1-954-727-3570 info@horizon-na.com

Regulatory compliance services still remain a critical and ongoing part of the marine industry, regardless of the circumstances. With vessels being stationary in the water, it presents the ideal time to carry out a compliance procedure such as a lightweight survey. A lightweight survey is a regulatory compliance assessment required to be completed every five years. Recently, we’ve been providing increased compliance management services such as lightweight surveys.


A lightweight survey is an important compliance procedure for not only commercial yachts but also highly recommended for private yachts. As a yacht changes and grows, it can become overweight. Activities such as removing and adding equipment can compromise stability. Even the smallest of changes can really add up. Safety is the priority, but also, if results are outside of approved limits, it can limit tank capacity and the vessel’s range. ​ A regulatory compliance assessment is not only necessary but getting it done early can save you time and money. For instance, performing a refit, without evaluating lightship characteristics and doing a weight study isn’t a good idea. It’s critical to determine the impact to a vessel’s load line and stability booklet prior to a refit. This single activity can potentially save millions in cost, and months in time out of service.

Generally, these surveys can be described as an audit of all of the items aboard a vessel which are to be added, removed, or relocated to calculate the lightship condition. Lightship weight, longitudinal center of gravity (LCG), and transverse center of gravity (TCG) are each recorded by checking them against the previous stability booklet.  The lightship weight is the actual weight of the vessel without fuel, passengers, water, and so on. The center of gravity of each item or tank is calculated based upon survey notes, general arrangement, structural drawings, and tank tables.

After the survey is completed, a report is developed and delivered. Essentially, the obtained lightweight particulars of the vessel will be compared against the results from the previous stability booklet. The change in lightweight displacement must be less than 2% and the change in LCG over length between perpendiculars (LBP) must be less than 1% in order to accept the use of previous lightweight particulars. If the survey results say that the vessel is outside of the approved limits, the recommendation will be made for a new stability test. 


There are several steps to prepare the vessel for this compliance procedure. The list of documents that need to be provided prior to the survey include: a general arrangement, tank capacity plan, tank tables, a profile drawing, drawings of transverse sections, and a previously approved stability booklet which contains lightweight particulars.

Additionally, the vessel should be in complete condition. There should not be any ongoing work performed onboard and excessive trim or heel should be avoided. As well, the crew and personnel onboard is to be at a minimum. Finally, the survey needs to be done during relatively calm weather as winds, waves, and currents can significantly impact the freeboard measurements taken during this survey.


This may be a perfect time to complete the necessary compliance requirements. Special survey windows allow for lightweight surveys to be completed early, up to one year in advance, without changing the date of the next one due to be completed in the future.

As mentioned earlier, if you are planning major modifications to the yacht such as a refit, a lightweight check or weight study is strongly recommended prior to doing so. It’s better to be proactive as unchecked changes to stability can prove to be a costly and lengthy endeavor. The mere thought of having to rip items out of a refitted boat not only causes undue stress but wastes valuable time and in some cases, can cost millions of dollars. A small investment in doing a lightweight check can be the difference. Knowing how the boat will sit in the water should be determined hand-in-hand with performing a refit.

If you are interested in learning more about regulatory compliance management services, Horizon Naval Architects is happy to assist. We are located at 760 Taylor Ln. #2, Dania Beach, FL 33004 and can be reached at 954-727-3570. You can also email us at info@horizon-na.com