Y25 Masthead Rebuild : The Ups and Downs

Jan 4, 2008
147
Yamaha Y25 mkII Long Beach, Ca.
Ok, what was planned for 3 days took 7 due to weather and extra time required figuring out how to stuff a 2 inch (50mm) 3/8 rope sheave into the space previously occupied by 1 inch (25mm) wire sheaves.
This all started when the jib sheave had froze up because of a lack of exercise due to using a roller furling headsail and rarely removing the headsail. Lesson learned- exercise your halyard sheaves regularly!
Fortunately , unlike many of the other Yamaha fitting being a one-off casting, the masthead is constructed of simple angle aluminum. Also of a great help was Garhaur Marine located locally in Ontario Ca. They found me the #25 captive bearing sheaves used to replace the original. The only real challenge was determining the sheave bore centers to result in the same exit location on the spar. Once that was decided it required minor hand filing of the mast extrusion to accommodate the larger sheave diameter. You'll note the stock head uses a third sheave to direct the main halyard toward the center of the mast. The larger 2 inch sheave didn't require the additional sheave.
As they say "a picture is worth a thousand words" so here you go!

CheersY25 standard wire sheave layout.JPG Y25 rope sheaves.jpg standard Y25 masthead.JPG the stuck sheave.JPG ,
Syntonos
 
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