1. Those are ships that stopped at islands in the Atlantic. Since the data was copied from ships' logs I doubt there is data on ships that went down. 2. It see

1. Those are ships that stopped at islands in the Atlantic. Since the data was copied from ships' logs I doubt there is data on ships that went down. 2. It seems that the person that entered the data just entered a limited data set. So no this does not represent all shipping. 3. I am pretty sure this is related to islands the ships are stopping in as well. (Probably Georgetown and St Helena).