Waterline weight calculations

[Trout58]

Hi All

Does anyone have proven methods/calculations for determining how much a model ship needs to weigh to sink it to its scale waterline please? I have read bits and pieces here and there that imply it is not to complicated once you have certain data from the actual ship including the block coefficient?

Any guidance would be very appreciated, thanks

[EJFoeth]

Well, if you know the displacement of the ship at a given waterline, you can calculate the weight of the model. It's simply the displacement of the ship divided by the cube of the scale factor (factor*factor*factor).

Now, I guess you are going to sail in fresh water, so you need to have a weight that's about 2.5% less if you want the same waterline. You do not need more information than that.

From the block coefficient: this is a volume coefficient and not a weight coefficient. With a water density of 1 kg/m^3, it's simply

block coefficient * waterline length * submerged maximum beam * submerged maximum draft / scale ^3.

[Trout58]

Thanks for your reply