - Need to Call in The Experts!

    CatBuilder, Oct 21, 2011 ... 2 3 4
    Replies:
    52
    Views:
    13,258
    CatBuilder
    Oct 24, 2011
  31. drortiz1

    Paddle Wheel Design Project

    drortiz1, Sep 20, 2012 ... 2 3 4
    Replies:
    50
    Views:
    19,376
    Frosty
    Oct 9, 2012
  32. yabert

    Thrust bearing for propeller shaft

    yabert, Jul 31, 2025 ... 2 3 4
    Replies:
    47
    Views:
    3,356
    gonzo
    Aug 10, 2025
  33. stonedpirate

    My outboard is spraying water at me

    stonedpirate, Nov 21, 2014 ... 2 3 4
    Replies:
    47
    Views:
    29,487
    WestVanHan
    Nov 24, 2014
  34. rich99uk

    Help With Inboard Shaft Angle

    rich99uk, Dec 3, 2009 ... 2 3 4
    Replies:
    47
    Views:
    16,822
    CDK
    Dec 14, 2009
  35. Kaptin-Jer

    Electric motors - Do they need to be so expensive

    Kaptin-Jer, Mar 28, 2008 ... 2 3 4
    Replies:
    46
    Views:
    19,168
    mydauphin
    Mar 10, 2009
  36. duluthboats

    Concept electric drive

    duluthboats, Jun 6, 2005 ... 2 3 4
    Replies:
    46
    Views:
    17,717
    artemis
    Jul 8, 2005
  37. tugboat

    hydraulic propulsion for tugboats??

    tugboat, Nov 19, 2010 ... 2 3 4
    Replies:
    45
    Views:
    14,067
    tugboat
    Nov 29, 2010
  38. SeaBirdShip

    Hybrid Ship Pulse Detonation Turbine to DC Electrics

    SeaBirdShip, Oct 15, 2006 ... 2 3
    Replies:
    44
    Views:
    21,185
    SeaBirdShip
    May 12, 2011
  39. glines

    Electric Jet Ski Conversion

    glines, Apr 26, 2005 ... 2 3
    Replies:
    44
    Views:
    87,545
    sparky_wap
    Jul 17, 2010
  40. spiel_mit_feuer

    Alternative Propulsion And Hulls

    spiel_mit_feuer, Sep 19, 2008 ... 2 3
    Replies:
    44
    Views:
    11,553
    kistinie
    Mar 8, 2009
Showing threads 1 to 40 of 991

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