Originally Posted by carstenb
Here's the formula for change in immersion with added load.
T = L*W/120 =[t/cm]
L*W = length (waterline) X
width (waterline), all in meters and decimal parts
Change in immersion
(Δ)dm = q/T [cm] q= added load in metric tons, T(cm) from formula above)
New immersion- dm,2 = dm,1 ± q/T*100 [immersion in meters and Load q in metric tons]
On our boat 12meters by 4 meters (I've just rounded off to make all this easier), adding 2 tons of load means:
T=12*4/120 = 48/120 = 0.4 (tons per centimeter of change in immersion)
2 tons therefore = 5 centimeters change in immersion
I've just revisited this thread...using 120 in the first line suggests a coefficient of fineness of about 8.33... sounds more like a VLCC than a yacht.
I think a CoF in the order of 0.6 would be more like it in the case of a yacht.
That would give in the example above ( 12 x 4 x 0.6 )/100 a TCPI of .288
So loading 288 kilos would sink the sample yacht by 1 cm. 2 tonnes would sink her 7 cms.
Still not a lot IMNSHO.
More info here for them as cares Stability
Anyone really wanting to know the waterplane area of their boat should use Simpson's Rules... Ship Stability for Masters and Mates - Bryan Barrass, Capt D R Derrett - Google Books