Another Bene with broken rudder bits

[TeddyDiver]

Originally Posted by letsgetsailing3

Ummm, what? You really can't have it both ways. Which is my point. You don't know what happened, or the history of that rudder.

Nothing to do with the rudder. I was talking about the indifference of tide in med compared to other phenomens affecting sea levels, and a bit warning aside to remember it everywhere when anchoring in shallow waters..
BR Teddy

[Polux]

Originally Posted by robert sailor

,,

I have my bias's and each of them has come through personal experience not what I read on forums. I sailed offshore 30 years ago in a C&C 36 and after a very rough sail 150 miles off the Wa/Or coast the top of the rudder post was loose in the bearing and had made the hole into an egg shape. I pulled the boat and had new bearings installed and the people at the yard also suggested that they beef up the support structure a bit as they considered it light duty. After sailing south and then over to Hawaii on the return trip to Canada the damn rudder was loose again and making noise each time we rolled. It really bothered me and I had a hell of a time sleeping worrying about it. I climbed into the back and over tightened the steering lines and it did quiet it down but I knew all I had done was put more load on the bottom bearing. I got us home but on return I had the whole area all redone again and I wrote off any future offshore cruising with a lightly built spade rudder. If they are built well and the support structures are built well they are just fine but in my experience in many of these entry level boats I don't see that as of course it cost money.

It seems to me that you should not avoid a lightly built spade rudder but a baldly designed one since what you describe seems to me clearly a problem of bad design. There are very light racing boats with very light spade rudders circumnavigating and doing on a 3 months more miles that you do in several years on worst sea conditions and except in what regards breakage due to collisions with heavy submerged objects they have very few problems.

Regarding trusting mainly your personal experience that seems not be a good method to learn a lot: If we consider the experiences of all that sail extensively offshore, the accumulated experience and knowledge will make yours minuscule.

In fact any experienced boat designer has much more experience regarding that than the one you can acquire over a lifetime of sailing: They designed hundreds of boats and have received the feedback of thousands of sailors through the boat builders that built their boats. They are learning for decades and applying that knowledge, that comes not only from their feedback but from the shared feedback of other boat designers, designing better, more efficient and more reliable rudder systems.

[Polux]

Originally Posted by Jon Eisberg

Well, it's one thing to have the bottom portion of a spade rudder designed/constructed to be 'sacrificial' in the event of a grounding or severe impact. ..
Again, it's one thing to have failures or breakages or bending of a rudder outside of the hull... But once structural components begin to fail inside the boat, that's a whole different ballgame... And again, if any builder actually intends for such an assembly to be 'sacrificial', they damn well better isolate that compartment from the rest of the boat with a watertight bulkhead... :-)
....

A rudder that bends can be an option, one that breaks at a controllable point another. On boats with carbon or composite rudder shafts bending is not an option.

Yes, a watertight bulkhead isolating the rudder area is a good safety option. Some boats have it (even production boats) others don't have it. Clearly the Beneteau on the movie did not have it but that has nothing to do with the advantage of having a sacrificial rudder conceived to break (or bend) without
damaging the hull.

[letsgetsailing3]

Originally Posted by TeddyDiver

Nothing to do with the rudder. I was talking about the indifference of tide in med compared to other phenomens affecting sea levels, and a bit warning aside to remember it everywhere when anchoring in shallow waters..
BR Teddy

Good point.

[Exile]

Can we back up a couple of steps and maybe avoid some further spinning in place?

First, Polux points out that designing a rudder that is sacrificial but won't sink a boat is a complex engineering job, often involving a watertight compartment to insure the boat doesn't sink. The ones I've read about are thus usually on higher end boats -- often "expedition"-type boats -- and the mfgs. make a point of advertising this as a worthwhile feature. Apparently this particular Bene was one of their lower end models -- wouldn't it be fairly easy to uncover whether the rudder was purposely designed this way? If it's not (which I suspect), then perhaps the discussion can be more productively focused on whether the light grounding we know about, or perhaps some other damage to the rudder we don't know about, should have been enough to damage the rudder post, etc.

(Ed. I missed where it looks like Polux already indicated this Bene did not have a purposely designed sacrificial rudder.)

Second, did I miss something with regard to the recent Hunter sinking at Avalon? I thought it was the holing in the bow section from contact with another boat that directly caused the water ingress & sinking. Other than knowing that the aft mooring pendant parted after the bow cleat got torn out, was there also a report of rudder damage on that boat?

[a64pilot]

Originally Posted by Polux

It seems that the one on the Hunter was too strong since it did not break in a way that would prevent boat flooding (damaged hull?)

The design of a sacrificial rudder is a complex one and the forces have to be carefully measured to design a system that would break in a clean and not harmful way before causing hull breakage and the boat to sunk. I don't have the data to tell you if it was well designed or not but those apparent fragile supports seem to be on the right place to be the first thing to fail, provoking the breakage of the rudder on that place that seems to me is the best place to limit damage to the hull integrity.

Maybe not, you can't design for everything, and just possibly that chain got around the rudder post or someting, one in a million, maybe.

Which takes us to the over built argument, yes it's heavy and more expensive to "overbuild" and except for the one in a million instance, it's wasted money.
Depends on just how un-likely an event you are willing to pay for, for protection. Money might well be better spent on other areas, like automatic fire extinguishing for instance, or a life raft, who knows?

Seems most of these accidents seem to be very un-likely and non-recurring that we read about, 10% of boats did not lose their keels last year, more like .001% or less?
During a design, you can't resolve to zero, there is an acceptable failure rate, I do not know what that is though.

In aviation the real big "gotcha" has become fatigue, you can design to be very strong indeed, but sometimes very strong can be prone to fatigue, so maybe in a few years strength has been reduced by half? A real problem is defining the "mission profile" how often and how large are the loads, and what is the design life?

All this is part of what leads to over building, if .5 inch is good, well then 1 inch ought to be better right?


Sent from my iPad using Cruisers Sailing Forum

[neilpride]

Originally Posted by Exile

Can we back up a couple of steps and maybe avoid some further spinning in place?

First, Polux points out that designing a rudder that is sacrificial but won't sink a boat is a complex engineering job, often involving a watertight compartment to insure the boat doesn't sink. The ones I've read about are thus usually on higher end boats -- often "expedition"-type boats -- and the mfgs. make a point of advertising this as a worthwhile feature. Apparently this particular Bene was one of their lower end models -- wouldn't it be fairly easy to uncover whether the rudder was purposely designed this way? If it's not (which I suspect), then perhaps the discussion can be more productively focused on whether the light grounding we know about, or perhaps some other damage to the rudder we don't know about, should have been enough to damage the rudder post, etc.

Second, did I miss something with regard to the recent Hunter sinking at Avalon? I thought it was the holing in the bow section from contact with another boat that directly caused the water ingress & sinking. Other than knowing that the aft mooring pendant parted after the bow cleat got torn out, was there also a report of rudder damage on that boat?

Is not rocket science, i can show you a rudder mold we have for a popular catamarán , is in the shop, talking about the lower portion of the rudder,
up there in the stock, post, bulkhead compartment things need to be equally really strong and well made, under any circumstance a rudder post can be loose for a soft grounding or normal load and even in the rare event of a hard grounding or collision the goal is to try to keep the boat watertight, the true is and is a fact for some production boats in the way to save weight and cost , they dont pay to much attention to this vital part of the boat, rudders and keels...... get under the rudder post cave in a 90`
First 45 and later in a Brand new Oceanis, you can see the diference , is there ....

Is kinda lame how some brands solve the rudder post , bulkhead configuration, even a novice can do the whole thing better....

[Polux]

Originally Posted by Exile

..
First, Polux points out that designing a rudder that is sacrificial but won't sink a boat is a complex engineering job, often involving a watertight compartment to insure the boat doesn't sink. ...

No I did not said that. I said that a water tight bulkhead isolating the rudder area from the rest of the boat was a safety factor but what I said was that had nothing to do with a sacrificial rudder:

"Yes, a watertight bulkhead isolating the rudder area is a good safety option. Some boats have it ... others don't have it. ... but that has nothing to do with the advantage of having a sacrificial rudder conceived to break (or bend) without damaging the hull."

[Exile]

Originally Posted by Polux

Your last remark is particularly rude. I did not understood why his thread was closed. Besides being controversial never saw any special rudeness there, only different opinions and that it is about that a forum is about.

Regarding is signature line, never saw nothing regarding nobody in particular and if that was the case it certainly would not be allowed.

Never saw also any remarks that could be considered offensives and many have been rude to me. He had a particular style but the fact is that he was contributing actively to this forum and his threads were and are hugely popular. I will not comment moderation decisions more than you do, but I will have to say that I will miss him and it seems I am not the only one.

Polux -- with respect, the reason you didn't see the type of rude posts or offensive signature lines that presumably ran Smack afoul of forum rules is because they were deleted by the mods, and probably very quickly given his previous history and openly stated agenda & intentions. I'm no more privy to the inner workings of CF than anyone else, but I can tell you that Smack & I both had an exchange of posts deleted by the mods very quickly, and in my case it was because I responded by suggesting he was an internet troll (bad form, I know, and apologized). But again, all of my comments above came from Smack's own public blog & some of his public comments on SN, many of which openly boast about his various bans on this & several other sailing forums.

I would have to agree that Smack started thread topics that became very popular, but only part of that was because the topics themselves were interesting. Much of it was on account of people responding to the divisiveness he purposely generated. This is not just my personal observation & opinion, but also according to Smack's own publicly stated intentions.

Each forum gets to set its own rules, and CF's seem to try and emphasize civility. In other words, it's more about "how you do it" than just "what you do" according to their's. I, for one, was much more swayed by all of the accounts you took the time to dig up about people doing bluewater adventures in production boats than anything Smack ever presented. Who knows, maybe his motivation was simply to generate internet traffic over to his blog where he has items listed for sale and a donation button, or maybe it was simple self-aggrandizement, but whatever it was it repeatedly ran afoul of CF rules, and I suspect he was repeatedly warned before he was permanently banned.

[Exile]

Originally Posted by Polux

No I did not said that. I said that a water tight bulkhead isolating the rudder area from the rest of the boat was a safety factor but what I said was that had nothing to do with a sacrificial rudder:

"Yes, a watertight bulkhead isolating the rudder area is a good safety option. Some boats have it ... others don't have it. ... but that has nothing to do with the advantage of having a sacrificial rudder conceived to break (or bend) without damaging the hull."

Sorry Polux. Certainly didn't mean to misquote you. I got the impression that a watertight bulkhead goes along with a sacrificial rudder, but apparently that is not correct. But to be clear, my understanding is that neither of these two features exist on the Bene in question here? Correct me if I'm wrong please.

[robert sailor]

Originally Posted by Polux

It seems to me that you should not avoid a lightly built spade rudder but a baldly designed one since what you describe seems to me clearly a problem of bad design. There are very light racing boats with very light spade rudders circumnavigating and doing on a 3 months more miles that you do in several years on worst sea conditions and except in what regards breakage due to collisions with heavy submerged objects they have very few problems.

Regarding trusting mainly your personal experience that seems not be a good method to learn a lot: If we consider the experiences of all that sail extensively offshore, the accumulated experience and knowledge will make yours minuscule.

In fact any experienced boat designer has much more experience regarding that than the one you can acquire over a lifetime of sailing: They designed hundreds of boats and have received the feedback of thousands of sailors through the boat builders that built their boats. They are learning for decades and applying that knowledge, that comes not only from their feedback but from the shared feedback of other boat designers, designing better, more efficient and more reliable rudder systems.

When I use the term "lightly" built I am meaning not strong! I know that things can be built light and very strong but I don't think this was the case.

[Polux]

Originally Posted by Exile

Sorry Polux. Certainly didn't mean to misquote you. I got the impression that a watertight bulkhead goes along with a sacrificial rudder, but apparently that is not correct. But to be clear, my understanding is that neither of these two features exist on the Bene in question here? Correct me if I'm wrong please.

A watertight bulkhead certainly not, we can see that on the video. Regarding a rudder that bend or break before causing problems to hull integrity that is a characteristic all good NAs try to manage on the boat design and the Cyclades 43 was designed by one of the best (Berret & Racoupeau design).

[Jim Cate]

Originally Posted by Polux

A watertight bulkhead certainly not, we can see that on the video. Regarding a rudder that bend or break before causing problems to hull integrity that is a characteristic all good NAs try to manage on the boat design and the Cyclades 43 was designed by one of the best (Berret & Racoupeau design).

I'm getting confused here! Seems to me that in the case of Blue Pearl, the internal structure's failure lead directly to hull integrity failure, and thus the boat sank. To me, this indicates that the NA failed to provide what you (Pollux) are saying was there. If the rudder or the shaft had failed, the hull damage shown would not have occurred and the boat might have survived.

Having the "fuse" failure point internal to the hull was fatal in this case.

Jim

[sailorboy1]

Hard to use a boat that had already experienced enough earlier damage to require a rudder replacement to make a point about the design elements of rudders. In my opinion.

[robert sailor]

Beneteau Cyclades 43 Review: Moorings Charter Boat - Waves « Jordan Yacht Brokerage

Polux read this report on the boat. This is a very knowledgeable guy and he suggests that this boat, the 43 we are talking about is not a candidate for a safe offshore cruiser. The Cyclades 50 is built to similar scantlings and even though it is a larger boat my hunch is that it would get a similar review. I got exactly the same feedback from a well known surveyor in Europe. It is also interesting that it failed in the same place as the 50.