Discussion on Ross et al: “Damage Stability Characteristics of Model RO/RO Ferries”

Abstract

I have read this paper with great interest. The following observations may be of interest. It is correct that the Estonia sank in about 40 minutes, but if it was caused by water collected on top of the car deck as suggested in [1] is not certain. Reference [1] actually says that water started to come in on the car deck at 01.14 hours, when the ramp was dislodged by the loose visor, and that small amounts of water started to enter, resulting in a 3-dug list. Then it is suggested that the visor fell off at about 01.15 hours, pulling the ramp fully open and allegedly larger amounts of water came in--250 tons/minute--resulting in a sudden 15-deg list. Then the water inflow stopped--the list was constant for several minutes--which enabled about 300 persons inside to evacuate the ship to open deck no. 7. Finally, more water allegedly started again to enter on top of the car deck so that the list increased, but the vessel never capsized, which you would have expected. With 2000 tons of water on the car deck you would have expected that the ship would have turned turtle and floated upside down. The inflow rate is not clear in [1]. One calculation (supplement no. 522) says it took 28 minutes for 2000 tons to enter, another (supplement no. 523) that it should have taken 2 minutes--in both cases the ship capsizes.