too much weight for my solar powered pontoon styled boat

Discussion in 'Stability' started by Captain Sunset, Mar 5, 2019.

  1. Captain Sunset
    Joined: Jun 2012
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    Captain Sunset Junior Member

    hi,

    i am looking to add a third pontoon in the middle of my pontoon boat, making it a tritoon. Is it important if the center hull is the same as the other ones? can it be bigger or smaller in diameter?
    the most imortant for me is to not decrease the stability The boat should remain as level as possible at all times since she is used for living on.

    My brother, (who is not a boat builder,) told me to take a smaller diameter center tube, that way it would only create drag when the boat is loaded hard and otherwise be mostly out of the water....

    A larger center tube would add extreme extra flotation, but i worry that it will mak it less stable, having the boat wanting to lean on either the star or port side tube? Or does it not work that way on the water?

    Or is the safest way to simply add an identical third hull? (i wanted to try out a different hull so i could in a later stage perhaps add bow and or stern thrusters)

    Speed is not my aim, but having very little power since i only use solar, i am still concerned with hydrodynamics.

    About calculating the flotation and so on, i feel confident.

    The solar powered vessel worked well, thanks for all the info i got here about 5 years ago (also see my profile for more info on the vessel). Now i want to add a cabin to live in (as opposed to the tent i lived in, in the past). The added weight makes it necessary to add a third hull to the pontoon construction.

    I can add pictures if i log in again from my smart phone should it be necessary,

    thanks for your input!
     
  2. BlueBell
    Joined: May 2017
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    BlueBell Ahhhhh...

    We need a picture bigger than 3cm please.
     
    Last edited: Mar 5, 2019
  3. Captain Sunset
    Joined: Jun 2012
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    Location: Belgium

    Captain Sunset Junior Member

  4. Captain Sunset
    Joined: Jun 2012
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    Captain Sunset Junior Member

    my main question is: would the stability of a pontoon house boat be negatively affected by a different diameter center pontoon? So this does not concern go fast boats, sailing, seagoing vessels and so on... just, would the boat have more a tendency to lean when people move around if the center hull is different diameter? or does that not matter very much? I am unsure how else to phrase it
     
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Yes, the stability will be affected by the center pontoon plus the added weight on top. How much depends on the dimensions and weights.
     
  6. Captain Sunset
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    Captain Sunset Junior Member

    in which case will the boat lean more:
    the center pontoon is the same diameter as the side pontoons,
    or the center pontoon is a bigger diameter as the side pontoons
    ?
     
  7. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Pay attention to Bluebell and upload a drawing of his pontoon with enough data so that, if someone wants, he can do some calculations. Also indicate what changes are possible and what are not. For example, could the shape of current pontoons be changed?
    What "stability" are we referring to? At this time no one is able to know (unless you have a fortune teller's crystal ball) if the stability increases or decreases. Both cases may be inadequate for the comfort of the house
    If what concerns you is only stability, you can check with numbers, the most appropriate configuration. In the case of your pontoon, as always, it would be convenient to have a well detailed SOR.
     
  8. Captain Sunset
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    Captain Sunset Junior Member

    what is a SOR?
     
  9. Captain Sunset
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    Captain Sunset Junior Member

    i actually don 't need calculations, i am looking for a straight forward answer:

    does a center pontoon hull that is larger diameter than the side pontoons add / or decrease / or does not influence / the roll of a pontoon vessel, all other parameters staying the same?
     
  10. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Statement Of Requirements : define how you want it to be and behave your pontoon.
    Stability will undoubtedly change. But that change may be very small or not and it may be better or it may be worse for what you need.
    If you do not need calculations, how do you want to get a valid answer?
     
  11. Captain Sunset
    Joined: Jun 2012
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    Captain Sunset Junior Member

    Statement Of Requierements:

    I want the boat to stay as stable as it is now, or even more stable. This concerns mainly people moving around the deck.

    HOw an answer can be given where no calculations are needed: example:
    what has more flotation? a bigger or a smaller balloon? answer is possible without doing any calculations.

    So, i am trying to find someone who can tell me if a bigger center pontoon, meaning that it will protrude deeper in the water than the side pontoons, will make the boat roll more easily or not than a center pontoon that is the same size as the side pontoons. I am also interested if a smaller center pontoon would in diameter would cause more rolling than a same size center pontoon. but this last question is more of acadamic importance since i will add either the same size pontoon in the center or a bigger size pontoon in the middle. I do not know this myself. I would hope someone has real life experience with this situation.

    I would really love to hear from someone who knows this.
     
  12. TANSL
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    TANSL Senior Member

    Who could answer if the modification will improve or worsen "something" if we do not know what is "something" and what value does it have now?
    There are different ways to calibrate stability. Whichis the one that worries you the most?. Another option is to make a balance period that makes the transverse movement of the boat more comfortable. The initial stability can be increased a lot, for example, but that will make the boat less comfortable. But what is clear, for me, is that adding a new buoyance body will totally alter the pontoon's draft, its center of gravity, and the configuration of the waterplane area. Since, I suppose, this is an important issue for you, I do not know why you are insisting that "someone who knows the subject" will answer you without knowing your boat.
    Good luck.
     
  13. Captain Sunset
    Joined: Jun 2012
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    Captain Sunset Junior Member

    This was a test where I added weight to see how she would handle.
    I am going to add more weight now so I will need a center hull for added buyancy. As you can see, it is not about going fast, it is about comfort.
    I know she is better when deeper in the water.
    What I don't know is if the Center Hull protrudes deeper if that affects roll negatively.
    I will do scale tests tomorrow in the swimming pool.
    One with Center Hull same dimensions.
    One with Center Hull same dimensions bit positioned deeper in the water.
    One with a larger diameter Center Hull to see what happens to the roll.
     

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  14. Captain Sunset
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    Captain Sunset Junior Member

    Which one will have less roll all other variables a constant?

    sorry it got posted sideways, the red situation is the one with the bigger central hull
     

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  15. Captain Sunset
    Joined: Jun 2012
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    Captain Sunset Junior Member

    Hoping this clears things up. Now if someone thinks they need numbers to figure this one out, ask me for what numbers you want exactly and i can give them. but i think this is a question of common sense and principles. Not a question of applying math to get a number as an answer.
     

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