[1] This occurs, for example, where the ship needs urgent repairs during the course of its voyage or some other emergency arises and it is not possible for the master to contact the owner to arrange funds, allowing the master to borrow money on the security of the ship or the cargo by executing a bond.
With bottomry and catastrophe bonds, you receive a loan up front and only pay it back with a premium if the risk event doesn't occur.
Demosthenes's speech Against Zenothemis accuses the titular shipper of the first type of fraud in the fourth century BCE.
[2] In his Life of Cato the Elder, Plutarch describes how he would use the process to make money, but calls it "the most disreputable form of money-lending".
It is an arrangement that is easy to describe but difficult to characterize: not a pure loan, because the lender accepts part of the risk; not a partnership, because the money to be repaid is specified; not pure insurance, because it does not specifically secure the risk to the merchant's goods.