If you're travelling to France from Jersey, your vessel needs to clear Customs and Immigration when you first arrive at a designated port of arrival. You need to notify the port authority at that designated port of arrival who will notify the relevant border officials.
If in exceptional circumstance your vessel does not arrive in France at a designated port, that port's authority must be notified to authorise your entry.
If you're a British national, you should have your passport stamped on arrival in France and on departure.
The most relevant designated ports (Points de Passage Frontalier or PPF) to Jersey are:
Carteret (Click here for form)
Dielette (Click here for form)
Granville (Click here for form)
For more information contact the relevant French port authority.
Declaration requirements for vessels' arrivals on Les Ports de la Manche website
For guidance on a list of border crossings, see page 21 of the Official Journal of the EU.