All skills concerning ocean travel fall under this category. Shipcraft encompasses the building and repair of ships, training of sailors, and navigation at sea. Further skills may be found through research. Study of these skills is not possible based simply on knowledge of the parent skill. Hidden Shipcraft skills, however, must be learned in other ways, even if the character has learned their entity numbers from other players.
Research is the more difficult choice.
However, to learn rare sub-skills there may be no alternative. Perhaps there are no players who already know the rare sub-skill, and so cannot record scrolls to instruct others. Or if there are, they choose to keep their knowledge secret. Research incurs a fee of 25 gold to pay for miscellaneous materials and costs. If research is successful, the new sub-skill will be added to the character's partially known skill list.