Arcona 460 sinks

[yotter]

Seems odd to break the stock a long way above the lower bearing, which is the most stressed area.
That suggests the quadrant must somehow have damaged the stock?

I don't think the buoyancy of the rudder will make much difference, the leverage of the blade against the single lower bearing would probably jam the stock in the bearing with even the slightest motion of the boat. Getting a simple dinghy rudder on its pintles afloat can be difficult enough.

I have agree. Is it not possible that the failure was at the lower rudder bearing, and the increased mobility of the stock caused stresses up at the quadrant. Still seems odd that there is not much sign of water ingress in the video, perhaps disproving my theory.

 

[Roberto]

Erm, are we idle talking forum-style about broken rudder shafts, or rather discussing about Calais, Lampedusa or Titanic-like episodes?

ow, the ocean can also be a cruel and horribly unforgiving place. When disaster strikes, everyone still alive leaves with dread and regret. I've seen boaters just through inattention get themselves into deadly trouble, seen drowned bodies being dragged up on the beach right in front of me by rescuers, and witnessed other near drownings. I have also had the privilege to lend a helping hand to someone who otherwise no doubt would have perished.

 

[RunAgroundHard]

It is obvious from the video that there is massive damage somewhere else that the where the quadrant was. The shaft is flopping from side to side, not rotating, and as reported, gouged a 15 cm hole in the boat. The failure at the quadrant is probably a red herring.

 

[Concerto]

Erm, are we idle talking forum-style about broken rudder shafts, or rather discussing about Calais, Lampedusa or Titanic-like episodes?

Funny, I thought this thread was about the sinking of an Arcona 460 in the Pacific, as per the thread title.

In my sailing experience I have never seen anyone who has drowned, but I have twice been involved rescues that would have resulted in certain death. The first was in February 1966 when we were sailing off the Isle of Sheppy and by chance came across an upturned dinghy with 5 fishermen in the water, 1 was unconcious. The second was in April 2015 when I heard a shout of help and looking round I saw a man clinging to a mooring buoy after he flipped his dinghy trying to board his yacht. Both events were close to shore, and accidents can happen anywhere.

The rudder breakage being discussed could have happened easily happened in sheltered waters as in the middle of the Pacific.

 

[Supertramp]

Well, luckily boats come in all shapes and sizes!

Personally, having worked for 35 years in high-tech engineering, I think I'm permanently banned from any Luddite community. From the rafts I used to build with logs and sticks as a kid, through all sorts of floating and not-so-floating contraptions, including a large number of kayaks, a multitude of cruising and racing sailboats up through IACC Americas Cup yachts, I have always enjoyed playing on and in water. All I can says is that a well-tuned high-performance sailboat brings me a joy that few other things can compare to.

Now, as we all know, the ocean can also be a cruel and horribly unforgiving place. When disaster strikes, everyone still alive leaves with dread and regret. I've seen boaters just through inattention get themselves into deadly trouble, seen drowned bodies being dragged up on the beach right in front of me by rescuers, and witnessed other near drownings. I have also had the privilege to lend a helping hand to someone who otherwise no doubt would have perished. We all have a responsibility to ourselves and all the people around us, to play responsibly, and use whatever information available to increase safety. Learning from IdaLina's unfortunate disaster is one way I think we can do that.

Thanks,

Anders

You are right and everyone makes their own choices of design and supplier, informed by knowledge, tradition and emotion etc.

It's easy to over react to an incident - plenty of boats with rudders like this are in hard use racing or cruising. I would want to know how many miles the boat had sailed, any grounding or tangling incidents and the result of Arcona fatigue testing on similar construction rudders.

Your rudder was fine last year and will no doubt continue to be this year. It may be a worry but you have identified precautions you can take and in time a reasoned solution will become clear. I for one would value your response once the facts and remedies are understood.

I speak from being on one of the OOD 34's that lost a rudder!

 

[Grace/Arcona-460]

It is obvious from the video that there is massive damage somewhere else that the where the quadrant was. The shaft is flopping from side to side, not rotating, and as reported, gouged a 15 cm hole in the boat. The failure at the quadrant is probably a red herring.

The text in Swedish of the last IdaLina instagram post says as follows: (I'm trying to translate as accurately as possible, not correcting things like punctuation or the change in tense mid sentence)

..."Our rudderstock broke and we fought for two hours to try to stabilize the rudderstock, in the end we had to unscrew the two quadrants for wire and autopilot and sink the rudder. Unfortunately, the lower rudder bearing was already detatched, and a 15 cm hole is filling the boat with water. We are trying to fill the hole with all equipment we had on board for this, an extra 220V bilge pump was working hard, but there was already 20 cm of water above the floors throughout the boat. The pumps we had were not sufficient, so we planned to leave the boat and packed everything we had time to get in waterproof bags"...

My assumption is that they tied the rudder down with lines under the hull, and that that is the reason the stock is not rotating. I assume it is a lot easier to stop rotation (by tying the rudder close to the hull) than to freeze the rudder in place entirely. I can't see how the broken rudderstock would be a red herring. It seems to me that it is the cause of the problem, and that the lower bearing has detatched from the hull and created a hole due to the movement of the broken rudderstock.

I'm itching to get to my boat, to see exactly how things are connected. In my mind's eye, I don't remember that my boat has two quadrants as the text mentions, but I'm not entirely sure how the autopilot is connected...

Thanks,

Anders

 

[RunAgroundHard]

Thanks for the translation and explanation.

 

[Grace/Arcona-460]

Erm, are we idle talking forum-style about broken rudder shafts, or rather discussing about Calais, Lampedusa or Titanic-like episodes?

I apologize if I brought this off topic. I am talking about people who went boating for pleasure. I had flashbacks for many years from their misfortune, but it is better now. In my mind the possibility of disaster is always linked with the enjoyment of activities on water, especially when pushing the envelope when it comes to boats and boat design.

Anders

 

[Grace/Arcona-460]

I speak from being on one of the OOD 34's that lost a rudder!

Wow, I can't even begin to imagine what that must have been like! Hope things stay that way...

I'll definitely report back here as things progress, and we learn more. Getting that bulkhead sealed watertight will definitely take a lot of worry off my chest. I will also inspect my rudderstock very carefully. Trying to line up someone to do a careful NDT examination of the rudderstock. Then we will see how to advance from there.

Thanks!

Anders

 

[Neeves]

316 Ultimate tensile strength 700 MPa
6082-T6 Ultimate tensile strength 330 MPa

316 Young's modulus 200 GPa
6082-T6 Young's modulus 69 GPa

You have your strength ratio the wrong way round.

We are both wrong.

Look at the yield of 316 stainless, around 200MPa

But my mistake, I was being lazy - I was thinking of the 7075 alloy, not the 6082. I was wrong and should have checked not relied on memory. You were right to correct me.

316 is a very strange material - its yield is very low - it just stretches and stretches, or yields. It may have a UTS of 700 MPa but yields at about 200 MPa - and then becomes useless (or I cannot think how it would remain useful)

If the application does demand stainless then the expensive duplex version might be more appropriate.

Jonathan

 

[AngusMcDoon]

.

 

[fredrussell]

Just thinking out loud here, but if one were to swim under the boat with, say, a bunched up duvet and force it up into the 15cm hole, would that slow the ingress of water enough for the bilge pump to keep up?

 

[vyv_cox]

Just thinking out loud here, but if one were to swim under the boat with, say, a bunched up duvet and force it up into the 15cm hole, would that slow the ingress of water enough for the bilge pump to keep up?

In the Crash Test Boat series in YM I think they did just that, although from inside, with a sleeping bag.

 

[Baggywrinkle]

Just thinking out loud here, but if one were to swim under the boat with, say, a bunched up duvet and force it up into the 15cm hole, would that slow the ingress of water enough for the bilge pump to keep up?

I unblocked a holding tank through-hull (a very unpleasant experience) under a Bavaria 37 last year by getting in the water approximately 1km off the shore in 30-50cm waves (in the Med, warm water and swimming trunks) ... I was totally exhausted very quickly, and the boat was all over the place even in such small waves, it was slamming me on the head and body and rolling like a pig. The slimy hull was impossible to get a grip of and I was constantly fighting my own buoyancy ... I had to stuff my fingers of my left hand in the other through-hulls to maintain position while working with my right hand - almost broke my fingers.

To attempt to take a duvet under the boat in the middle of the ocean would be suicide IMO - especially if the fiberglass under the hull was broken and exposed - diving gear would make it possible maybe, with ropes under the boat to maintian your position but after my experience I realised I completely underestimated how difficult it is to work under a moving boat - done it in harbours a few times without problems but when the boat starts moving it's a very different story.

With a hole that size though, you're screwed, and it's just a matter of time before the boat goes down. The crew survived, so I would chalk their actions up as a win regardless.

 

[Hacker]

You could attempt to fother it by attaching ropes to each corner of a sheet/duvet and pulling it under water to seal the opening. It saves you having to enter the water.

 

[geem]

...

You could attempt to fother it by attaching ropes to each corner of a sheet/duvet and pulling it under water to seal the opening. It saves you having to enter the water.

That sound great when sat in your armchair.
I went over the side earlier this year is 25kts and 2.5m seas to clear a line off the prop. We were tethered to some fishing gear. Seriously hard to do. The drift rate of the boat being about 1.5kts. Anything you do under water is impacted by the movement of the boat. Trying to position anything remotely would be impossible. Getting in the water with lines and stuff you can tangle with is a risk.
Not for faint hearted. I consider myself pretty fit. I run, kitesurf, wingfoil but the sheer physical effort to swim under the boat in 1.5kts was a shock

 

[dunedin]

...
That sound great when sat in your armchair.
I went over the side earlier this year is 25kts and 2.5m seas to clear a line off the prop. We were tethered to some fishing gear. Seriously hard to do. The drift rate of the boat being about 1.5kts. Anything you do under water is impacted by the movement of the boat. Trying to position anything remotely would be impossible. Getting in the water with lines and stuff you can tangle with is a risk.
Not for faint hearted. I consider myself pretty fit. I run, kitesurf, wingfoil but the sheer physical effort to swim under the boat in 1.5kts was a shock

I think that was why hacker suggested a possible technique worth trying that does NOT require entering the water.

 

[geem]

I think that was why hacker suggested a possible technique worth trying that does NOT require entering the water.

I understand that, but the point I was making is that nothing stays where you put it. The motion of the boat, the seastate and the current make it very hard to get anything to go where you want it. the risk of fouling on prop and rudder with any lines in the water is very high. To get a piece of duvet over a hole without actually seeing what you are doing by being in the water is very unlikely

 

[fredrussell]

In the Crash Test Boat series in YM I think they did just that, although from inside, with a sleeping bag.

I did think that from the inside would (obviously) be a lot easier, but perhaps the inflow of water was too great to do this. As others have said. armchair speculation and hindsight are wonderful things, and I assume the owners of the sinking boat either did try to stuff things down the hole, or perhaps didn’t have easy access to it.

 

[Hacker]

Fothering was (and possibly still is) a standard damage control practice in the RN. I’ve never done it in practice (either from my armchair or on a boat). I merely suggested it as a technique that didn’t require entry into the water.