Adgan, Phenergan are the common brand names, available as injectable, oral and rectal.
In my opinion, the rectal would be advised for cruisers, injectable- do not really want to mess with needles as the boat rocks and rolls, and with oral, the vomiting associated with motion sickness you might not get the full dose and has a slower absorption rate (takes longer to work).
The wonder drug for motion sickness when the insertion of second digit deep into oral pharyngeal cavity fails to resolve the symptoms.
Other uses include - Allergic Reactions, Anaphylaxis Adjunct, Apprehension, General Anesthesia Adjunct, Motion Sickness, Nausea and Vomiting, Pain Treatment Adjunct, Prevention of Post-Operative Nausea and Vomiting, Sedation as Adjunct to Anesthesia, Sedation in Obstetrics, Transfusion Reaction Urticaria.
Side effects - Anorexia, Blurred Vision, Dizziness, Drowsiness, Dry Nose, Dry Throat, Dysuria, Excitement, Fainting, Hyperhidrosis, Hypotension, Impaired Cognition, Irritability, Nervousness, Nightmares, Skin Photosensitivity, Skin Rash, Tachycardia, Thick Bronchial Secretions, Tinnitus, Visual Changes, Xerostomia
Important to note is the "impaired cognition." For many patients this would be comparable to many glasses of wine.