Weight increase on a Personal Watercraft

Discussion in 'Stability' started by BluSky, Aug 6, 2013.

  1. BluSky
    Joined: Aug 2013
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    Location: France

    BluSky Junior Member

    Hi, I am a student, but not in engineering. Currently I am working during the summer, and I would like to organise a performance. I hope you could get me some opinions on. With a Personal Watercraft, of dimensions 3,40x1,25x1,20 metres, I would like to add decoration and different things, as part of a performance. I have the important challenge to resolve, is the relation between the weight, the flotation and the hull shape (this last one, I think I can not modify it).

    Due to I want to carry heavy things, it is forecast that total weight would be 700kg aprox, including the engine (150 hp) and propulsion system.

    The first question is about flotation. As first approach, do you think that a Personal Watercraft, where you could increase the weight up to 700 kg, could be floated without problems? Do you think I should try to concentrate the great amount of weight in the center, or along the PWC?

    Any other recomendation, comment or advice is very appreciated.

    Thank you very much.
    1 person likes this.
  2. Mike Graham
    Joined: Feb 2013
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    Mike Graham Junior Member

    Most PWC are made to accommodate maybe two riders and a tiny bit of cargo--maybe expecting a 200kg load (the manufacturer should have said what they want). Unless yours is something very special, I'd tend to think this makes 700kg a non-starter before looking at anything else. If a particular PWC can handle such a load, it would have to be determined by very specific analysis, not generalizing across PWC in general.
  3. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    click my handle for my gallery of sketch of one of a few PWC/motorcycle ideas I and some others were batting around on another thread(I may dig up latter).

    I'm confident in a very heavy motorcycle being OK on land(Honda Goldwing for god's sake).

    Not sure about PWC on water, but I sure feel even slight weight on kayak deck.
  4. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    It would be useful to know the model of your boat, and what items you would like to embark. More than flotation, I would be worried about structural strength and stability of your boat, but that's something one cannot assess without knowing more details about your project.
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The load limit will be in the range of 180kg or so. 700kg will put in the bottom; there is not enough reserve flotation.
  6. El_Guero

    El_Guero Previous Member

    You need to give more detail about what you are trying to do?

    It sounds like you need a 'bigger boat.' But, it is hard to tell with limited details.

    Do you want to carry 7 or 8 people? 700kg is a lot of weight.

    Is this just a prop? Or, will you be in the water?
  7. BluSky
    Joined: Aug 2013
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    Location: France

    BluSky Junior Member

    Hi, thanks for all your comments. I talked with a workshop of PWC and they recommend me do not increase this amount of weight. So I refused to develop idea (to add decorative stuffs at the poop mainly). In any case, I have other challenges.

  8. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    I agree with Gonzo. A PWC would not support this amount of weight. As for flotation, PWCs usually have what is called Basic Flotation, that is the boat floats when it is full of water, which rarely occurs because there is no cockpit to fill and most PWCs are designed to be watertight so no water gets inside and the engine will not get wet and will still run. They are also usually designed to turn upright if the rider is thrown off. They also have a switch that stops the engine. We call that a kill switch. Most PWCs are designed for two persons, but there are a few designed for three.
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