sterndrive upgrade

Discussion in 'Boats, Motors, Trailers and Towing Rigs Forum' started by goddan, Sep 8, 2017.

  1. goddan

    goddan Member

    Hi, I'm thinking about upgrading from my mr1 stern drive to a duoprop or bravo 3. Is it a worth while upgrade and which is better?. Thanks for any input
     
  2. bullyjack

    bullyjack Active Member

    I went from the stock 350 to a 383 stroker with the alpha gen 1. Boat was slow to plane and topped out at 32mph. Removed the alpha and installed a bravo3 dualprop with 21 pitch props, with 5 people, fishing gear, food for the day and a full tank boat planes in under 5 sec, tops out at 44mph and cruises at 28-30. Lot more control backing up as well.
     
    WaterRats likes this.
  3. goddan

    goddan Member

    Thanks bully jack. I've heard from guys same speed as before400 to 600 less rpm with duoprop
     
  4. bullyjack

    bullyjack Active Member

    Mine dropped 1000rpm, i think the leg the previous owner had on was geared for a v6.
     
  5. goddan

    goddan Member

    Wow,that's some fuel savings for sure
     
  6. Oly1

    Oly1 Active Member

    And quite a bit easier on the motor for the long run. Are people who put duoprop out drives on getting more overall hours on their engines as compared to an Alpha 1 out drive?

    Oly
     
  7. ericl

    ericl Active Member

    I have been doing a lot of repower research.

    Indirectly see stuff on stern drives such as:

    Dual props don't do much below 25 mph.

    Most of Volvo Penta power package complaints are about the stern drives.

    Weight differences will be a minor issue.
     
  8. wolf

    wolf Well-Known Member

    Dont know about the above statement i can run 2500 rpm and at 18 mph still on plane with duo prop .
    one thing about duos is they get up on step WAY faster and will hold you better.
    ive been running them for a long time pretty cool systems , re-powered with the new LS series engine and duo prop VERY impressed with the system...
     
    bullyjack and kaelc like this.
  9. bullyjack

    bullyjack Active Member

    I agree, on step alot faster!
     
  10. I'm going to disagree with you. The duoprop outdrives help plane slower, improve holeshot, and improve low-speed maneuvering (especially reverse) when compared to single prop sterndrives
     
  11. robertg

    robertg Member

    have a 25 foot byliner cierra, put a bravo 3 with the duo prop on 2 years ago, faster out of the hole, planes down to 18 knots, and docking is a dream, when you select reverse the aft end of the boat takes a few seconds to react but is sucks the stern end into the dock before the reverse takes effect, could never understand why but it does
     
  12. wolf

    wolf Well-Known Member

    I tried to upload a file (The uploaded file does not have an allowed extension.)this is what it says

    to here to show the how fast my boat which weighs about 8000 lbs loaded comes up on plane at about 20 ft . if someone knows how to post it ill send you the video by email
     
    noluck likes this.
  13. ericl

    ericl Active Member

    Whatever you do not prop the boat so that you do not achieve rated WOT RPM for your motor. Otherwise your motor will be overloaded.

    As for disagreements, they are great. My info is generic, some other info is unique to 1 boat model. The performance on your boat may not match that of other boats.

    I'd agree that the dual prop SHOULD be better. The only safe bet is to get info on your specific boat or buy another boat.
     
  14. goddan

    goddan Member

    I bought a Volvo penta engine and 290 dp duoprop.
     
  15. Sir Reel

    Sir Reel Well-Known Member

    This video is old and kind of corny but shows the performance differences of duo-prop vs single prop in identical boats.

     

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