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-   -   Rudder Failure (http://www.sailnet.com/forums/gear-maintenance/21225-rudder-failure.html)

jimthom 08-05-2006 07:02 PM

Rudder Failure
 
Besides a collision with some underwater object, what sort of extreme forces could cause a skeg-hung rudder to fail? Does reversing with the motor cause a lot of pressure on the rudder? Or slamming in reverse down a wave? What action could cause a rudder to come up hard against the rudder stops? Could this be enough to cause rudder failure?
Cheers, Jim

sailingdog 08-05-2006 07:59 PM

Reversing at higher speeds creates tremendous pressure on the rudder, as does slamming down a wave in reverse, and either could cause the rudder to slam into the stops. That may cause damage to the rudder, but I doubt that it would cause a rudder failure after a single occurrence unless there were some other underlying problem.

Corrosion may have weakened the rudder post.

camaraderie 08-06-2006 10:05 AM

Jim...it would be helpful to understand the type of boat and nature of the failure. But sailing dawg is right about the tremendous forces that can be exerted in reverse or by wave action.
One possibility is water seepage into the rudder foam/laminate and then attacking the stainless post/grid which can corrode quickly in anerobic conditions causing failure. Delamination is another possibility especially if there was water in the rudder and it was stored on land in freezing conditions during the winter. If either of these conditions existed, then just a bit of heavy pressure on the rudder could have broken things loose.

sailingdog 08-06-2006 11:00 AM

Ahh, yes, delamination...or even rot, in the case of wooden rudders... are one I missed pointing out. :D

hellosailor 08-06-2006 06:52 PM

And there are some boats (the Beneteau First 38) where the stock rudder was deeper than some stock keels, so it was possible to ground on the RUDDER and damage it with no keel damage.

A lot of rudder failures trace back to corrosion damage from hairline cracks or other problems that allow water into the core, then the armature and tube just up and fail one day.

sailingdog 08-06-2006 07:37 PM

Why would anyone design a boat with a rudder that is deeper draft than the keel? IIRC, the Beneteau First 38 has a fin keel and a spade rudder.... that's just irresponsible. It is doubtful that a spade rudder will ever be strong enough to withstand a grounding—so protecting it by making it the same length or shorter than the accompanying keel is the only sane solution.

hellosailor 08-06-2006 07:52 PM

"Why would anyone design a boat with" Damfino, it wasn't on MY watch.<G>

Could be someone said "We've got a stock rudder that will work for that design" or even just "Yeah, we can make a shoal draft version of that." Then again, it might be part of the same french engineering that leads some folks to call them "BendyToys".

I like some of the boats...but overall I wish the French would stick to champagne and cheese, they do THOSE so nicely. Coq au vin, lots of nice things from France that don't need machine tools to make them.<G>

sailingdog 08-06-2006 08:01 PM

Never doubt the bravery of the French, they discovered snails are edible. But that should make you doubt their intelligence. :D

hellosailor 08-06-2006 08:10 PM

I don't doubt their, ah, bravery. I admire the way champagne comes in those nifty single-serve portion controlled bottles, too. I'm just glad they never quite figured out how to make locking bails on them.<G>


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