Increase Trim-in on Bravo 3 Sterndrive

Discussion in 'Sterndrives' started by Mat-C, Jul 28, 2009.

  1. Mat-C
    Joined: May 2007
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    Mat-C Senior Member

    Is there any way - apart from stern wedges - to increase the amount of trim-in on a Bravo 3 sterndrive?
     
  2. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    Unfortunately, I think wedges are the only way. Once the trim rams hit their inner stops, the drive simply cannot tilt any lower. No amount of modification to the stops or rams will accomplish anything other than damaging the trim system.

    If it's more bow lift you need, trim tabs or (shudder) a drive-mounted hydrofoil might be worth considering. If you really do need to tuck the drive down more, I don't know of any workable way to do this other than wedge shims between the transom and the drive's through-transom assembly.
     
  3. yipster
    Joined: Oct 2002
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    yipster designer

    you can trim the in and out range of the legs with small circular adjusters on the stern, limits beeing limits offcourse. trimtabs is another option.
     
  4. Mat-C
    Joined: May 2007
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    Mat-C Senior Member

    Thanks Marshmat, Yipster.
    No I definitely don't need to trim out any further. In fact the drive starts to ventilate if I trim out very far at all. I think the leg / engine is mounted an inch or two higher than Mercruiser recommends, which doesn't help.
    The trim angle of the boat is ok with the leg almost all the way in, but I'd like to be able to lower the bow a bit on occaision.
    Yipster - are these adjusters that you're talking about already on the drive? Or are you talking about a variation on the wedge idea? And are they something that's available off-the shelf?
    I have a diagram that seems to show that there's two possible positions for where the aft end of the trim rams attach to the leg (just above the cav plate) Do you know anything about that? One position seems to be for bravo 2 legs, the other for bravo 3. It seems to suggest that apart from the lower unit the parts are the same... I don't know.
    But if I could mount it in the Bravo 2 position (further aft) it would tuck the leg in a bit....
     
  5. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

    Mat-C
    Is this the info you refer to?
    I'm not a mercruiser mechanic, so can't advise on whether this will adjust the drive as you want - though it certainly sounds like it from reading it. But take careful note of the warning on the left hand page. Excessive bow down attitude can result in some pretty dangerous dynamic instability. How much trim does the boat have when the drive is right in?
     

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  6. Willallison
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    Willallison Senior Member

    Oh - and what's your transom angle?
     
  7. Mat-C
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    Mat-C Senior Member

    Transom angle is about 12 degrees.
    The boat never drops below 3 degrees trim and maxes out at about 4-5.

    Do you know how to check to see if the trim limit switch is set properly - and can this be done in the water?
     

  8. yipster
    Joined: Oct 2002
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    Location: netherlands

    yipster designer

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