There are severe penalties for not following homeland security
Good info can be found here
What procedures must a small boat follow when entering the United States?
The master of a pleasure boat must report to U.S. Customs
and Border Protection (CBP) immediately upon arriving into the United States from a foreign port or place and must provide a formal vessel entry on CF 1300 within 48 hours. He will also need to report any foreign merchandise on his boat that is subject to duty.
CBP has implemented the Small Vessel Reporting System (SVRS) for information visit CBP.gov. If reporting with SVRS see SVRS Application to enroll. Questions about SVRS can be directed to 800-432-1216.
Cruising licenses exempt pleasure boats of certain countries from having to undergo formal entry and clearance procedures and can be obtained from the CBP Port Direct at the first port of arrival in the United States. U.S. pleasure craft and foreign-flag vessels without a cruising license
, which are 30 feet or longer in length, must pay an annual fee of $27.50 for the user fee decal. User Fee Decals may be purchased online through the CBP Web site.
U.S. citizens should carry proof of citizenship such as a passport or birth certificate. Canadian citizens should present proof of Canadian citizenship; Mexican citizens may present a border-crossing card. Canadian, Mexican, and U.S. citizens must carry a passport if they are arriving in the U.S. from outside the Western Hemisphere.
If your boat has anchored or tied up, you are considered to have entered the United States. No one shall board or leave the boat without first completing customs
processing, unless permission to do so is granted by the CBP Officer in charge. The only exception to this requirement is to report arrival. If it is necessary for someone to leave the boat to report arrival to CBP, he or she must return to the boat after reporting and remain on board unless instructed otherwise. No one who arrived on that boat may leave until the CBP Officer grants permission to go ashore. A report of arrival into the United States should be made to the CBP office nearest to your point of entry.
A comprehensive guide can be found here: Pleasure Boats.
A listing of ports
of entry and their phone
numbers can be found on CBP's Web site