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Need engineering assistance on a new concept product

  1. Feb 18, 2007 #1
    Hey guys,

    I’m currently working with a personal water craft docking company that is trying to redesign there current port series models into something that can capture the market as well as be designed to hold future personal water crafts i.e. jet skis and there future bulkier sizes and weight differences. The old design consisted of simply ramming the Jet Ski or PWC (personal water craft) onto the port while our design you simply drive the Jet Ski between the two pontoons thus cradling the pwc and creating a frictionless system. This new design will be able to lift the pwc from the center of the port and raise it above sea level in order to create the same affect as if it were on there current port (raised out of the water). The concern here is how to design the lever system and mechanics in order to make this all work. Searching around I was able to find good examples of products with great potential to be the lift; such as race car hydraulic lifts with twist turn lowering handles and a simple two pump system to raise the car. Each pump raises it about 5” which is pretty cool when in comparison to a bottle jack or something of that nature. Current ports come with bulk heads or stoppers and since our product simply cradles the pwc when entering we hope to make this new port a universal entry. The bulk head has to be able to lower or rise at both ends to allow for the pwc to enter. I think this is where the lever for the hydraulic lift could be located and hit and triggered or compressed by the PWC’s weight? Any insight on designing, engineering, anything would be greatly appreciated in my quest to create a better design. Posted on that web address is a rough of the design to help you guys inorder to help me.

  2. jcsd
  3. Feb 19, 2007 #2


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    You won't be able to use the PWC's weight to lift itself out of the water any more than you could lift yourself into the air by your own shoelaces. Sounds like you could make quite a nice hydraulic lift though (either hand or electric powered).
  4. Feb 20, 2007 #3
    Why not build an angled ramp with rollers and pneumatic loaded side cushioned rails,(like pneumatic shock absorbers), to guide the craft and hold it to center as the craft is driven up onto the unit. The unit rocks over once the center of gravity is surpassed on the upper end and locks it self into place. The rollers, (each with tooth gears, one on each side of each rubber non-skid roller), are only allowed to turn clockwise while in the receiving mode one way in and rachet locked with a pall, (this mode is automatically set when the craft is launched out). It kinda looks Like a boat trailer with rollers without an axle or a tongue. When the craft is to be relaunched the locking pin is released, the operator leans back, (on a PWC), or steps back to the rear, ( for a boat), to transfer the weight pass the center of gravity and the rollers now free to turn the other way releases the craft down the ramp back into the water as it rocks downward utilizing gravity and the crafts own weight. I have a drawing depicting this application. I use to live on the water front and I wanted to have a permanent out of water storage for my Boat that didn't need a power source to operate. I designed a system that provides for Quick and Safe loading and immediate unloading. It can be fixed to a structure or free floating but it must be anchored securely to allow for the thrust of the crafts propulsion to allow the hull to climb up onto the rollers and advance. I can provide details if interested. I researched all of the hardware needed. It's actually quite simple.. not much exotic hardware involved. The gears have to be machined and attached to extended shafts on the rollers. Should be easy to accomplish. by the way there are also duel air shocks to cushion the the crafts tilt over into the locking position, and cushios as it tilts back for launch. Like an air bag the piston spills out the air providing cushion as weight is applied. When the craft is launched the cylinders fill with air again..ready for the next retrieval. The only question you should have is how to advance the craft upwards an inch or so to release the pall..I have a simple solution to that also, it's really not a solution it happens during the locking phase automatically. the craft sits slightly lower at the front on the plane allowing for the easy disingagement of the pall. My drawings are propriatary. Later, Koonism
    Last edited: Feb 20, 2007
  5. Feb 21, 2007 #4
    what brewnog says is true. instead of lifting PWC out of water, you can form a film of forced water getting ejected rearwards from the holes (orientaion towards rear). the holes are in immersed portion of the body. this would help you in overcoming friction.
  6. Feb 21, 2007 #5


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    Have you seen the designs for 4 post lifts in car garages? I would think that would be a good starting point. They are mostly electric motor driven with 4 screw jacks, one in each post. Since it was in the water, you could look into a hand pump/hydraulic set up or an electrically driven pump.

  7. Feb 21, 2007 #6
    Yes you can use the forward momentum of the PWC to go up onto the rollers and transfer the weight past center of gravity, on a cradle that will rock forward and lift the back end out after it rocks over and locks into place. Like I stated in the previous post, You don't need an electric motor, a hydraulic pump, you don't need any energy source. The forward motion of the craft is the energy source. You will need a few rollers, a few cheap pneumatic pistons like the ones used on a storm doors or screened doors to keep the door from slamming. A locking mechanism..with a release lever, May not need the Rachet Rollers.... Reg. boat trailer rollers will probably work fine after the center of gravity is adjusted for a slight weight advantage to the front upon climbing onto the cradle This is to create a slow tilt to forward . The whole cradle must be angled with entrance roller's top right at the water level. It's not Rocket Science. Don't over Engineer it...keep it as simple as possible with galvanize for fresh water...and 316 Stainless Steel on all metal parts used for a salt water environment. it will work.
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