That was neither a rule nor a tradition, but often case a suicidal matter in the days of merchant vessels of the 17th and 18th century: The captaincy contracts of the days, enforced by the insurers of the commercial trip had specifications that the Captain was responsible to the investors for the value of the ship, should anything happen to it, but was exonerated if he failed to come back himself. Considering the rules that also made him and all the other members of the family subject to jail time for debt should he be unable to pay his debtor, many captains chose suicide to save the family fortune.