Re: [PSUBS-MAILIST] Weighing

[Coalbunny <coalbunny@vcn.com>]

I saw some guys make a LPG tank once and they did it a bit differently. 
Once they finished the tank they were going to mount it to a trailer. 
So they lifted one end of the tank and put a piece of 3" steel pipe
under it.  Like a "teeter totter" thing.  Then they would push it
forward until the weight shifted and after about 20 minutes or so they
had it marked for the center of gravity.  They found the C0G wasn't
"dead center".  Off by a foot I think.  I forget.  Has been about 20
years or so.
Carl


Carsten Standfuss wrote:
> 
> Weighing the final new submarine before the first dive is a most
> important issue. But even very important is the longitudinal center
> of gravity. If the weight is correct.. but imagine all locate in the
> stern.. it will maybe never swim on even keel.
> 
> I meassure on my last motorboat this longitudinal center this way :
> (Works only with single axis trailer..) Drive the boat on trailer to the
> road scale - Put the trailer main axis on the scale and the forward
> single wheel on the road in front of the scale - remove the car.
> Meassure the weight. Now put the single forward wheel on the scale -
> probably on the same spot at the scale as before the main axis - and the
> main axis on the road. Meassure this weight. Drive home - mark
> the excact place were ths sub was locate on the trailer and remove
> the sub from the trailer and make the same weight meassure with the
> trailer alone.
> Now you can calculate the weight and the center of longitudinal
> weight. Give you a good indication were the reserve lead should be
> place. Do not forget to calculate the crew and other items
> not on board during the meassuring..
> 
> The maths for the calculation is very simple - but a natural english
> speaker can explain this much easier than I am..
> 
> Cssx hull was meassured during delivery the main hull 2 months before.
> Calculation was 31,25 t and meassuring was 31,00 t - good - give me
> playground - most time things get to heavy..
> 
> The center of longitudinal weight was also checked with a single mobil
> car crane ! Did this that way:
> Calculate the center - mark this on the drawings and mark this
> center also on the real hull.. than meassure the excact distance
> - say as example 9 feet from this point forward and aft this point.
> mark this on the hull and give the crane driver the instruction
> to fix the ropes on this spots. Lift the boat and if the boat
> gets from the trailer perfect horizontal.. everything is well.
> If not - put it down - move one rope and lift again.. if it is
> horizontal now - mark the position of the rope on the hull for
> recalculation. Cssx both hulls parts were perfect horizontal
> at the first lift. PS.: Make shure that both ropes have the same
> length.. (But two spring scales in the ropes give you much exacter
> results..)
> 
> Out for 4-5 hours - have to build a sub.. :-)
> 
> Carsten
> 
> Ray Keefer schrieb:
> >
> > Hi,
> >
> > The road scale at my recycling center is accurate to within 20 pounds.
> >
> > Regards,
> > Ray

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