How to align this prop shaft

Discussion in 'Inboards' started by holdfast, Mar 17, 2014.

  1. holdfast
    Joined: Nov 2013
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    Location: Spain

    holdfast Junior Member

    Hello,

    I have to align the propeller shafts on this boat. It is a little bit more complicated than usual as each shaft has four supporting points. There are two bushins outside the hull (as you can see in the picture), the shaft gland, a ball bearing and another thrust bearing before the Aquadrive system.

    I don't really know wich of the supporting poins is in the right position yet. I'm planning to do it with a laser, any advice please is allways helpfull.

    Cheers.

    [​IMG]
     
  2. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    The first strut..p bracket ....will be trouble. How is it mounted in the hull ? Is it adjustable, shims, set into chockfast or epoxy

    Are there three cutlass bearings ?

    I believe the rule for distance between shaft bearings is 30 times diameter.

    Your shaft looks long and thin.
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The struts were there already, so unless the hull had some structural damage, they should be OK. The engine should be aligned in the water after the hull swelled up. Planked boats get loose when dry and change shape. The fastener pattern shows it is either double planked or seam battened which minimized the problem.
     
  4. michael pierzga
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    michael pierzga Senior Member

    Possible that wood boats change shape. Be careful that the aft jackstand its not deforming the hull.

    Have a carefull look when you pull the shaft.
     
  5. holdfast
    Joined: Nov 2013
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    holdfast Junior Member

    Thanks Michael anf Gonzo for your replies.

    I attach some pics of the seal, the ball bearing and the thrust bearing.

    We are going to change the seal and the ball bearing and of course the bushings from the struts. The whole shaft needs to be aligned from 0 as it is not perfectly centered.

    I have installed new engines and there is no way to aligned them up with the engine mounts adjusting margin. Now the engine mounts are all the way to one side and they are still not aligned.

    My concern is if the struts need to be adjusted, it is going to be very difficult as the haven't been taken apart for ages.

    Are you sure the boat changes the shape after less than one month out of the water or with the jackstands? I know is made of wood but it is pretty solid too! I was planing to do all the job in the shed and I think there is no other choice except leaving the enging alignment after the launching...

    I think the starting point is to put the engines in the center position of the mounts, try to align the shaft betweeen there and the aft strut, wich I will have to check if it's in the right position too (I don't know how yet..)

    I will keep you updated, any advise allways help

    Cheers.

    [​IMG]

    [​IMG]

    [​IMG][/IMG]
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    This is a pretty critical aspect of a new engine install, so if you're having difficultly with the associated problem solving necessary in these type of upgrades, you'd be best advised to hire someone that has a few dozen installs under their belt to help. Basically, you just can get it close, while on the hard and you fine tune to a few thousands of an inch, once she's taken up. Anything less than this will insure issues, once underway.
     
  7. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    Hard to see what your engine installation looks like.

    It would be much easier to move the engine into the shaft run , rather than reseat all the struts and bearing and bring the shaft to the new engine position.

    Chances are that your p bracket setup is reasonably well aligned

    Saddle bearings are easy to shim and adjust. If some misalignment is found in your P bracket Setup it may be easiest to adjust the saddle.
     

  8. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    The shaft alignment is simple and can be done without special equipment.
    Once the shaft is removed and new cutlass bearings in place you could use a laser to check the alignment, but when you push the shaft back in, you certainly feel if one of the bearings is off center.

    The engine is a different matter, because even with a laser you can only align in one plane and there may still be an axial angle.
     
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