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Old 24-10-2014, 18:50   #31
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Re: Rudder Failures

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Originally Posted by Ex-Calif View Post
<edit> Here's an idea. If the AP stresses are correlated to hydraulic pressure or to amps (for an electric) I bet a simple idiot light near the helm could be installed and calibrated to light up when AP stresses are "high" - That would be an interesting clue that the AP and structure were taking a beating.
If one cannot tell without idiot lights when the forces on their AP are getting high, then one has not sailed much with their AP.

Besides, in a properly engineered system, the fuse should pop before the mounting bracket.

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Old 24-10-2014, 20:10   #32
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Re: Rudder Failures

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Originally Posted by colemj View Post
If one cannot tell without idiot lights when the forces on their AP are getting high, then one has not sailed much with their AP.

Besides, in a properly engineered system, the fuse should pop before the mounting bracket.

Mark
Don't disagree about understanding the forces without a light but there are systems, especially hydraulic, with very little feedback.

100% on the AP disconnect before the boat breaks.

However, haven't we seen enough aftermarket (or factory) below decks AP mountings that are weak to know this isn't always the case?
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Old 24-10-2014, 21:45   #33
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Re: Rudder Failures

I wouldn't necessarily assume that hand steering is always going to be appreciably gentler on the rudder than the AP. I would guess that the rudder installation design is usually far more well thought out than the AP mount design. AP failure doesn't indicate anything about rudder integrity.
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Old 25-10-2014, 02:02   #34
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Re: Rudder Failures

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Originally Posted by JazzyO View Post
The people onboard tell a different story - who are you to say they are lying? The rudder post casing (? terminology? sheath?) failed at the Cape Verdes about 1000 miles after delivery in Hamble. It was due to wear, the boat didn't hit anything. The leak was unrepairable and the boat went down. Fortunately no lives lost.


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I was being facetious I have no quarrels with your statement.
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Old 25-10-2014, 02:09   #35
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Re: Rudder Failures

SmackDaddy,
When you are steering in larger seas with a spade rudder and it stalls, the loads actually go down on the rudder, they are less.

As a general statement....a spade rudder is the most effective rudder for steering a sailboat. If production builders built spade rudders like Steve Dashew did I doubt we would even be having this discussion.
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Old 25-10-2014, 15:08   #36
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Post Re: Rudder Failures

Before I explain a few things on rudder design, construction, failures and the why. Here's an infobit sailorboy1. For a LARGE percentage of deep ocean races; now & in the past, carrying a viable emergency/backup rudder has been mandatory as dictated by various race governing bodies. Such rules came about as rudder, & steering failures are close to the #1 reason why boats had to withdraw from races part of the way through, & call for assistance... mid-ocean. The blades just spinning on the shafts like pinwheels.

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Originally Posted by sailorboy1 View Post
Pretty big statement. What engineering and design analysis for this do you have?
I'm not certain as to whether you're asking for my background in engineering & design. Or why I made some of the statements that I did, regarding rudders.

Formal schooling - BS @ US Naval Academy, in addition to some graduate stuff. Including in Naval Architecture, & boat design & construction.
Informal - Beating the stuffing out of, & then repairing some of the top racing yachts in the world for a few decades. Even including the America's Cup, one in which I was hunted down, & asked to skipper a boat (with no job searching to participate in that race then, by me).

As an example of what "beating the stuffing out of" means. On one of the Maxi's I raced on, boats with sails which weighed in around a quarter ton each. We were doing a distance race, & several times a day (on bad days) the tail end of the vessel was pushed around enough by the waves for us to jibe, all standing, flying the storm kite & full main, in 30 - 40+ knots of breeze.

And primarily, it was just us, the core crew who did 95 percent of the care of the vessel. Not counting things like X-raying key rigging parts, or rebuilding engines.


As to rudders on production boats, & their design & construction. Let's start with the shaft. It may or may not conform to ABS rules (regarding size/strength), albeit said rules are not really sufficient when it comes to such things.
I say this, as for example (going off of memory), I believe that the Dashew's specify that the shafts on their sailing vessels to be built to 4x ABS rules at a minimum; although it may be 6-8x. No Joke.

Shafts, part II: When you install a thru hull in a boat, it's bedded into a flexible sealing compound. Both because hulls flex, and also because the various materials involved expand & contract at different rates.
- I can't say that I've seen much in the way of proper sealing of rudder shafts where they enter the blade, on your run of the mill boat. Such a seal doesn't need to be of the same type as on a thru hull. But there needs to be a SERIOUS connection there, and it must be waterproof. And durable enough to ABSOLUTELY maintain it's seal throughout, literally, tens, & hundreds of millions of cycles.
Few rudders meet this qualification, which is why it's not at all uncommon to see a small river pour out of a rudder when a hole's drilled near the bottom. Not an unusual test during a thorough survey.

Also, I've been sailing along on a vessel where all of a sudden we did a couple of quick 360's (with a kite & main up, Force 5). And when I look back, getting ready to ask the helmsman WTF in a rather direct & forceful manner. He too is looking back, & when I follow the sight line out to where he's looking, there's the bottom half of the rudder, bobbing up & down on the waves like a Styrofoam beer cooler lid.

Upon inspection of the rudder, there was massive water intrusion around the holes for the pintles & gudgeons. And a few phone calls, including to the builder, yielded the fact that such was a well known weak point in the boat/rudder (yes, including by the boat's builder).

The thing is, there was ZERO blocking, or extra reinforcement of the rudder in the vicinity of the bolt holes/pintles & gudgeons. Nor was there any sealant. Just some fiberglass skins, & a foam core.

On bigger boats, with a shaft, as alluded to above. Where water also penetrates these rudders. If one looks at how the structural framework of the rudder is spec'd out, & built, you'd KNOW common sense was dead.
There are production boats where the framework welded to the Stainless Steel shaft is... Cast Iron plating. And no, I'm not kidding.

Even on boats where the structural framework is Stainless Steel, the welds are often done with mild steel welding rod. And no special work is done to protect the welds after they're done. The thinking being, that the skins will keep out the water, so there's no need.
Also, often enough, the blades, or whatever is acting as framework in a rudder is simply welded in place. There are no slots machined through the shaft for a piece of plate, in addition to welding it. So all of the load is directly on the welds holding the framework to the shaft. And not at all in a direction where welds are at anywhere close to their strongest.

So, let's say, for argument's sake, that all of the metal used for the rudder's framework & shaft, is Stainless Steel. And we'll give the builder the benefit of the doubt that all of it's 316 or a similarly, more corrosion resistant alloy than 304/306.
- Keep in mind that putting Stainless Steel into water, or a moist environment with little oxygen is the definition of the recipe for crevice corrosion.
So that even when proper rod for welding Stainless is used, when you put it into this environment, you're asking for trouble. Ditto for the shaft & blade material.

If you take a look at Stainless hardware topsides. Most of it's polished almost to a jewelry finish. And many critical fittings are passivated on top of that. All of this being done, to prevent corrosion. Yet these Stainless fittings only get a good splashing on a semi regular basis. Not immersion 24/7 for life as is the case with rudder parts.

Some forms of stainless do work well for underwater applications, if chosen suitably for the task. Witness Aquamet/Nitronic 50 used for propeller shafts. Yes, there are better metals out there for the job, but it's passable.

Also there are ways of bonding fiberglass composites directly to some metals, including some alloys in the Stainless family, where the bonds are more than sufficient structurally, as well as watertite. Though odds are, you'll only find them on custom boats. Or boats where a very knowledgable project manager/professional skipper oversaw their build.

The above's just a partial list of sins committed in rudder design & construction. Primarily on production boats. And the sad truth is, that on a lot of boats out there, rudders are one of those items which follow the " out of sight, out of mind" philosophy. And give the builders a place to save a little $.
Especially as they know that few people even begin to know what kinds of questions to ask about how rudders (and a LOT) of other parts of a boat are built.

For example, it'd be interesting to put up a survey on here, asking members/boat owners, if they KNEW for certain what their keelbolts were made of.
And I chose that for an example, as on a LOT of production boats, keelbolts are 304/306 Stainless. When for literally say $20 per boat, the builder could use different materials for the bolts which isn't subject to crevice corrosion. And would have a useable life long enough that the boat could be passed on to your great grandkids. With pretty much zero worries as to whether or not said bolts were in good shape as time went by.
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Old 25-10-2014, 15:36   #37
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Re: Rudder Failures

Can not read that far when all I asked is how many rudders you designed in order to claim MOST are under designed and built. Which of course is bs


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Old 25-10-2014, 15:52   #38
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Re: Rudder Failures

Quote:
Originally Posted by UNCIVILIZED View Post
Before I explain a few things on rudder design, construction, failures and the why. Here's an infobit sailorboy1. For a LARGE percentage of deep ocean races; now & in the past, carrying a viable emergency/backup rudder has been mandatory as dictated by various race governing bodies. Such rules came about as rudder, & steering failures are close to the #1 reason why boats had to withdraw from races part of the way through, & call for assistance... mid-ocean. The blades just spinning on the shafts like pinwheels.



I'm not certain as to whether you're asking for my background in engineering & design. Or why I made some of the statements that I did, regarding rudders.

Formal schooling - BS @ US Naval Academy, in addition to some graduate stuff. Including in Naval Architecture, & boat design & construction.
Informal - Beating the stuffing out of, & then repairing some of the top racing yachts in the world for a few decades. Even including the America's Cup, one in which I was hunted down, & asked to skipper a boat (with no job searching to participate in that race then, by me).

As an example of what "beating the stuffing out of" means. On one of the Maxi's I raced on, boats with sails which weighed in around a quarter ton each. We were doing a distance race, & several times a day (on bad days) the tail end of the vessel was pushed around enough by the waves for us to jibe, all standing, flying the storm kite & full main, in 30 - 40+ knots of breeze.

And primarily, it was just us, the core crew who did 95 percent of the care of the vessel. Not counting things like X-raying key rigging parts, or rebuilding engines.


As to rudders on production boats, & their design & construction. Let's start with the shaft. It may or may not conform to ABS rules (regarding size/strength), albeit said rules are not really sufficient when it comes to such things.
I say this, as for example (going off of memory), I believe that the Dashew's specify that the shafts on their sailing vessels to be built to 4x ABS rules at a minimum; although it may be 6-8x. No Joke.

Shafts, part II: When you install a thru hull in a boat, it's bedded into a flexible sealing compound. Both because hulls flex, and also because the various materials involved expand & contract at different rates.
- I can't say that I've seen much in the way of proper sealing of rudder shafts where they enter the blade, on your run of the mill boat. Such a seal doesn't need to be of the same type as on a thru hull. But there needs to be a SERIOUS connection there, and it must be waterproof. And durable enough to ABSOLUTELY maintain it's seal throughout, literally, tens, & hundreds of millions of cycles.
Few rudders meet this qualification, which is why it's not at all uncommon to see a small river pour out of a rudder when a hole's drilled near the bottom. Not an unusual test during a thorough survey.

Also, I've been sailing along on a vessel where all of a sudden we did a couple of quick 360's (with a kite & main up, Force 5). And when I look back, getting ready to ask the helmsman WTF in a rather direct & forceful manner. He too is looking back, & when I follow the sight line out to where he's looking, there's the bottom half of the rudder, bobbing up & down on the waves like a Styrofoam beer cooler lid.

Upon inspection of the rudder, there was massive water intrusion around the holes for the pintles & gudgeons. And a few phone calls, including to the builder, yielded the fact that such was a well known weak point in the boat/rudder (yes, including by the boat's builder).

The thing is, there was ZERO blocking, or extra reinforcement of the rudder in the vicinity of the bolt holes/pintles & gudgeons. Nor was there any sealant. Just some fiberglass skins, & a foam core.

On bigger boats, with a shaft, as alluded to above. Where water also penetrates these rudders. If one looks at how the structural framework of the rudder is spec'd out, & built, you'd KNOW common sense was dead.
There are production boats where the framework welded to the Stainless Steel shaft is... Cast Iron plating. And no, I'm not kidding.

Even on boats where the structural framework is Stainless Steel, the welds are often done with mild steel welding rod. And no special work is done to protect the welds after they're done. The thinking being, that the skins will keep out the water, so there's no need.
Also, often enough, the blades, or whatever is acting as framework in a rudder is simply welded in place. There are no slots machined through the shaft for a piece of plate, in addition to welding it. So all of the load is directly on the welds holding the framework to the shaft. And not at all in a direction where welds are at anywhere close to their strongest.

So, let's say, for argument's sake, that all of the metal used for the rudder's framework & shaft, is Stainless Steel. And we'll give the builder the benefit of the doubt that all of it's 316 or a similarly, more corrosion resistant alloy than 304/306.
- Keep in mind that putting Stainless Steel into water, or a moist environment with little oxygen is the definition of the recipe for crevice corrosion.
So that even when proper rod for welding Stainless is used, when you put it into this environment, you're asking for trouble. Ditto for the shaft & blade material.

If you take a look at Stainless hardware topsides. Most of it's polished almost to a jewelry finish. And many critical fittings are passivated on top of that. All of this being done, to prevent corrosion. Yet these Stainless fittings only get a good splashing on a semi regular basis. Not immersion 24/7 for life as is the case with rudder parts.

Some forms of stainless do work well for underwater applications, if chosen suitably for the task. Witness Aquamet/Nitronic 50 used for propeller shafts. Yes, there are better metals out there for the job, but it's passable.

Also there are ways of bonding fiberglass composites directly to some metals, including some alloys in the Stainless family, where the bonds are more than sufficient structurally, as well as watertite. Though odds are, you'll only find them on custom boats. Or boats where a very knowledgable project manager/professional skipper oversaw their build.

The above's just a partial list of sins committed in rudder design & construction. Primarily on production boats. And the sad truth is, that on a lot of boats out there, rudders are one of those items which follow the " out of sight, out of mind" philosophy. And give the builders a place to save a little $.
Especially as they know that few people even begin to know what kinds of questions to ask about how rudders (and a LOT) of other parts of a boat are built.

For example, it'd be interesting to put up a survey on here, asking members/boat owners, if they KNEW for certain what their keelbolts were made of.
And I chose that for an example, as on a LOT of production boats, keelbolts are 304/306 Stainless. When for literally say $20 per boat, the builder could use different materials for the bolts which isn't subject to crevice corrosion. And would have a useable life long enough that the boat could be passed on to your great grandkids. With pretty much zero worries as to whether or not said bolts were in good shape as time went by.

+111111
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Old 25-10-2014, 17:07   #39
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Re: Rudder Failures

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Old 25-10-2014, 17:27   #40
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Re: Rudder Failures

Quote:
Originally Posted by UNCIVILIZED View Post
Before I explain a few things on rudder design, construction, failures and the why. Here's an infobit sailorboy1. For a LARGE percentage of deep ocean races; now & in the past, carrying a viable emergency/backup rudder has been mandatory as dictated by various race governing bodies. Such rules came about as rudder, & steering failures are close to the #1 reason why boats had to withdraw from races part of the way through, & call for assistance... mid-ocean. The blades just spinning on the shafts like pinwheels.



I'm not certain as to whether you're asking for my background in engineering & design. Or why I made some of the statements that I did, regarding rudders

Formal schooling - BS @ US Naval Academy, in addition to some graduate stuff. Including in Naval Architecture, & boat design & construction.
Informal - Beating the stuffing out of, & then repairing some of the top racing yachts in the world for a few decades. Even including the America's Cup, one in which I was hunted down, & asked to skipper a boat (with no job searching to participate in that race then, by me).

As an example of what "beating the stuffing out of" means. On one of the Maxi's I raced on, boats with sails which weighed in around a quarter ton each. We were doing a distance race, & several times a day (on bad days) the tail end of the vessel was pushed around enough by the waves for us to jibe, all standing, flying the storm kite & full main, in 30 - 40+ knots of breeze.

And primarily, it was just us, the core crew who did 95 percent of the care of the vessel. Not counting things like X-raying key rigging parts, or rebuilding engines.


As to rudders on production boats, & their design & construction. Let's start with the shaft. It may or may not conform to ABS rules (regarding size/strength), albeit said rules are not really sufficient when it comes to such things.
I say this, as for example (going off of memory), I believe that the Dashew's specify that the shafts on their sailing vessels to be built to 4x ABS rules at a minimum; although it may be 6-8x. No Joke.

Shafts, part II: When you install a thru hull in a boat, it's bedded into a flexible sealing compound. Both because hulls flex, and also because the various materials involved expand & contract at different rates.
- I can't say that I've seen much in the way of proper sealing of rudder shafts where they enter the blade, on your run of the mill boat. Such a seal doesn't need to be of the same type as on a thru hull. But there needs to be a SERIOUS connection there, and it must be waterproof. And durable enough to ABSOLUTELY maintain it's seal throughout, literally, tens, & hundreds of millions of cycles.
Few rudders meet this qualification, which is why it's not at all uncommon to see a small river pour out of a rudder when a hole's drilled near the bottom. Not an unusual test during a thorough survey.

Also, I've been sailing along on a vessel where all of a sudden we did a couple of quick 360's (with a kite & main up, Force 5). And when I look back, getting ready to ask the helmsman WTF in a rather direct & forceful manner. He too is looking back, & when I follow the sight line out to where he's looking, there's the bottom half of the rudder, bobbing up & down on the waves like a Styrofoam beer cooler lid.

Upon inspection of the rudder, there was massive water intrusion around the holes for the pintles & gudgeons. And a few phone calls, including to the builder, yielded the fact that such was a well known weak point in the boat/rudder (yes, including by the boat's builder).

The thing is, there was ZERO blocking, or extra reinforcement of the rudder in the vicinity of the bolt holes/pintles & gudgeons. Nor was there any sealant. Just some fiberglass skins, & a foam core.

On bigger boats, with a shaft, as alluded to above. Where water also penetrates these rudders. If one looks at how the structural framework of the rudder is spec'd out, & built, you'd KNOW common sense was dead.
There are production boats where the framework welded to the Stainless Steel shaft is... Cast Iron plating. And no, I'm not kidding.

Even on boats where the structural framework is Stainless Steel, the welds are often done with mild steel welding rod. And no special work is done to protect the welds after they're done. The thinking being, that the skins will keep out the water, so there's no need.
Also, often enough, the blades, or whatever is acting as framework in a rudder is simply welded in place. There are no slots machined through the shaft for a piece of plate, in addition to welding it. So all of the load is directly on the welds holding the framework to the shaft. And not at all in a direction where welds are at anywhere close to their strongest.

So, let's say, for argument's sake, that all of the metal used for the rudder's framework & shaft, is Stainless Steel. And we'll give the builder the benefit of the doubt that all of it's 316 or a similarly, more corrosion resistant alloy than 304/306.
- Keep in mind that putting Stainless Steel into water, or a moist environment with little oxygen is the definition of the recipe for crevice corrosion.
So that even when proper rod for welding Stainless is used, when you put it into this environment, you're asking for trouble. Ditto for the shaft & blade material.

If you take a look at Stainless hardware topsides. Most of it's polished almost to a jewelry finish. And many critical fittings are passivated on top of that. All of this being done, to prevent corrosion. Yet these Stainless fittings only get a good splashing on a semi regular basis. Not immersion 24/7 for life as is the case with rudder parts.

Some forms of stainless do work well for underwater applications, if chosen suitably for the task. Witness Aquamet/Nitronic 50 used for propeller shafts. Yes, there are better metals out there for the job, but it's passable.

Also there are ways of bonding fiberglass composites directly to some metals, including some alloys in the Stainless family, where the bonds are more than sufficient structurally, as well as watertite. Though odds are, you'll only find them on custom boats. Or boats where a very knowledgable project manager/professional skipper oversaw their build.

The above's just a partial list of sins committed in rudder design & construction. Primarily on production boats. And the sad truth is, that on a lot of boats out there, rudders are one of those items which follow the " out of sight, out of mind" philosophy. And give the builders a place to save a little $.
Especially as they know that few people even begin to know what kinds of questions to ask about how rudders (and a LOT) of other parts of a boat are built.

For example, it'd be interesting to put up a survey on here, asking members/boat owners, if they KNEW for certain what their keelbolts were made of.
And I chose that for an example, as on a LOT of production boats, keelbolts are 304/306 Stainless. When for literally say $20 per boat, the builder could use different materials for the bolts which isn't subject to crevice corrosion. And would have a useable life long enough that the boat could be passed on to your great grandkids. With pretty much zero worries as to whether or not said bolts were in good shape as time went by.
If you are right and if that is that bad it is just a miracle that thousands of production boats cross the Atlantic each year, not to mention the ones that sail thousands of miles here and there, without a a big percentage of them losing the rudder. In fact the percentage to whom that happen is very small, if we consider the total number of production boats around.

I am not a great believer in miracles and I believe in statistics as a way to access reality..
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Old 25-10-2014, 17:44   #41
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Re: Rudder Failures

Rudder load can become a problem when the rudder is attached to the keel (full keel type design) or in the case of spade rudders, the rudder lacks balance. Balance is the 5-8% of the rudder's surface area that is to be ahead of the centerline of the rudder post. (NOTE: If the rudder is partially skegged, balance is calculated from the rudder area that is NOT behind the skeg. The inherent problem with full keel attached rudders, and fully skegged rudders: The lack of balance yields an ever increasing force of water against the upstream side of the rudder as it is moved side to side to steer the boat. As the boat travels faster, this force builds geometrically. Typically the load on such an old design is very very high when the boat is at maximum OR over max speed (1.5 root WL). We old sailors have experienced this load on boats with tillers. . .wheels have mechanical advantage; therefore the load is not felt and ignored.

Specific to the destruction of the ram: Rams should never be set to allow full through in either direction as this jambs the ram tight and stresses everything. Next, stainless steel stress hardens and will eventually just break - PING, that's it. There is should be some bending before this, so: Did you routinely check the ram for damage and wear? Is the A/P working too hard - can you move the wheel with 2 fingers on a spoke when you engage the A/P? If not, you've a problem with balance or friction; either way, the A/P takes the abuse.
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Old 25-10-2014, 17:54   #42
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Question Re: Rudder Failures

Quote:
Originally Posted by Polux View Post
If you are right and if that is that bad it is just a miracle that thousands of production boats cross the Atlantic each year, not to mention the ones that sail thousands of miles here and there, without a a big percentage of them losing the rudder. In fact the percentage to whom that happen is very small, if we consider the total number of production boats around.

I am not a great believer in miracles and I believe in statistics as a way to access reality..
Okay, for example's sake, let's take the ARC. And I don't know what the real numbers are, but let's say that 1% of them have serious trouble with their steering systems at some point between leaving Europe, & making landfall on the other side of the Atlantic.

To me, losing your steering system, is losing your steering system. So what do you think both the public outcry, & backlash to the auto industry would be like, if 1% of vehicles lost their steering systems in a cross country trip/every 3k miles?

And I'm posing the question so that it takes place in a world only partially like our own. In that, let's say that when the car's lost their steering, no one was injured.
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Old 25-10-2014, 18:22   #43
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Re: Rudder Failures

Talking about numbers i guess only a small portion of the cake report a rudder failure in the net..
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Old 25-10-2014, 18:35   #44
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Re: Rudder Failures

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Originally Posted by UNCIVILIZED View Post
Okay, for example's sake, let's take the ARC. And I don't know what the real numbers are, but let's say that 1% of them have serious trouble with their steering systems at some point between leaving Europe, & making landfall on the other side of the Atlantic.

To me, losing your steering system, is losing your steering system. So what do you think both the public outcry, & backlash to the auto industry would be like, if 1% of vehicles lost their steering systems in a cross country trip/every 3k miles?

And I'm posing the question so that it takes place in a world only partially like our own. In that, let's say that when the car's lost their steering, no one was injured.
Yes, let's take 2013 ARC as an example 360? participants and one rudder lost...but not on a production boat: It was on a steel custom Motiva 39. Regarding production boats 100% had no problems with the rudder.

Things seem better now that some years ago (with production boats ) on the years between 1998 and 2006, considering that about 1500 boats (probably more) made the ARC, there was 5 boats that lost the rudder. That gives a percentage of 0.0034. As I said from 2006 to 2013 not only the number of boats for edition has increased dramatically as the lost of a rudder become a rare event.

I think we can conclude that rudders are safer now in production boats that they were some years ago. Anyway given the lack of proper maintenance that most give to their rudders I am surprised at how solid they are: How many do you know that makes a complete check up, dismounting the rudder and changing the Teflon piece each 4 or 5 years? It is not an expensive operation, the price will go for less than 800USD on a 40 fter, nothing compared with the price you pay for having the boat on a marina.
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Old 25-10-2014, 18:57   #45
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Re: Rudder Failures

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Originally Posted by Polux View Post
Yes, let's take 2013 ARC as an example 360? participants and one rudder lost...but not on a production boat: It was on a steel custom Motiva 39. Regarding production boats 100% had no problems with the rudder.

Things seem better now that some years ago (with production boats ) on the years between 1998 and 2006, considering that about 1500 boats (probably more) made the ARC, there was 5 boats that lost the rudder. That gives a percentage of 0.0034. As I said from 2006 to 2013 not only the number of boats for edition has increased dramatically as the lost of a rudder become a rare event.

I think we can conclude that rudders are safer now in production boats that they were some years ago. Anyway given the lack of proper maintenance that most give to their rudders I am surprised at how solid they are: How many do you know that makes a complete check up, dismounting the rudder and changing the Teflon piece each 4 or 5 years? It is not an expensive operation, the price will go for less than 800USD on a 40 fter, nothing compared with the price you pay for having the boat on a marina.

Teflón is not used anymore my friend, Delrin is the right stuff this days, define strong Pólux because if you mean a hollow shaft surrounded by foam and covered with matt and maybe a decent layer of glass this is not strong in my book, with out mention the structure inside suporting the whole thing in some boats, where is that funny post about Foss Foam rudders and the builder claiming they need sun cream protection factor 15 to avoid problems, LMAO.....
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