A. Designer data, builder specifications and brochures, etc. are typically the best source. If necessary, the CRF Technical Committee can help with researching ballast data or even calculating it from measurements. To request help in calculating your ballast weight, complete as much of your CRF Application as you can, use our Data Inquiry Form to […]
FAQ Category: Hull and Underbody Questions
Q. I have a yacht with a centerboard, and none of the keel profile sketches displayed in the rating application show a centerboard. What keel type should I declare?
A. Check the box corresponding to the underbody profile that most closely resembles the fixed portion of your keel and your rudder type. CRF accounts for the effect of the centerboard via the declared value for ‘Draft Centerboard Down’.
Q. Why is the “Underbody Type’ declaration included in the CRF rating?
A. Stability and wetted area are critically important performance parameters, but it is not reasonable or practical to ask yacht owners to declare appropriate values for them. The 6 underbody types displayed on the CRF rating application work indirectly as surrogates for stability (via related keel volume, VCB and VCG), and more directly for wetted area. […]
Q. I have determined that the displacement of my yacht is heavier than that shown in the designer/builder specifications. How does this affect the other CRF data declarations that I need to make?
A. If you are declaring a displacement that is heavier than the designer/builder specification, it follows that your declaration for the LWL that corresponds to that heavier displacement should be longer, and that your declaration for Draft should be deeper, than the designer/builder specified values. One way to quantify the differences in LWL and Draft […]
Q. The only information that I have on displacement for my yacht comes from original design specification. How can I update that to a current ‘as raced’ weight?
A. Designers and builders typically provide displacement data referenced to the ‘design waterline’ that most often resembles a ‘light ship’ condition, with empty tanks and minimal food and gear. The weight added in equipping and provisioning for coastal cruising can increase that displacement by 10% or more. The boat hauling equipment in some yards can provide […]