SAIL - - Rudder Failure -

There are five main ways that a rud­der can break and cause a boat to lose steer­age.

1. Rud­der stock fail­ure: The rud­der stock some­times fails when bend­ing stress in the stock ex­ceeds the strength of the ma­te­rial. With a spade rud­der, this usu­ally oc­curs just be­low the lower rud­der bear­ing, at the point of max­i­mum bend­ing load.

2. Rud­der blade de­taches from the stock: The blade can de­tach from the stock as a re­sult of sud­den im­pact, de­lam­i­na­tion or welds cor­rod­ing through. Rud­ders are of­ten built by weld­ing some pieces of stain­less steel per­pen­dic­u­lar to the rud­der stock. Foam is then lam­i­nated on ei­ther side of these “tangs” and fiber­glassed over. With time, stag­nant wa­ter in the rud­der can cause the stain­less-steel welds be­tween the tangs and the stock to fail.

3. Bear­ing/bush­ing fail­ure: Bear­ings can break down over time, es­pe­cially in steel bear­ing sys­tems when seals fail and salt­wa­ter gets into the bear­ing pack. Del­rin or other plas­tic-type bush­ings can also break down over time through ma­te­rial degra­da­tion or un­due fric­tion. If a bear­ing/bush­ing fails, the rud­der can seize com­pletely and/or tilt and bind, de­pend­ing on your course and an­gle of sail.

4. Rud­der bind­ing: Rud­der blade bind­ing is typ­i­cally caused by fish nets or lines that be­come wedged be­tween the rud­der blade and the hull.

5. Hull de­for­ma­tion or crack­ing: In some rare cases, rud­der fail­ure may be caused by hull de­for­ma­tion or ma­te­rial fail­ure around the rud­der bear­ing mounts. While the least com­mon fail­ure mech­a­nism, it is also the most dif­fi­cult to re­pair.

Of course, the best emer­gency rud­der sys­tem is the one you never use. So, given these fail­ure mech­a­nisms there are a few things to check to make sure the rud­der is in good op­er­a­tional or­der. These in­clude look­ing for:

• Pit­ting, cracks or cor­ro­sion of the rud­der shaft at joints and es­pe­cially where it en­ters and ex­its the hull

• Mois­ture in the rud­der blade ma­te­rial: use a con­tact mois­ture me­ter or drill a small hole in the rud­der blade and check for wa­ter

• Cracks or craz­ing on the sur­face of the rud­der blade, which could sug­gest hid­den flex­ing of the rud­der post

• Any dam­age in the bear­ings or gud­geons, in­clud­ing the pin­tles at the foot of a non-load­bear­ing skeg

• Cracks or de­for­ma­tion of the hull around the rud­der, in­clud­ing cracks in the bot­tom paint or gel­coat, since these could be a sign of more se­vere prob­lems

• Move­ment or de­flec­tion of the blade, shaft or bear­ings when the rud­der is pushed in any or all di­rec­tions

This rud­der sus­tained se­ri­ous dam­age in the course of a hard ground­ing off Fiji

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