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  1. #16
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    Looks like your engine is all the way down on the jackplate, so can raise it that way. But your powerhead is way too high with that long midsection. Center of gravity very high, gonna be hard to drive safely.

    Gearcase isn't set-up for going fast, need a nosecone kit and low water pick-up. But that's a lot of work and money and unless that gearcase is a lot better inside than it is outside I would replace the gearcase with a fresher one before doing the nosecone kit/low water pick-up.

  2. Thanks DEN thanked for this post
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  3. #17
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    Thank you Captain for that....that information might of just have saved me from injury/accident. This is why I post here.
    So to the nity gity here. Using the previous pic's as reference, I can change out the mid, not sure about the lower, as I am not an outboard expert.
    Even if I did get the OB shorter by changing out the mid and lower, I can not physical move the OB down on my transom.
    I think I really screwed up building the back end here. Getting the Power head lowered is the goal, just guessing 5-7 inch???
    I haven't had this OB in the water yet so I don't know how it will preform.
    Are there different types of lower I get get a hold of?

    Suggestion and answers are much appreciated !!
    If you think this is fun, wait til next weekend!

  4. #18
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    The lower you have can get wet and you can drive it like that. Just not more than about 70-75mph without modifications.

    Those gearcase mods are time consuming and cost a bit of money (not too much) so you wouldn't want to do them to a gearcase with worn-out internals. That's all I'm saying.
    Last edited by Captaincj; 07-09-2019 at 06:00 PM.

  5. #19
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    You don't need to buy a special gearcase, you just need a good condition Merc gearcase that fits your motor/midsection (current or new mid) and you need to modify it with a Bob's Bigfoot nosecone (or similar), plumb your low water pick-up from the Bob's nosecone, and add an epoxy torque tab.

    As for your motor, hopefully the guys that know more than me (most of them know more than me) will chime in to help, but that 25" midsection is causing your problems. The 3.0L is a heavy powerhead, and it's perched way up high on that 25" mid. Will cause balance and stability problems. Once you get your gearcase modified, you would want to get the propshaft higher, which will push your powerhead higher.

    Also, the 25" midsection might have a lower RPM limit on the powerhead due to the long driveshaft.

    Just looking at the pictures, you can possibly get it wet the way it sits right now, but be very careful. Calm water, no sharp turns, don't go very fast! Most of your water cooling intakes should get water at the depth you have your lower set at now. Can't go higher with the propshaft right now anyway because you don't have a low water pick-up.

    Hopefully others will chime in and maybe someone will say not to drive it, but I think if you are careful and understand that you have a heavy powerhead sitting up high and don't make sharp turns, you could probably get it wet and start to learn to drive that thing.

    How long is your boat? What do you estimate the hull weighs?

  6. #20
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    Thanks for clearing up the gearcase , was kinda confuse, but I do understand now what your telling me now.
    I was in the garage checking thing out earlier....AND....previous owner(s) of this OB have installed a low water pick on it already,
    there is 2 holes in the front of it.. On the front side of the gearcase (prop shaft).
    It old, and the epoxy is peeling off, I thought it was just paint earlier. Does need re-done.
    I have looked into changing a midsection and not an easy job for a rookie like me. 2 choices, 20" or 15".
    If I can replace it, then I can look into way to lower the power head later, over the off season.
    Where would I find a mid? I have seen seem on ebay and around, but don't know what would fit or not.

    forgot to answer.
    length is 16 1/2'
    hull only weight. 750 -900lbs (cedar wood, glassed, marine epoxy)
    Last edited by DEN; 07-09-2019 at 09:48 PM.
    If you think this is fun, wait til next weekend!

  7. #21
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    Looking at your pictures, I still don't think you have a low water pick-up. Make sure you have a water pressure gauge just in case I'm right...

    Don't want to cook the powerhead.

  8. #22
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    Dam. that motor is way too low

  9. #23
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    Quote Originally Posted by Northlakeguy View Post
    Dam. that motor is way too low
    By motor, do you mean propshaft? Remember he has a 3.0L on a 16' hull and a 25" midsection! And probably no low-water-pickup.

    Just saying.

  10. #24
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    That is a standard 3.0 gear case and the upper pickups have not been plugged (you can see through them in the pictures). Is that five inch spacer able to be removed? From the looks of things, it can come out and will be much closer to where it will run. The skeg looks small as well (again not a high speed recommended case). Try to pull the spacer out between the exhaust can and the case, put it in the water and take things slow. Watch your water pressure and temp-you will end up filling the side pick ups so that you don't aerate your intake water and give it an escape route before the pump can pull it through.

    Joe

  11. #25
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    Joe, so you think it's actually a 20" mid with a 5" spacer and longer driveshaft?

    That would be great for DEN if true.

  12. #26
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    Speaking as some one who started with a 25" mid jacked way up and switching to a 20" I will say it is a huge difference in centre of gravity, like night and day. mind you it was on a Vee hull but if its noticeable to me in a Vee it will sure cause you some CG wobble on a cat. we are all limited by budget but definitely be cautious when you get up there in MPH running the 25" mid.

  13. #27
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    That lower unit looks like the cooling water pick up is in the stock location. If you just want to get on the water and play, that motor can be run on that hull no problem without a nose cone or low water pick up. Downside to this set up is that you are leaving a lot of performance on the table, but it will run. Just make sure you don't go so high with the motor that it gets starved for cooling water. Start with the cavitation plate the top of the tunnel and you will be fine. This ought to put the prop shaft even with the bottom of the sponsons and ought to be a good starting point for the stock lower unit and stock prop. I suspect speeds will probably be about 45-50 mph with a stock pitch prop (17-19 inch pitch) and the RPMS will be off the chart. However, in order to get maximum performance from the motor, you will need to raise it on the transom and obtain a surfacing style prop (not aluminum) with the diameter and pitch that puts the motor in its maximum hp operating range (about 5500-6000 rpms stock). It will help to have a shorter midsection too.
    Last edited by bajarick; 12-12-2019 at 02:34 PM.

  14. #28
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    A few thoughts. The boat is heavy for a 16 ft tunnel. Porpoising issues (maybe big ones) are to be expected. Surfacing the prop will not help but leaving it buried will give some control over that. Running at the limit of the stock water pickup might be the best thing for this boat.
    A 27 inch mirage prop will run it to 80 before blow out with the 1.75 gear that's in that fleet master lower if it's not over trimmed to get there. Plenty fast enough to flip a short tunnel in a chop with a head wind.
    That mid can't be converted to a 20, it has no spacer.
    The transom is not built to tall.
    The boat will float just fine.
    I don't think 150 hp would push the boat past 60.
    Great boat to learn on and survive while doing it.
    Most important thing, use the boat.

  15. #29
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    as rigged above the boat will porpoise. it looks like the motor is 4" too low or more. that about 600 lbs and the transom will be too low in the water. getting on plan could be an issue.

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