No nexus card required - all the Nexus card does is make reporting easier (they have a separate telephone number and you do not need to have a passport with you. HOWEVER, if you want to make use of the Nexus reporting lines and cards ALL PERSONS on board must have valid Nexus cards. If anyone only has a passport, then you must call the regular Customs lines. A minimum of 30 mins and up to 4 hours lead time must be given as to your arrival at a reporting station (listed on their websites (US and Canadian Customs), you must provide, ETA, name and location of landing site, registration number and/or name of boat, full name, date of birth and country of citizenship of all passengers on board, destination, purpose of trip and length of stay for each passenger. The boat master will be given a report number for their records and must produce this number upon demand by US or Canadian Border Officers. If upon arrival a border officer is not at the specified landing site to meet the boat at the reported ETA or actual time of arrival the individuals who have reported may proceed to their intended final destination. (NOTE: This all applies to Nexus members and vessels - I would assume it is the same for passports, but you would have to provide all the passport details over the phone, as well, you can only make use of "telephone reporting sites" 1-888-226-7277 in Canada, and in the US may only arrive at "a physical reporting site" where the boat master must call Customs and Border Protection reporting number (http://www.nexus.gov - click on the "Pleasure Boats & Flyers" link on the left hand side of the page for the tele numbers).
Canadian Nexus telephone reporting: 1-866-996-3987
Canadian NON-Nexus telephone reporting number: 1-888-226-7277
US Nexus reporting number: see http://www.nexus.gov - click on the "Pleasure Boats & Flyers" link on the left hand side of the page for the tele numbers
From the Canadian Border Services Agency (CBSA) Marine rules (31 Mar 2010 ed)
"Please be advised that all private boaters are required to present themselves upon their arrival in Canada as per subsection 11(1) of the Customs Act (CA), the Presentation of Persons Regulation and subsection 18(1) of the Immigration and Refugee Protection Act (IRPA). This obligation exists regardless of their activities while outside of Canada and their planned activities while in Canada.
"Canadian boaters who enter foreign waters and subsequently return to Canada are obligated to present themselves to the CBSA as per the above requirement. This includes instances where vessels DO NOT drop anchor, land, tie up to a dock, enter an inland tributary or moor alongside another vessel while in foreign waters.
Similarly, all foreign boaters entering Canadian waters are required to present themselves to the CBSA regardless of WHETHER OR NOT they drop anchor, land, tie up to a dock, enter an inland tributary or moor alongside another vessel while in Canadian waters."
Hope that helps....