The Royston Grange hit a products tanker, loaded with petrol. Her intakes for the air conditioning system pick up and suck in the released petrol vapour from the tankers evaporating cargo, this ignited the vapour inside the Grange. Very tragic accident as they found burnt skeletons on burnt out bunk springs, after the aciddent, the MCA issued a M notice advising ships to have fitted in their bridges crash stops for the ventilation and in event of a collision to immediately crash stop the system. As previously said all gas boats as well as chemical boats are specially designed for the cargo and have a good safety boat. I know of one which steamed between the Sunk Fort Towers in the Thames estuary, she completely demolished the Towers and survive with no loss of cargo. I have heard it said if a tanker did leak the sea around her would freeze for some considerable distance. The only real danger with them as with all gas transport systems and storage tanks is a blevy happening. if you see one run like hell, the bang is worse than a shedful of TNT going off.