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  1. #1
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    Effect from engine too low?

    Gidday guys

    I have always thought my engine was low but had run out of adjustment. So, I got a set of CMC 5" extensions and redrilled them to give myself a 4" extension. I have now come up 2 & 1/4" and I think I can still easily come up at least one more hole. If the engine is too low can the water pressure on the underside of the A/V plate actually lift the back of the boat and give the appearance of the plate skimming the surface?
    Despite coming up 2 & 1/4" already my A/V plate is still not clear of the surface so my engine must have been way low. Like I said, I am wondering if my plate has been holding the back of my boat up all this time.

    Look forward to some opinions.

    Thanks guys.

  2. #2
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    As for lifting sort of.

    The main issue is drag. To low can rob 5-10 mph and have you up to three inches of pitch low.

    In in some situations though keeping the prop in the water overrides that.

  3. #3
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    Quote Originally Posted by Motv18 View Post
    As for lifting sort of.

    The main issue is drag. To low can rob 5-10 mph and have you up to three inches of pitch low.

    In in some situations though keeping the prop in the water overrides that.

    Thanks mate.

    Kind of struggling to work out what's going on. As I said, I have now come up over 2" but the position of the A/V plate relative to the surface does not appear to have changed, hence my theorising that it has been holding the back of the boat up. If that is the case, I am hoping that once the boat finds its running attitude then I can get the height correct

  4. #4
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    Also, the further back you go with setback, the higher you can run the motor.

    I have a jackplate on my SS2000. Height greatly affects speed. Also too low makes the boat lean left. On the other end, when I tried moving the engine up and down on my 16' Baja the effect was minimal. Through a 3" range it was not measurable on my hand held GPS. Beyond that range yes, but the sweet spot was broad.

  5. #5
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    By using the vertical extension, I have only come back 22mm, just under an inch. Despite coming up 2", the position of my AV plate relative to the water surface does not (yet) appear to have changed, so buggered if I know what is going on.

  6. #6
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    The av plate will only clear if it’s above the keel or pad.

    After that hat you have some play room till the side pickups start to get into froth or clear.
    '06 Tracker All-Fish/Tournament V-18 90 Optimax, 46.8 gps Goal one complete reach 45 mph.

  7. #7
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    Haven't tested it since coming up another hole, and heading back offshore for 2 weeks tomorrow. I'll test it as soon as I get back and let you know how I go.

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