› Pre-2022 Etchells Class Rules › F.4.1 (Boom extrusion) Materials › Reply To: F.4.1 (Boom extrusion) Materials
After a little more searching, the HV-90WP possibly could be a hardness measurement. A hardness measurement can be used (in conjunction with other more complicated tests) to verify that an alloy is what it is supposed to be. So, maybe the HV-90WP is not an alternate alloy, but a qualifier for the specified 6061-T6 alloy. The specified designation (HV-90WP) is not one I have found, but it could be a format used in the 1960’s when the rules were first written, but which has since changed. There is a hardness designation called a Vickers Hardness, which is abbreviated HV, and it has a value of 107 for 6061-T6. Maybe one of the class graybeards has some insight.