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Reading the OB trim gauge

thomasgf
thomasgf Member Posts: 8 ✭
in General Questions
i am new to boating and new to reading my trim gauge. When I bought this used 2005 GS201 OB the trim sender arm was broke so I replace that part and now the trim gauge works. Before getting this fixed I really wasn’t sure how much I was trimming up when speeding. Today under WOT after planning I trimmed up to about 3/4 up on the gauge. Well my temp sensor kicked on and boat reeved down and I quickly shut engine off. I think I was too high and the OB wasn’t sucking enough water.  My gauge reads down, 1/4down, middle, 3/4up, and up, How to you guys/gals work the trim gauge when speed boating? Also FYI my engine pees good so no issue with my OB water intake system.
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Comments

  • parachuter
    parachuter Member Posts: 7 ✭✭
    Personally I think the trim gauge is useless. I’ve always  used the rpm gauge, sound of the motor, and the bow placement to determine the motor placement. Not to mention just looking over my shoulder to see the motor placement works for me. I’m sure others would agree with me as well. 
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  • cjjjdeck
    cjjjdeck Member, Moderator Posts: 1,872 ✭✭✭✭
    I agree with parachuter, the trim gauge really helps in letting you know where the motor is at, especially in shallow water or in prep with pulling the boat up onto the trailer.  Your engine and overall boat performance dictates where the "sweet spot" is on trim.  Porpoise-ing   will be one indication that trim is not optimal, high revs and slow speed is another.  Water conditions (choppy water) can also have an effect on where the trim position works best.  Number of passengers and weight distribution also has a dramatic effect.  As I'm underway, I keep making adjustments until I find the sweet spot where everything runs smooth.
    2012 SD237 I/O Mercruiser 5.0L MPI ECT/ Bravo 3
    2012 Load Rite Elite Tandem axle trailer

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  • thomasgf
    thomasgf Member Posts: 8 ✭
    Yes ok good points. I have to get better watching my RPM and speed gauges while underway.  I have a Johnson DF140 and the rpm range is 5600-6200. So I will keep playing until I find that sweet spot. Most likely probably around the half trim area.  Lesson learned. I just never want to cause that overheat to the OB again. Scared the crap out of me.
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  • cjjjdeck
    cjjjdeck Member, Moderator Posts: 1,872 ✭✭✭✭
    Understood!  Here's a link to a pretty good article on using engine trim that you might find interesting: 
    https://www.discoverboating.com/resources/how-to-trim-a-boat
    2012 SD237 I/O Mercruiser 5.0L MPI ECT/ Bravo 3
    2012 Load Rite Elite Tandem axle trailer

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