Certification of a vessel to carry passengers for hire involves a number of steps.  When building a new vessel, the plans must be approved before the build starts. Sufficient structural analysis, using one of the classification rules (I use American Bureau of Shipping) must be used to demonstrate that the construction meets scantling standards. A preliminary stability analysis is also required using applicable parts of 46 CFR (Code of Federal Regulations), in this case parts 166 to 199, Shipping. Before the build starts, the builder, or owner, submits a “Request for Inspection” form with the USCG local office, so that a project number and inspector can be assigned to the project. Liaison services, on some level, will be needed during the build, depending on how complicated the vessel is. Arrangement and equipment must comply with the CFRs. Inspection oversight will be given at various intervals by the assigned inspector. An engineer at MSC (USCG Marine Safety Center) in Washington, DC, will also be assigned to review all submissions for approval.

Small passenger vessels—T Boats, under subchapter T of 46 CFR SHIPPING – are given approval to operate in various levels of exposure. Lakes, Bays and Sounds is the route expected with the lowest level of exposure, followed by Partially Protected Water and Exposed Water Routes. Each carries limitations of distance from a safe harbor of refuge and stability requirements. The number of passengers allowed aboard influences the equipment required and the amount of subdivision (water-tight bulkheads) within the hull. The passenger divisions start at no more than 6 (six-pack) which does not require inspection. The next level is up to 49 passengers, and then, up to 149 passengers for wood vessels, which requires full plan approval and inspection to CFR standards.

After the vessel is complete and launched the next phase starts. This phase is to demonstrate the vessel complies with stability standards and the crew complies with qualification and ability to handle the vessel. For stability, a Dead Weight Survey (DWS) is performed to determine the lightship weight of the vessel. A DWS procedure and schedule of events (of the day of survey) must be submitted and approved prior to the survey. MSC, Washington will then request that the local inspector witness the event on the scheduled day. The owner or representative (Marine Surveyor or Designer/Naval Architect) will conduct the survey and submit the results to the designer or whoever is performing the calculations. Using the lightship weight determined by the survey, the final stability analysis is made and submitted to the USCG. Stability analysis can be performed in either of two ways; calculations or by an incline test. Next, the vessel is scheduled for a ‘COI’ (certification of operation inspection). The inspector will go along as witness on the ‘check ride’ of the vessel, which may include retrieval of a man overboard. The operator must have a valid captain’s license and the crew must be familiar with the vessel.

After passing all the prior inspections and tests the vessel will be issued a Stability Letter. This is the official approval to carry passengers for hire. The local USCG will also issue a letter describing the approved route and operating area. The USCG will schedule periodic routine inspections the vessel as mandated by the local inspection office. They are usually every 18 months during haul-outs. The type of hull inspection will vary with the hull construction method.

 United States Coast Guard has approved a dozen of John Marples's plans to carry passengers. Starting with a pre-certified design reduces the cost of the certification effort. Click here for more information.



In the past 20 years, John has completed USCG certifications to carry passengers for hire on more than 30 multihull vessels. The boats ranged from 32’ to 64’ and from 16 to 149 passengers, both catamarans and trimarans. Most of the vessels were original builds, with drawings from this office that were submitted and approved by the USCG in Washington, D.C. Other vessels were designed as pleasure boats by other designers and were structurally modified by John to qualify for certification. One power catamaran had no design information and so John measured the boat, made drawings that were approved by the USCG and then completed the certification. John is glad to offer his services to help multihull owners and builders provide liaison to the USCG during construction, or for existing vessels, and prepare all document submissions to the USCG to gain approval to carry passengers. Please call for consultation about your vessel and estimated costs.