The Portsmouth ferry is a conventional ferry and takes ten and a half hours to make the journey to St. Helier port in Jersey. This may sound like quite a lot, but there are amenities on board, including a bar, a restaurant and a shop, to take your mind off the journey. Then there are the fantastic views from the top deck, of England's shoreline disappearing into the distance, the expansive majesty of the sea and then the lush green hills and forests of Jersey. Then there is also the cheaper price of tickets to consider. Lastly, it also has the most consistent timetable, running six days a week (not on Sundays) all year round. Ferries leave Portsmouth in the morning at 9am and returns from St. Helier at 9pm, although these times may of course be subject to amendment by the operator.
The Poole and Weymouth ferries are actually high-speed catamarans, whisking you from England to Jersey in three hours fifteen minutes and three hours twenty five minutes respectively. Both services run six days a week during the on-season, excluding Tuesdays, which Condor uses to service the ships (and may be subject to change). During the off-season, the Poole-St. Helier route is removed from Condor's schedule and the Weymouth-St. Helier route is scaled down to two days of operation - Mondays and Fridays. The departure times, when there are ships operating, remain fairly constant; leaving England at 11am and returning from Jersey at 6pm, although once again these may be subject to change.
To keep up to date with the most recent time/date changes, the best thing to do is visit Condor's webpage at condorferries.co.uk or by calling their automated information line on 01202 207216, which is updated with all the latest travel information.
Should you be travelling from the continent, or wish to take a day trip, Condor Ferries have boats travelling all year round between St. Helier and the beautiful medieval coastal city of St. Malo, famous for its fortress, its impressive walls, its old buildings and some of the best seafood (including local oysters) restaurants around. The boat leaves St. Helier at five to twelve, only taking an hour and twenty minutes and returning at five in the evening (or, if you want to stay the night) at eight in the morning, Thursday to Monday. Manche Iles Express, a French company, also has regular boats running to Barneville-Carteret (a picturesque coastal commune) and Granville (a quaint harbour town) during the on-season; they do not run at all from October to April. All three of these towns are within easy driving distance of one another so, on a longer trip to Jersey, it is more than possible to take a long weekend from your time there to go and explore them (even during the off-season, just depart and return from St. Malo).
As a foot note, it is not necessary to carry a passport with you if you are taking the ferry to Jersey. The British Nationality Act of 1981 means that Jersey is officially part of the UK. However, considering recent security problems and especially if you're planning to travel to France, it may be an idea to bring it with you anyway (although any photo ID, such as a driving license or any official ID issued by the government, would also suffice).