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  1. #1
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    Default adding a 3rd pontoon log to 2 log boat

    I have a 24' pontoon boat with 19" logs on it now. I found a 18' log with a diameter of 23" that I want to add to down the middle. I know about leaving enough space between back end of new toon and the transom so the motor won't cavitate. And I know about keeping it even or ahead of the existing toons, but what about the diameter difference? Will the larger log cause the boat to teter back and forth, side to side? Or will the shorter length be less boyant than the longer toons, thus not causing this problem? Thanks so much for your help with this, Dave

  2. #2
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    Default Re: adding a 3rd pontoon log to 2 log boat

    I'm gonna guess it would be a problem. It might not teeter, but I think the middle log would always be so deep in the water that it would slow you down a lot. If the middle log floated the middle more than the outer logs float the sides, it would create some bad stress too. I don't know much about it, but those are the problems that come to mind for me.

  3. #3
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Thanks for the reply hayhauler. I actually thought it might help being deeper in the water from the standpoint of a typical runabout Deep Vee haul design? I figured that it may help getting the old girl up on top of the water with enough H.P. ? I may try and get hold of a manufacturer of pontoon boats to se what their engineers say. Thanks again for the input. Definately something to consider.

  4. #4
    Admiral Dunaruna's Avatar
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    Default Re: adding a 3rd pontoon log to 2 log boat

    In regard to the different diameters - you could always lower the outside toons so that all three are bottom level.Aldo
    Watch this space......................

  5. #5
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    Default Re: adding a 3rd pontoon log to 2 log boat

    That might work also. I will have to look into that as another option. thanks so much, Dave

  6. #6
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Aldo, it’s not about having the pontoons at the same depth; it’s about the volume of water each will displace. Obviously a larger diameter pontoon will displace more water than a smaller diameter pontoon at the same depth. Instead of lowing the smaller pontoons, you would raise the larger one up and out some...I think.I say don’t put the 3rd ‘toon on the boat. Instead, cut a couple holes in the top (one for you and one for the Mrs.), grab a couple kayak paddles and head on out. Oh, and if it’s an aluminum ‘toon you may need some sunglasses.

  7. #7
    Admiral Dunaruna's Avatar
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Originally posted by 18rabbit: Aldo, it’s not about having the pontoons at the same depth; it’s about the volume of water each will displace. Obviously a larger diameter pontoon will displace more water than a smaller diameter pontoon at the same depth. Instead of lowing the smaller pontoons, you would raise the larger one up and out some...I think.
    Agreed but most pontoon boat have the toons already hard up to (or close) to the frame - I doubt if its possible to mount the centre toon higher than the outside toons - therfore lower the outside toons brings us to the same destination - sort of. I still believe that the centre toon will cause to much turbulence and it will affect the motor.Aldo
    Watch this space......................

  8. #8
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Did exactly what you are thinking about to my boat. Worked out great, my center log is about 12" ahead of the outside logs not that it will make any differance. I have seen them ahead, even and behind(tracker). Just make sure you can get it on and off your trailer...

  9. #9
    Lieutenant Commander AMD Rules's Avatar
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Purely out of curiosity....why would a 3rd log be favorable to add?
    '86 SeaRay Seville 195BR c/w Mercruiser 170
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  10. #10
    Admiral Dunaruna's Avatar
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Originally posted by AMD Rules: Purely out of curiosity....why would a 3rd log be favorable to add?
    Increase bouyancy (decrease displacement) - lift the boat further out of the water. Cheaper than replacing existing toons with larger ones.Aldo
    Watch this space......................

  11. #11
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    Default Re: adding a 3rd pontoon log to 2 log boat

    The older pontoons with smaller diamiter logs tend to nose dive when you back out of the throttle, gets worse when everyone is up front. Third log helps keep the bow up.

  12. #12
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    Default Re: adding a 3rd pontoon log to 2 log boat

    Hey River Rat, can you pass along your phone number so I can call you. directly. I would like to talk more in depth with you about this. Thanks so much, Dave For all others interested in doing something similar, I talked with Harris Boats today. ( my boat is a Harris Float Boat )The fellow there thought it would work out great, even with the size difference. Think I'll bolt it up and see what happens. At least I know it won't sink. Thanks for all of your help, Dave

  13. #13
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    Default Re: adding a 3rd pontoon log to 2 log boat

    djwalters, e-mail me at cjohnsoniii@austin.rr.com

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