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Old 16-11-2011, 12:29   #16
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Re: Yacht Sinks Off Western Australia Coast

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Originally Posted by AussieGeoff View Post
Steel is not invulnerable,
But it's getting there.

This one didn't hit a container, it was hit by a freighter. Didn't sink.






I haven't heard of any keels being lost, doesn't mean it hasn't happed though - any links? Mine's a long keel, no way that will be torn off.
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Old 16-11-2011, 13:17   #17
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Re: Yacht Sinks Off Western Australia Coast

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Would it actually work? I thought the forward range is quite short in deep water, so that at 5-6 knots you'd only have a few seconds warning?

The range of FLS actually improves as the water gets deeper. Generally it's around 4 times the water's depth. It's in shallow water where the range gets very short.

But as a warning device against collisions with containers it wouldn't work very well anyway, IMO. ( I have one) It's really designed to look at the bottom, not the surface, where waves would confuse the issue. At best, as you say, you might get a very short warning.

One instance where having a boat that physically CANNOT sink - ie. built of bouyant materials and carrying no ballast - would be a real advantage.
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Old 16-11-2011, 14:23   #18
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Re: Yacht Sinks Off Western Australia Coast

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Steel yachts can get their keels torn off in a close encounter with a shipping container, so the boat not only sinks, but often turns over and sinks inverted.

AussieGeoff
Owing two steel sailboats I'd like to hear more about how that happens.

The boats are constructed differently. The Brewer has the keel come up through the hull and is welded all around.

On the Pape the keel comes up to the hull, but not through. However it is still welded all around, inside and out.

I can't imagine anything separating the keel from the hull.
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Old 16-11-2011, 14:30   #19
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Re: Yacht Sinks Off Western Australia Coast

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Would it actually work? I thought the forward range is quite short in deep water, so that at 5-6 knots you'd only have a few seconds warning?
Concensus is that it doesn't work for containers.
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Old 16-11-2011, 14:33   #20
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Re: Yacht Sinks Off Western Australia Coast

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Steel is not invulnerable, ask the Captains of the Titanic and the Andrea Doria.

Perhaps it's time to consider a collision bulkhead and a forepeak packed with foam or something in the most likely point of impact.

That forward looking sonar is looking more and more attractive.

AussieGeoff
It amazes me that sailors will go to sea in vessels without watertight bulkheads or collision bulkheads.
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Old 16-11-2011, 15:40   #21
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Re: Yacht Sinks Off Western Australia Coast

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Steel yachts can get their keels torn off in a close encounter with a shipping container, so the boat not only sinks, but often turns over and sinks inverted....Ferro boats might do a little better, since the keel is integral...
Steelboat keels are about as integral as you can get...the whole dang thing is welded together to form a monolithic steel container. And when a steel container hits a steel container, both will float away with just with some dents and scratches. Ferro is your next best bet because it will crush and weep rather than hole so it will give a bit more time but steel is the only sleep easy material.
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Old 16-11-2011, 18:05   #22
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Re: Yacht Sinks Off Western Australia Coast

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Steel yachts can get their keels torn off in a close encounter with a shipping container, so the boat not only sinks, but often turns over and sinks inverted.
AussieGeoff, that is a very interesting statement. Do you have a link to a situation where that happened?
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Old 16-11-2011, 18:30   #23
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Re: Yacht Sinks Off Western Australia Coast

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Would it actually work? I thought the forward range is quite short in deep water, so that at 5-6 knots you'd only have a few seconds warning?
Several makers now build purpose designed forward looking sonar, for the purpose of detecting obstructions, not only containers, but ice and hidden rocks.

For instance:
Interphase: Ultrascan PC90

They advertise a maximum forward range of 1200 feet, roughly a fifth of a nautical mile. At six knots that would give you around 2 minutes warning. Even half that would be enough to avoid an object under most circumstances. Obviously more would be better, but it would give you time to react.

In the case of a container, it's like an iceberg, nearly all of it is below the surface, and in many cases, all of it, so it would be a very solid, and very large return. A minute or two of warning is better than none. You could certainly react to a radar return at that distance.

I'm not in the trade and haven't personally used this particular system, only seen demos and looked at the specs, so by all means make your own decision. I think there are other makers with this kind of gear as well, but we had an earlier Interphase system on our rescue boat and it did work quite well, we could get returns of a boat hull with only a couple of feet in the water, so I think a semisubmerged container would show up very well.

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Old 16-11-2011, 18:45   #24
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Re: Yacht Sinks Off Western Australia Coast

I'd have to look, probably. ISTR a steel hulled yacht lost it's keel to a whale, then turned over and sank. Naturally this only applies to a deep keeler and not only to steel hulls, wood and glass hulls with bolt on keels are equally vulnerable to an underwater collision with something substantial like a container or a whale I suppose.
I'll dig around and see if I can find the link.

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Old 16-11-2011, 19:14   #25
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Re: Yacht Sinks Off Western Australia Coast

I personally think it is all rather academic now, whether steel, GRP, wood etc. I believe it is safe to say, that the chances of hitting a container while making long passages at sea are steadily increasing (especially if you are now sailing between East Coast AUS and NZ after the Rena and Astrolabe Reef debacle).

Do your failure mode analysis, and prioritise what systems are in place.

What happens if I lose my rig in a blow? Can I survive, limp home? Most likely yes. What happens when the keel of my boat is torn off?

After a very quick look, it seems that this Interphase System is about 4 Boat Bucks + installation. I am not informed enough yet to know if this technology is mature enough, but if this (or a similar system) saves me from collision just once, it has paid for itself. Of course you still have to shell out the $$ in the first place, but ask yourself, do you really need those shiny new davits or that latest big screen chartplotter?

Just my 2c, YMMV

Tim
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Old 16-11-2011, 20:47   #26
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Re: Yacht Sinks Off Western Australia Coast

Um, pardon my ignorance, but what is a boat buck?

Concur with what you are saying, the risk seems to be on the increase.

Risk management requires an assessment of the risk in several ways, but broadly it comes down to two major factors, ie how likely is the event to occur? Highly unlikely, unlikely, somewhat likely, likely,almost certainly, or certain, combined with the consequences of the event. ie no damage or injuries, minor damage, no injuries, minor damage, minor injuries to one person, and so on, right up to Catastrophic, major loss or damage, multiple loss of life or life threatening injuries.

Given the increase in these events, I'd say it's probably moved from either highly unlikely to unlikely, or more probably from unlikely to somewhat likely.

So you have a somewhat likely event with possible catastrophic consequences. (Risk managers always take the pessimistic view, if they're wrong, no one is going to suffer for it that way).

On my risk-o-meter, it's now at the point where I need to do something about it.

So what are the options? Risk mitigation can take many forms, but prioritises protecting people first and property second.

What can be done to avoid the risk? Well, staying in the harbour probably works 100% but that's not really acceptable. Prevention or detection seems to be the answer if we aren't all to stay anchored somewhere or in shallow water.

Some of this would be best served from the container end. Redesign the blasted things so they AutoSINK.

Maybe some latches that release if the container is immersed, so the bottom falls out or the sides fall off and any buoyant contents can drift out, the steel shell would then sink quickly. I'd much rather plow through a school of cheap Chinese DVD players in their foam packing than the same with a steel shell around them. A bathymetric switch of some kind so it only happens when it's actually fully or partly submerged, with a delay if necessary, say, half an hour. Not that expensive, but on a global basis, difficult to implement, it would require legislation and that would need to be global, not easy to implement at all, possibly a long term goal.

Simplest solution of all: Ballast the things so they have negative buoyancy. Depending what's in them, some go down like a rock and aren't a problem. It's the ones whose content has sufficient positive buoyancy to offset the negative buoyancy of a steel framed box that are the problem. Getting container makers or shipping agents to make their containers guaranteed to sink will be somewhat difficult, as it means extra mass so less containers on the ship, but lead or whatever is cheap, so perhaps this is more viable than other 'high tech' methods mentioned.
Container sides and tops aren't terribly strong and not load bearing. The framework is the bit that does the damage when you hit it as it's heavy steel angle, this is the load bearing part of the container. The floors are heavier than the sides and roof, to carry the weight of the contents, but the frame is designed to support sevral containers piled on top, so it's substantial.

These below are expensive and on a global scale, difficult to implement at best, but I include them for completeness.

Put an automatic beacon on all of them, with a barymetric switch to activate it. Possibly a sonar beacon of some kind, might be a whole new product range there...
Otherwise AIS of some kind. Expensive? Yes. Complicated and difficult to implement? Hell yes, similar to the AutoSINK option.

Require ships to carry less containers and/or have them better secured. Probably worth doing, but again, global problem, and many govts may not be interested. But good in concept. If the darn things don't fall off, we can't run into them.

Prevention is always better than cure, so that should probably be something that could be lobbied for. Again, global problem, difficult to implement, but relatively cheap, so perhaps less 'consumer resistance' from shippers and shipping companies, shippers particularly may like the idea somewhat if it stops their container of rubber dog bones being a total loss.

Okay, non of that's worked and the darn things in the water and floating about six inches below the surface. Now what?

Avoiding known shipping lanes. May help, but containers drift a lot, some for years, the foam packing you have around a lot of electronics and other goods is very buoyant and they drift all over the place, so avoiding the shipping lanes may help you in the short time between the container falling off and it drifting out to sea or toward shore. Knowledge of likely drift patterns may be a help, if you know the shipping lane, you can think about going shoreward or seaward of it depending on tide and known currents.

A container is around seven or eight feet high, and if it's floating a foot or so below the surface, it's going to be aground in depths of less than about ten feet.

Unfortunately most cruisers would like more water than that under them, so going shallow is probably not an option for most, if you have something smaller that is happy in a few feet of water, if you stay inside the ten foot mark, you are probably safer from containers, but of course that does create other issues, like lee shores.

Perhaps we need some 'intelligence gathering' on where the darn things are sighted or hit. Securete messages about them are good, but perhaps we need some long term stats gathering on container 'hot spots', ie combinations of tide, current and weather contribute to where they end up, it may be possible to avoid at least some of it.

Ok, so we are avoiding the worst places, keeping a sharp lookout and hoping for the best. Hmmm. At night, the chances of see and avoid can be difficult with ships and boats you can see. Subsurface containers are very hard to spot during the day, at night, no chance realistically. Consider heaving to or anchoring overnight if you are in an area where there is some reason to think there might be lost containers drifting.

Then there are the high tech ways to see them.

If it's even a few inches above the surface, you may get a radar return inside a mile or so, watch for intermittent but apparently solid returns. If it's being tossed up out of the water by wave action, it will paint solidly until it drops back under.

Night vision. Well, better than nothing, but NV good enough to be useful still isn't as good as daylight and they are hard to see if submerged even in daylight. Useful generally, but not a huge help with this problem and even mediocre ones aren't cheap.

Back to the Forward Looking Sonar. Arguably the best of the 'tech' solutions to avoid them. Cost is the downside, but it can give you a minute or two of warning, day or night, less so in bad weather with the surface churned up, but you'll probably still get at least some warning.

Ok, that covers avoiding the collision. The last option in risk management is Personal Protective Equipment. If you can't mitigate or remove the risk sufficiently, then that's the last level of protection.
PPI for a yacht is difficult. Reinforce the bow, (think icebreaker) is difficult and expensive and depending what your boat is made of, may not be practical.
Maybe some sort of sacrificial 'bumper' the bulbous noses on cargo ships and the like are to reduce bow wave formation which reduces the amount of power necessary to push the hull through the water. I'm wondering if something like that, packed with impact absorbing material, might serve a dual purpose? Reduce your drag a little and act as a 'bumper bar', the shock would still be substantial and there is likely to be damage, but it might make the difference between something the pumps and you can handle and something that only gives you time to get out. At worst it might give you time enough for a safer evactuation.

A forward collision bulkhead, with the forepeak filled with foam or similar might be worth thinking about. I'm not sure what you could do to stop a bolt on keel being ripped off, but there are doubtless ways to strenghten it, not least of which is to make sure all the bolts are not fretting and consider installing more, there's a lot of weight down there on some boats.
I'm wondering if some bright spark could design something that might deflect an impact, push it to one side out of the way?

Ok, that's some ideas to kick around. I'm not an expert by any means, so I may be wildly optimistic about some of these notions, realistically, they are simply ideas to spur a discussion on what appears to be an increasing problem.

AussieGeoff
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Old 16-11-2011, 21:25   #27
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Re: Yacht Sinks Off Western Australia Coast

AussieGeoff,

A Boat Buck = $1000
A Boat Unit = $1000

Apparently a term invented to reduce the potential discussion from a Spouse who will almost always comment that such an investment could be better spent elsewhere....

As for the rest of your dissertation, slow day in Adelaide?

Actually, I thought we would just install the Interphase and be done with it

Seriously, some really good points, and I think this issue needs to be addressed more fully. I guess my viewpoint at the moment is that there is no way I can rely on others to make sure that there systems are working so as not to endanger me. I need to be proactive in reducing the risk to my crew and my vessel.

Need to leave for a while, so cannot comment more.

Cheers,

Tim
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Old 16-11-2011, 21:37   #28
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Re: Yacht Sinks Off Western Australia Coast

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Steelboat keels are about as integral as you can get...the whole dang thing is welded together to form a monolithic steel container.
Couldnt you use the same argument for a fiberglass keel?

Its coved and glassed to the rest of the hull making a monolithic fiberglass container
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Old 16-11-2011, 23:12   #29
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Re: Yacht Sinks Off Western Australia Coast

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Couldnt you use the same argument for a fiberglass keel? Its coved and glassed to the rest of the hull making a monolithic fiberglass container
Yes, but the materials are the issue then. A collision between a fibreglass container (the boat) and a steel container will result in only the steel one floating away. If the collision is between two steel containers, it'd be a dent and scratch 1-1 result.

Of course a steel boat with a canting keel is entirely a different matter - those keels are very vulnerable. But not too many cruisers are thus endowed.
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Old 16-11-2011, 23:13   #30
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Re: Yacht Sinks Off Western Australia Coast

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Actually, I thought we would just install the Interphase and be done with it


Tim
Please convince me that an Interphase will always pick up a container.

Have there been their any trials. Good spot off NZ at present for some trials. Would be good it it could be relied upon. Not sure ???

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