Stability of tea and coffee cups on the Islay ferry

I had a coffee (left) and Mrs B had a tea on the Finlaggan as we came home through another stormy sea! Same volume of liquid but two different drinking vessels. Stability is when the line of action of the weight acting vertically downwards from the centre of mass of an object still passes through the base area. The tea cup has a higher centre of mass and has a narrower base area so it can't be tipped sideways by as big an angle before the the line of action of weight passes outside the base and the cup tips over. However the stabilisers on the ship worked really well and there was no chance at all of the cups tipping.