> At the same time, we would never know to send one in time to begin with, right?
Well, we'd know right up until the moment the iceberg was avoided. At that point, all memory of the disaster would be lost and we'd suddenly find ourselves in 1912 with no idea of how we got there and, worse, no memory of having time traveled and therefore no real way of getting back. Unless we were being monitored by someone in 2005 who had the means of bringing us back, we'd be stuck.