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  1. #1
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    Jackplate on a bowrider

    Hi everyone,<br><br>I purchased a 2009 larson 186 SEI and moved my motor a 2.5 175 mercury with a bob's tuner, drilled midsection, nosecone and alien cowl onto it and put the 115 evinrude it came with on my panther(vmate 2) and sold it. I've been testing my props and trying to get it setup but have struggled a bit so far i have tried:

    25P quicksilver 56MPH on the larson at 5450 68MPH at 57 to 5800 on the panther
    25P trophy plus 55MPH on the larson at 5600 to much slippage getting on plane and in turns
    22P high 5 59.5MPH on the larson at 6100

    All speeds are GPS, the motor is 1 hole up from as low as it will go i believe the quicksilver and trophy had to much slippage probably from the motor being to low? The high five lifts the boat and carries the bow very nicely i was very surprised after reading other peoples reviews it also is so smooth great on plane.

    The trophy plus porpoised and didnt lift the bow very much at all

    The quicksilver was fine getting on plane but i believe the boat may be to heavy for it or motor to low.

    I am picking up a 24P high 5 and will try that i want to get to 60 plus MPH GPS and be able to rev lower as i still have the oil injection etc hooked up. I have tried to search about jack plates on bowriders and saw nothing related but am thinking of two options:

    1 raise the motor one hole and try that

    2 Get a 6" jack plate and than adjust load dependent but with no reviews i do not know how a jackplate is on a bow rider will it cause porpoising etc. and would it be worth it? Has anyone had a jackplate on a bowrider or similar weight boat and had good performance gains in plane speed/top speed or would it just be more worthwhile to raise it and leave it on the transom? How far below the bottom of the boat should the prop be on a bowrider? If you do skiing tubing etc. should i still delete the oil injection and timing stabilizer and set to 23 degrees or just leave them as is as they are working fine and there is quite a bit of midrange rpm towing with a load eg. a skier?

    Thanks,
    Last edited by cameronj; 07-20-2020 at 07:21 PM.

  2. #2
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    Click image for larger version. 

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    As you can see in the picture i believe the motor being back further would have the boat balanced a bit more as the weight of this motor is much less than the 4 strokes on two of the same boats on my lake that have them. Also once one person sits in the front the back comes right up quite high

  3. #3
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    Quote Originally Posted by cameronj View Post
    Hi everyone,<br><br>I purchased a 2009 larson 186 SEI and moved my motor a 2.5 175 mercury with a bob's tuner, drilled midsection, nosecone and alien cowl onto it and put the 115 evinrude it came with on my panther(vmate 2) and sold it. I've been testing my props and trying to get it setup but have struggled a bit so far i have tried:<br><br>25P quicksilve&nbsp; &nbsp; &nbsp; &nbsp;56MPH on the larson at 5450&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 68MPH at 57 to 5800 on the panther<br>25P trophy plus&nbsp; &nbsp; &nbsp;55MPH on the larson at 5600 to much slippage getting on plane and in turns<br>22P high 5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 59.5MPH on the larson at 6100<br><br>All speeds are GPS, the motor is 1 hole up from as low as it will go i believe the laser 2 and trophy had to much slippage probably from the motor being to low? The high five lifts the boat and carries the bow very nicely i was very surprised after reading other peoples reviews it also is so smooth great on plane, the trophy plus porpoised and didnt lift the bow very much at all, The quicksilver was fine getting on plane but i believe the boat may be to heavy for it or motor to low.<br><br>I am picking up a 24P high 5 and will try that i want to get to 60 plus MPH GPS and be able to rev lower as i still have the oil injection etc hooked up. I have tried to search about jack plates on bowriders and saw nothing related but am thinking of two options:<br><br>1 raise the motor one hole and try that<br><br>2 Get a 6" jack plate and than adjust load dependent but with no reviews i do not know how a jackplate is on a bow rider will it cause porpoising etc. and would it be worth it?&nbsp;<br><br>Has anyone had a jackplate on a bowrider or similar weight boat and had good performance gains in plane speed/top speed or would it just be more worthwhile to raise it and leave it on the transom? How far below the bottom of the boat should the prop be? If you do skiing tubing etc. should i still delete the oil injection and timing stabilizer or just leave them as is as they are working fine?&nbsp;<br><br>Thanks
    Dude, this is wayyyyyyyy tooooooo much information packed into one paragraph with so many questions.

    From what I can pull out of that, here is the short answer: Yes you can see some improvements with using a jackplate. The amount of setback will vary depending on hull, part of the fun of figuring out optimum setup.

    Yes, you might see some proposing when pulling a skier or tube. I found the easiest way to fix this was to have spotter and passengers sit up front.

    Most will tell you to delete the oil injection as a cheap form of insurance. No idea about timing stabilizer.

    My personal experience is I set my motor at different heights depending if I want top end or hole shot for speed. Lower for hole shot, other for speed. The amount I set it at will also vary with which prop I use for each application. I have 2 for top, 2 for hole. All are best at different heights. Also worth noting, if you are going to mess with motor height, you might want to get a water psi gauge. Also cheap insurance.

  4. #4
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    Sorry was not like that when i originally posted thats weird how that happened i reedited the post. Thank you SS minnow

  5. #5
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    That nose cone is just extra drag slowing you down. I doubt you'll be able to get the motor high enough to need the low water pickup. The Merc V6 gearcase doesn't blow out until 80 mph or so. On a light pad hull like a Hydrostream or Allison the nose cone helps handling at lower speeds. On your Larson it's just extra hydrodynamic drag. You'll probably pick up a few MPH going back to a standard gearcase.

    Alien cowl and drilled mid on that boat are kinda like running open headers and a hood scoop on your mom's Vista Cruiser but if you dig the racket (and your old lady doesn't complain) more power to you. Plenty of guys running around with "captain's call" on their Crownlines running 45 mph and sounding like an open header jet boat, they'll probably want to anchor by you at the sand bar!

    The high 5 is probably a good prop for that rig and a jack plate might help, I'd probably go for 6". Make sure it looks like you have enough slack in your steering and control cables to accommodate the setback...


  6. #6
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    You can get it in the low 60's, remember, your panther weighs way less than that Larson....
    "One of the penalties for refusing to participate in politics is that you end up being governed by your inferiors". Plato .

  7. #7
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    The jackplate is a good idea prob 6in setback ? If possible fi d a tempest In ur pitch range to try , they have very good bowlift and speed , u cant get optimum performance from ur setup without a jp imo. 18.5 ft. 6in sounds perfect to start with then raise it to round 2in below (prop to pad) and try a tempest (24?) , also the PVS plugs help with slip with trophy and tempest, you will be able to turn more rpm with all props as the motor raises higher
    Last edited by Merc 2.5; 07-20-2020 at 09:38 PM.

  8. #8
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    Nosecone will be killing speed until you can exceed 80mph with little to no positive trim. Stock lower or Touquemaster case is what that boat needs. Jack plate and water pressure gauge do not let pressure drop below 10psi, may find you need to plug the top 2 water intake holes on stock lower or install Merc scoops.

    Dave
    1980 Cougar 19 tunnel,90 2.4L Bridgeport EFI in middle of restoration.
    1988 BAJA Sunsport 186, 96 225 Pro Max
    79 12' Auminum, 95 Merc 9.9
    RIP Stu
    "So many idiots, so few bullets"

  9. #9
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    Thanks for all the help, had to order steering cables to accommodate the jackplate. I did pick up a balanced 23P tempest plus as per merc 2.5's recommendation and picked up some MPH got 62.1 on GPS at 55 to 5600RPMs with the cavitation plate still well below the water line on plane, i think the 6" jackplate will be a nice addition and dial it in.

    Unfortunately my 22P high 5 i had that was modified was stolen right off my boat at the dock by someone and the 24P high 5 i picked up performs no where similar, i get 54 MPH at 6XXX RPMS and ventilates bad getting on plane and porpoises like crazy with any trim at all. This 24P is a older model with the smaller ventilation holes no caps. I wonder if i can have them sealed and have some cup added to the prop to increase lift and reduce slippage? That 22P lifted the hull better than the tempest plus the 24P high 5 is no where near either. Was there that drastic of a change in the earlier high 5s compared to the newer?

    I also will be putting my original lower unit on as i will not have the motor high enough or be fast enough to reap any benefits from the nosecone.
    Last edited by cameronj; 07-25-2020 at 08:44 PM.

  10. #10
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    Well least it over 60 now haha. when u get jackplate on and setup it will help bowlift also, with weight further off transom

    O also that original unit will prob give bowlift to
    Last edited by Merc 2.5; 07-26-2020 at 06:48 PM.

  11. #11
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    put a set of doel fins and your hole shots will improve. the pitch for speed.

  12. #12
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    Hi everyone,

    Figured i would update in the case anyone is searching for something similar as i had a hard time searching before and after gains with raising a motor. I struggled with deciding on a jackplate and bought a vegas with a hydraulic jackplate i will swap over before selling in the spring.

    I raised the motor though from the second lowest hole to the highest and had a huge performance increase especially with plane time. It literally jumps on plane now, steering has way less torque, gas mileage def. improved and now anytime i open it up with a passenger i can get 64 to 65mph up wind/down wind myself, 2 or 3 passengers at 58 to 5900 rpms(speed/rpms dont change) with a best going with the 8 inch to 1 foot waves of 67mph with a passenger at the same Rpms. It will not rev higher even if i trim up until i get some ventilation and lose speed, seems like there may be something limiting my rpms

  13. #13
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    Quote Originally Posted by cameronj View Post
    Hi everyone,

    Figured i would update in the case anyone is searching for something similar as i had a hard time searching before and after gains with raising a motor. I struggled with deciding on a jackplate and bought a vegas with a hydraulic jackplate i will swap over before selling in the spring.

    I raised the motor though from the second lowest hole to the highest and had a huge performance increase especially with plane time. It literally jumps on plane now, steering has way less torque, gas mileage def. improved and now anytime i open it up with a passenger i can get 64 to 65mph up wind/down wind myself, 2 or 3 passengers at 58 to 5900 rpms(speed/rpms dont change) with a best going with the 8 inch to 1 foot waves of 67mph with a passenger at the same Rpms. It will not rev higher even if i trim up until i get some ventilation and lose speed, seems like there may be something limiting my rpms
    I know this is an old thread but I've been considering the same thing lately. I'm curious to know from the OP how the boat handles at high 60's, does it walk a lot or still stable? And what prop did you settle on to get those high numbers in your last post?

  14. #14
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    On even number high five props they are really for small gear case motors. They are usually about 12.5 inch diameter. Uneven number props are usually 13.5 inch diameter. They would be a better bet on your boat as the larger diameter will help everything.

    Carter Powell

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