A water jet propulsion apparatus having a duct forming a channel, an impeller disposed in the duct, a bearing of the impeller provided in the duct, and a cap closing the rear end of the bearing. In addition, at least one stream-straightening groove is formed in an external face of the cap. In the internal...http://www.google.com.au/patents/US6840826?utm_source=gb-gplus-sharePatent US6840826 - Water jet propulsion apparatus
