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Old 13-05-2011, 13:40   #136
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Re: Floating Containers In The Ocean

At 6 knots, 36,000 feet per hour, you'd be traveling 600 feet per minute. About 100 yards/meters every 30 seconds.

So now assuming the forward looking sonar IS effective, and assuming it gives you a full 100 yard range...From the veyr moment it goes off, you've got 30 seconds to figure out what the problem, where the problem is, and swing to avoid it.

In theory that can be done. In practice? Will someone always be on or at the helm to respond that quickly? Or will this become yet another submarine movie cliche "I'm going to keep drilling this crew until we can crash dive in less than 30 seconds!"

Niel, I think that solution looks best on paper, but that most sailors just don't think it will work out on water.
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Old 13-05-2011, 13:40   #137
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Re: Floating Containers In The Ocean

Theoretically speaking about one minute! I do not know if the new generation sonars have a repeater that go off once a object is found but asuming it has, you still have one minute that you would'nt have had without a sonar, and i would say when that warning go off swerve sharp starboard side or port side, try start the motors to assist the turn and hang on. Should you hit a container while turning you just might shave the container which could veer you off in the direction you turned. On the other hand you might miss the container altogether by proactive reaction. No matter what, there is about 1 minute at 6 knots to do something that you don't have without a sonar.
In conclusion i am still of the opinion if a forward looking sonar can improve my chances with 1 percent at $1100 it's still be a bargain!
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Old 13-05-2011, 13:54   #138
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Re: Floating Containers In The Ocean

Oops i see my calculation is 30 seconds out! I just sank!!!!

I totally whole heartedly agree with you, theory is indeed patient! All of a sudden i now only have half a chance or half a percent and if i am on auto pilot having coffee at the galey which is down, i guess i am history! I do not know the odds of hitting a container but the a forward looking sonar is not limited to containers only and spotting containers might just be a bonus as there are certaily other uses and applications.
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Old 13-05-2011, 14:07   #139
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Re: Floating Containers In The Ocean

Some of the newer forward scanning navigational sonars claim 1200 - 1400 foot ranges, but I should imagine actual reliable range would depend much on size of the object in question and sea state. Practical ranges might be half that or less.

As to evasive action, if under sail, I would alter course and not waste time trying to get the engine started.

Like radar, forward scanning sonar is one more useful watchkeeping tool to augment the old eyeball.
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Old 13-05-2011, 14:11   #140
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Re: Floating Containers In The Ocean

We sit in the Gulf Sream, and our south shore gets a cosiderable amount of flotsam, ie, old hawser, commercial nets, floats, oil drums, etc. Never a container, to my knowledge. I know a number of ships have gone under, south of us, our press reports usually let us know.
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Old 13-05-2011, 14:44   #141
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Re: Floating Containers In The Ocean

If we were to list all of the things that can happen by listening to or reading of all of the things that have happened to people who use boats to travel over the water, it would be safe to say that there is an element of risk involved with our endeavor.
For we singlehandlers, items that must be monitored from the nav. station are usless because maintaining a proper watch must be our primary concern. Some items designed for safty of no use to use.
I had a terrible time explaining to a coastie that I didn't need a man overboard pole.
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Old 13-05-2011, 14:50   #142
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Re: Floating Containers In The Ocean

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Originally Posted by niel12 View Post
Containers and debri floating in the ocean is not a myth! Nobody should shrugg this off as "More likely to be hit by a car" it seem a bit reckless. I just hope that when you see a container you would be in time to avoid a colission. In other threads i mention the use of a forward looking sonar which to my mind improve ones chances. It's not expensive, $1100 for missing debri and containers! These sonars are quite efective over a distance of 100 meters, more than enough time to avoid a hit! These sonars are manufactured by most known brandames such as Garmin and Raymarine.
Floating containers at least if you hit one of them you have a platform to sit on.

Its the smaller things that are hard to see that I worry about they take your propeller/rudder off bend your drive shaft, kill your stern gland lucky if you don't start taking on water.

We were two boats travelling together the other boat in front and slightly to my port when my wife said "What's that"? pointing off the starboard bow.

We had already seen things floating objects plastic bottles the odd sandal and other rubbish, plastic bags and boxes, pieces of polystyrene. It was a floating railway sleeper partially submerged. We took evasive action and missed it but it was a close call.
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Old 13-05-2011, 14:52   #143
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Re: Floating Containers In The Ocean

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If we were to list all of the things that can happen by listening to or reading of all of the things that have happened to people who use boats to travel over the water, it would be safe to say that there is an element of risk involved with our endeavor.
For we singlehandlers, items that must be monitored from the nav. station are usless because maintaining a proper watch must be our primary concern. Some items designed for safty of no use to use.
I had a terrible time explaining to a coastie that I didn't need a man overboard pole.
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Old 13-05-2011, 15:03   #144
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Re: Floating Containers In The Ocean

Quote:
Originally Posted by John A View Post
...For we singlehandlers, items that must be monitored from the nav. station are usless because maintaining a proper watch must be our primary concern. Some items designed for safty of no use to use.
I had a terrible time explaining to a coastie that I didn't need a man overboard pole.
Ha! That's funny, John!

Thinking about it, all my sailing offshore has been essentially "single-handing" with respect to watch-standing, even though three other guys were onboard. The guy on watch was the only one on watch. Everyone else was asleep or otherwise occupied.

My first time out, I had some fleeting concerns about ramming a semi-submerged container, but the reality is it would be impossible to see or avoid at night, so I stopped worrying about it. In daylight, you might have a chance if the seas weren't too large. It's really hard to see something floating just at the surface until you're within a couple of boatlengths. A small whale crossed my bow just south of Guadeloupe. I saw it a boatlength away and threw the wheel over instantly. Missed him by about five feet. If I had had the autopilot on, I would have T-boned him.

To comment on the forward-looking sonar... I wonder how effective it is in offshore conditions where you're cooking along at close to hull speed in, say, 9-12' swells with crossing wind waves. I know that my standard depth sounder created false echos due to turbulence in conditions like that, frequently showing the depth to be 6', when it really was 3 miles. It might work fine on a large yacht with a deep hull, but I wonder how it would do on the boats the rest of us sail?
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Old 13-05-2011, 15:13   #145
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Re: Floating Containers In The Ocean

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... It was a floating railway sleeper partially submerged. We took evasive action and missed it but it was a close call.
I presume you are referring to what we call in the USA a "tie" which connects the rails and holds them to the roadbed, as opposed to a sleeping car.

Here the ties are faintly visible in the gravel roadbed in Sparta, Greece.


....
With all the hazards out there in addition to careless whales and mindless containers, no wonder boats never seem to leave their berths, only to await their sinking from the next tsunami or being burned up in a marina fire.
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Old 13-05-2011, 15:21   #146
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Re: Floating Containers In The Ocean

Thanks Astrid for that input, i was not aware of the newer sonar distances, it's encouraging. In terms of evasive action i agree whatever it takes however it takes just miss the darn container! In terms of starting the motors, well if they do start it might just help, especially in a short space of time as is a 100 meters

In terms of debri like a raiway sleeper or something similar the damage to one boat's under carriage could be disasterous. I particularly support the p-bracket support for the rudder and prop as the solid metal strip protect the rudder and the prop and in the event one does sail over a log of some form chances that it will damage your prop, propellar shaft and rudder seems much less as the log will just slide under over.
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Old 13-05-2011, 15:28   #147
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Re: Floating Containers In The Ocean

Hud i immagine in blue water conditions somewhat to what you described would more than likely also give you faulty readings, what however is to it's advantage is that the beam is horizontal and i am wondering just what reading you would get of a solid object in 6 to 12 foot waves?
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Old 13-05-2011, 15:35   #148
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Re: Floating Containers In The Ocean

Hi Mark, yea i suppose diffrent countries have difrent names but essentialy it's a hard type of wood of roughly 80cm wide X 50cm deep and about 2.5 metre long. The steel railway tracks are bolted onto them. They are called sleepers and in the states ties?
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Old 13-05-2011, 15:36   #149
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Re: Floating Containers In The Ocean

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In terms of debri like a raiway sleeper or something similar the damage to one boat's under carriage could be disasterous. I particularly support the p-bracket support for the rudder and prop as the solid metal strip protect the rudder and the prop and in the event one does sail over a log of some form chances that it will damage your prop, propellar shaft and rudder seems much less as the log will just slide under over.
Would this work (sans cradle)?

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Old 13-05-2011, 15:41   #150
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Re: Floating Containers In The Ocean

It looks about what i described i just cannot see where the rudder is connected. It's the area between the prop and the rudder that could be exposed.
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