Comedians on cruise ships love to joke about them. Light sleepers frequently gripe about them. And for years they’ve been a mainstay of the cruise experience. But the explosively loud vacuum toilets found on cruise ships may soon be a thing of the past.

Finland-based Evac has unveiled what it’s calling the “most silent vacuum toilet on the world market” — one specifically designed for cruise ships. The Evac 910, it’s called.

“We have put a lot of research and development effort into reducing the sound pressure level,” Evac sales executive Markus Peltola tells industry watcher Seatrade Insider this week. “With this toilet a major source of annoyance to passengers has been eliminated.”

Indeed, Peltola tells Seatrade Insider the Evac 910 is no louder than comparable gravity toilets found on land (A statement posted on the Evac website says the sound created by the model is about five to eight decibels lower than that of other cruise ship toilets).

Seatrade Insider also quotes Peltola as saying more than 4,000 of the toilets already are on order for Royal Caribbean’s Allure of the Seas, to be delivered in 2010.