10 Rater

10 RaterBoats in this international class are not limited in length and have overhangs beyond their waterline endings making them light, sleek, seaworthy and fast. This IRSA international rule is based on the 1887 ‘length and sail area rule’ which allows short waterline length boats to have a big sail area and longer LWL boats have smaller sails. It is an ‘open’ rule with great freedom to develop design and construction, particularly in rigs and sail plans.

Any boat can be a 10 Rater and several Marbleheads have been successful in the class by conversion with just one larger rig giving 40% extra sail area. A typical 10 Rater is approximately 1600mm long, with a water line length of approximate 1500 mm,  weighs 6kg and carries one square metre of sail.

Like the Marblehead, the open rule with its “no limits” approach has resulted in escalating costs  resulting from the use of advanced materials  and multiple rigs. This once numerous class is now much reduced and again like the Marblehead, there exists the opportunity to revive the class in a restricted vintage form.

IRSA 2016 Class Rules Measurement Forms and Certificates

Attached are the full set of updates for the 2016 Class Rules Measurement Forms and Certificates.


Release notes for class rules for 2016 – Marblehead, Ten Rater & A Class

Notes to introduce the revised class rules and indicate the significant changes and their rationale:


2016 Class Rules Release Notes for Official Measurers and Certification Authorities

Attached is a detailed explanation of the changes in the updated Class Rules specifically focused on the needs of the Official Measurers and Certification Authorities.