Boat weight center

[jmondl]

I would like to ensure my 2010 Outback sits centered (bow to stern) on my boat lift, and am trying to find the weight center (called the "moment" if my memory serves me) of the boat. Does anyone know where this information is located, or how to determine that?

[rmckenney]

That would be hard to determine since you have dynamic variables at play. The amount of fuel in your gas tank changes as well as location of equipment which in turn constantly changes the location of "G" which is the center of gravity. Consider "G" as the point at which all downward forces (i.e. the weight of the boat) are focused. Therefore, to know exactly where it is at all times requires a calculation of all points of weight about a known point of reference for a completely empty boat (which I'm sure the manufacturer possesses, somewhere). In most simple terms the calculation would be weight x distance = moment / total displacement. But then this calculation is for a boat floating in water. Now, if your lift is floating in water, you will have to find the center of gravity of that and it's weight and add that to the calculation of the boat and weight of equipment and fuel. And that is all without calculating and knowing the free surface correction for your fuel tank and your bilge if you have any liquid in that and the estimated specific gravity of the fuel.

In a nut shell, not an easy answer and it may not even serve your purposes practically. The way I understand boat lifts is the best solution is to mimmic as closely the support of the manufacturers supplied trailer. Sorry for the long explanation. I'm a professional mariner and I love these inquiries!

[deerfield]

jnomdi - I keep my 2007 Outback on a Shorestation lift. The lift was installed and adjusted for my Outback by the Skiers Choice dealer local to my area. You want me to post a side view picture showing the position of the boat on the bunks? - Deerfield

[kaneboats]

Or look at the trailer designed for the boat and notice where the wheels are in relation to the engine. That should be a great hint.

[kaneboats]

Take a look at these two pictures for example:

[cab13367]

Or look at the trailer designed for the boat and notice where the wheels are in relation to the engine. That should be a great hint.

The center of gravity will be somewhere forward of the axle on a single axle trailer since there should be about 100 - 150 lbs of tongue weight the way they are set up from the factory.

[maxpower220]

CG- Center of Gravity
Moment Arm- figured by the amount of weight and it's distance from the CG.

Of course these are from aircraft terms, used to determine that the weight and where it is located will allow the aircraft to fly properly.

[jmondl]

Figuring the CG is just forward of the axle makes sense. Thanks for everyone's help. New boat should arrive next week.

[kaneboats]

The center of gravity will be somewhere forward of the axle on a single axle trailer since there should be about 100 - 150 lbs of tongue weight the way they are set up from the factory.

Always one stickler in the bunch.

[gus 08 mobius lsv]

The center of gravity will be somewhere forward of the axle on a single axle trailer since there should be about 100 - 150 lbs of tongue weight the way they are set up from the factory.

mine has a hell of a lot more tongue weight then that!
just for the heck of it i tried to lift it by myself and nothing and my dad and i barely got it off the ground