To do that in Greece the skipper has to provide a valid sailing certificate proving his/her competence. There are some countries that do not issue sailing certificates. In any case, there is a requirement to present a reference from your yacht club verifying your ability to sail or a sailing resume or anything that help us understand your sailing level experience. The co-skipper will be asked to complete and sign an official self-declaration form, stating their sailing competence. Charter companies and/or owners and fleet operators hold the right to test your sailing abilities before charter.