More than a third of the assaults occurred in passengers' own cabins - often after crew forced their way into the rooms.
Dr Poulston said the data used mostly involved American and Canadian incidents but warned the lessons learnt were just as relevant to New Zealanders.
"While cruise vacations are often sold as voyages of romance and adventure a significant number of passengers have very different and very unpleasant experiences," she said.
Based on data from Royal Caribbean International (RCI) and Carnival Cruise Lines, the research found "the rate of sex-related incidents on cruise ships is almost 50 per cent higher than the rate of sexual assault on land in Canada".
RCI - which has a ship arriving in New Zealand for the Rugby World Cup - did, however, show a considerable improvement, dropping its rate of alleged incidents from nearly 112 per 100,000 passengers in 2003 to 45 in 2005.
Dr Poulston believes one reason assaults are so high on cruise ships is the fact passengers arrive on board and let their guard down.
Examples of sexual assaults given in the research varied from a 14-year-old girl who had been kissed and inappropriately touched by a second officer through to a woman who was raped in her cabin by a steward.
A spokeswoman for Royal Caribbean International, which also owns Celebrity Cruises, said the company's highest priority was to ensure the safety and security of all its guests and crew members.
"This is always the case - whether it is a regular cruise or a chartered cruise like Rhapsody of the Seas' sailings during the Rugby World Cup in NZ."
She said the company carried more than 4.5 million guests and crew members in 2010 and reported 13 allegations of rape and 11 of sexual assault - not all of which were upheld.
A spokeswoman for Carnival Australia, which operates P&O Cruises Australia and New Zealand, said claims of sexual assault on board its ships were extremely rare and there was no data to suggest assaults of any kind occurred at a higher rate on its ships than on land.
"Our responsibility is to create an environment on board our ships where we do all we can to make sure people are safe, that behaviour is appropriate and our passengers enjoy their holiday."
OCEAN PREDATORS
Cruise ship attacks:
* New Year's Eve 2007: A 46-year-old Aucklander claimed she was raped on the Pacific Star by a man she had been drinking with. No charges laid.
* Australian mother Dianne Brimble died on a P&O cruise in 2002. Her naked body was found in the cabin of four men. She had overdosed on the date-rape drug Fantasy.
The research:
* Royal Caribbean International - 18 ships and 451 complaints of sexual assault and harassment between 1998 and 2005.
* Celebrity Cruises - 9 ships and an average of 16 complaints each year between 1998 and 2002.
* Carnival Cruise Lines - 92 sex-related incidents in the year to September 2008, including 48 of sexual contact, 40 of sexual assault and three of sexual harassment.
