F5-10, or “Tenrater”, is the biggest sail boat, used in NAVIGA regatta sailing. The name stems from the fact, that there is some formula which uses the hull length and the measured sail area and which has to come up with a value of no more then 10.
F5-10 is a construction class, which means that everything not explicitely forbidden is allowed in constructing such a yacht.
Given the usual overall dimensions, Tenraters are very elegant boats with an enourmous speed potential. Their size requires a very different sailing style then what is e.g. required when sailing an F5-E boat.