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I don't have the means to weigh the load on each tandem axle. 

Would have expected this to be an important spec that the manufacturer, who would certainly know it, would publish. Many of these boats are stored on this type of lift. While the lifts will handle some weight unbalance, since I am installing this new, and am caring for a 4800 pound vessel, I don't want to estimate.

Is the Malibu manufacturer my only source of this info?

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@dmckelvey:  Are you looking for longitudinal CG or lateral CG, not sure by your question.  Lateral is pretty easy if you have it in the water, simply look to see the amount of list and you can calculate by the angle offset over the beam where the actual CG is.  It should be darn close to centered simply for good handling characteristics and it is hard to offset it much.  If you load one end of the boat and release it should pivot pretty close to CG, on it laterally, a bit off longitudinally due to wetted surface profile.

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For what it is worth, I had the tires removed off my rear axle in the garage. Had to move the trailer before I had the axle back together so I lowered it down on the front axle only.  There might have been 20 lbs on the tongue,  it was almost perfectly balanced.  I think that would be a good place to start and probably "close enough." Granted I have a completely different boat and trailer setup but the physics of trailering says yours should be pretty close to the same.

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@Woodski - are you referring to lateral CG or buoyancy CG?  Big diff.  regardless, the OP is likely getting too anal about this.  :)  The bunks will transfer the weight for the most part.

Edited by Eagleboy99
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@Eagleboy99:  lateral CG and a very rough way to estimate longitudinal CG although the trailer method is much more accurate.  One could also jack up the trailer and find the pivot using jack stands which will get you reasonable close.  Another method for longitudinal, do a free body diagram, you can get the big mass numbers off the engine marinizers website and do a reasonable estimate on where the CG of the hull is (very close to center) and go from there.  Probably a lot easier, either call Malibu or check with dealer on what Malibu suggests as support, they provide info since the dealers also have to be able to support boats at shows, storage, etc.

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Lateral CG is likely insignificant (unless the OP leaves tanks full or lead in the boat).  Longitudinal CG is easily calculated  with axle weights.  Or like you say, call Malibu or like I said, a trailer mfg.  But the lift  maker should also be able to tell you this.

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If I were building a lift for a vee drive, I'd set the rear lift point less than a foot aft of the back of the engine, and the front lift point an equal distance forward of the midpoint of the hull. 

But before I did that, I'd verify fuel tank location and volume first.  If it holds 60 gallons, and all aft of the engine, I'd probably move back a little more. 

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FWIW. My lift has the rear anchor about 12" forward of the transom and the front anchor is about where the throttle lever is.  Have had my 01 VLX and my 16 22VLX on this lift for a long time with no issues.  Seems well balanced.

Edited by Slurpee
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