Ship was a crude oil tanker. Ship was sailing towards Singapore. On a fine evening, one of the boiler circulating pump which was running tripped off Changed over the stand by pump. The very next day morning the stand by pump also tripped off . as the vessel was in Malacca straight, the ship’s speed was not reduced. After 20-30 minutes, it was found the boiler water level came down very fast, and when opened the exhaust drain found lot of water coming. Ship’s speed reduced to slow as it was approaching Singapore and there was a heavy traffic . The ship reached Singapore, and got the work shop assistance to plug the holed tube.