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Old 11-07-2013, 20:27   #811
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Re: Freighters vs. Sailboats

Several things come to mind. First is: You can always learn something.

I did not know that there is a mathematical way to discern the 'cone of death' regarding the arccosign of the vessels speed. (not that I would use it, or depend on it)

Regarding the ability to 'point at the stern', Lodesman you are correct, that for vessels meeting 'end on, or nearly end on' pointing at the stern is not the answer.

BUT, for just about any other instance it works.

My issue is that the newbie reading this could infer from your post: Any time a collision will occur the we will be "dead ahead" Or "fine on the bow".

Both those are incorrect. The most important thing is the variability of a sailing vessels speed. Reaching, as the wind freshens, (or drops) the speed can jump from 5 to 9 pretty quickly. To assume that for the 'next 18 minutes/ (as in the described scenario) the sailboats speed will remain consant is not wise, not practical, and most importantly not probable.

In this example, (which i did 5 times, with mechanical pencil, and actual triangles) the widest I could find to approach and collide was 16 degrees. (Throw out the extra 1.5!) In this case, if at 4 miles the SV altered course to the Stern of the freighter, the CPA would IMMEDIATELY open, the ship would 'see' the cpa open dramatically on the RADAR screen (if plotting) and there would be no reason to have to change underwear.

I try to keep the big issues to the KISS principle. Not everyone agrees. Some like to 'stand tall' and get it 'their way'. Others, try to go along to get along.

It seems that close quarters situations happen because there are some who just don't know. If you can't figure out how to 'follow the rules', then you have to exercise caution to stay alive. Just having a big checkbook doesn't cut it.

The funny thing is, as much as it is discussed about 'wanting to get where you're going', or standing on, this whole encounter shown will be OVER and done with in just over 15 minutes! how much would you have to 'go out of your way' to stay alive? OR, more pertinantly, show others how to stay alive?
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Old 11-07-2013, 20:34   #812
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Re: Freighters vs. Sailboats

Quote:
In this case, if at 4 miles the SV altered course to the Stern of the freighter, the CPA would IMMEDIATELY open, the ship would 'see' the cpa open dramatically on the RADAR screen (if plotting) and there would be no reason to have to change underwear.
Also, if the SV were plotting, OR simply observing, the ship would radically change bearing by the altering of course.

The bad thing about altering is, (from a small vessels view) you don't know IF the ship has started a turn to avoid you. They turn relatively slowly which makes analysis more difficult.

And THAT would be an excellent topic for another discussion, "Left handed Navigation" and why it's dangerous. BUT, in this case it would be nice to just stay alive.
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Old 11-07-2013, 20:36   #813
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Re: Freighters vs. Sailboats

Rakuflames:

Have you not heard of the two SVs in a race off the california coast earlier this winter missing? One they only found chunks of the boat. the other they have NEVER located.

The topic is alive and well in Davy Jones Locker.
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Old 11-07-2013, 20:56   #814
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Re: Freighters vs. Sailboats

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Originally Posted by Rakuflames View Post

If I were going to be sailing in this area at night I would most definitely look into AIS (don't know enough to say I would buy it) ...

but will shrimp fleets show up on it? Of course, they're lit up like Christmas trees, but there's always fog ...
I've just passed dozens over the month of June in the ICW, Neuse River and PAmlico Sound. 15 just yesterday. I don't think one of them popped up on AIS. most were smaller boats, but several bigger ones too. I had to hail one as "southbound shrimp boat" at the Morehead City Bridge, as we were going to pass at/near the bridge and I had a knot and a half of current with me. None really monitor 13 either. I hailed a bunch of them to see how the catch was and eventually had to use 16.

Not all the tugs pop up on the AIS in the Beaufort/Pamlico area either. Maybe in FL the shrimp boats have AIS...

I was sailing a less traveled section of the Pamlico Sound a year ago and came across a shrimp boat. I was under full canvas and made considerable effort to get out of his way, call on radio, etc. After having to make at least three course corrections I finally just stood on and got back on course. He was trawling in a serpentine pattern which makes it difficult to figure out whats going on.
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Old 11-07-2013, 20:59   #815
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Re: Freighters vs. Sailboats

Regarding AIS, Half the idea of AIS to to be able to get info about other vessels.

The other half is to BE SEEN. If you are going to spend the couple hundred dollars for the 'receive only' PLEASE spend the extra couple hundred and get the full class A. I would appreciate it!
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Old 11-07-2013, 21:19   #816
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Re: Freighters vs. Sailboats

[QUOTE=cappy208;1283045]Several things come to mind. First is: You can always learn something.

I did not know that there is a mathematical way to discern the 'cone of death' regarding the arccosign of the vessels speed. (not that I would use it, or depend on it)

Regarding the ability to 'point at the stern', Lodesman you are correct, that for vessels meeting 'end on, or nearly end on' pointing at the stern is not the answer.

BUT, for just about any other instance it works.

My issue is that the newbie reading this could infer from your post: Any time a collision will occur the we will be "dead ahead" Or "fine on the bow"... QUOTE]


Cappy, you don't have to worry. Beginners stopped reading long ago!!!
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Old 11-07-2013, 21:25   #817
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Re: Freighters vs. Sailboats

Quote:
Originally Posted by cappy208 View Post
Rakuflames:

Have you not heard of the two SVs in a race off the california coast earlier this winter missing? One they only found chunks of the boat. the other they have NEVER located.

The topic is alive and well in Davy Jones Locker.

That's a big assumption without more evidence. The two boats could have collided. We don't know they hit freighters -- what -- both of them? Neither of them, presumably experienced sailors, could miss a freighter? They have fully trained crew, probably one person doing just or mainly navigation, and they still hit a freighter?

There was no investigation? that would have turned up any freighters in the vicinity, and surely the boats would have at least left a mark.

I did see a video of a racing SV hitting a freighter of the English coast. that was remarkable ...

I said a long time ago that this was who I thought needed to do things like calculations based on hand-held bearings -- racers who don't want to lose even ten extra seconds avoiding a big ship. No one else has any reason (or excuse) to cut it close.

But if those boats are gone, the crews are gone, and I can't believe no investigation was done. An investigation would reveal any freighters in the area and it would be easy to compare the two routes, etc. In the Isla Mujeres race, the boats have chips that plot their course every step of the way.

Simple matter of whether and when the vectors intersect. Then examine the freighters. I don't believe that under those circumstances, a freighter could get away with sinking two sailboats with all hands aboard and yet not reporting it.

Didn't the SVs have EPIRBS?

Got a source for this? So many questions! I COULD believe this story but I don't have nearly enough information to believe it yet.
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Old 11-07-2013, 21:27   #818
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Re: Freighters vs. Sailboats

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Originally Posted by cheoah View Post
I've just passed dozens over the month of June in the ICW, Neuse River and PAmlico Sound. 15 just yesterday. I don't think one of them popped up on AIS. most were smaller boats, but several bigger ones too. I had to hail one as "southbound shrimp boat" at the Morehead City Bridge, as we were going to pass at/near the bridge and I had a knot and a half of current with me. None really monitor 13 either. I hailed a bunch of them to see how the catch was and eventually had to use 16.

Not all the tugs pop up on the AIS in the Beaufort/Pamlico area either. Maybe in FL the shrimp boats have AIS...

I was sailing a less traveled section of the Pamlico Sound a year ago and came across a shrimp boat. I was under full canvas and made considerable effort to get out of his way, call on radio, etc. After having to make at least three course corrections I finally just stood on and got back on course. He was trawling in a serpentine pattern which makes it difficult to figure out whats going on.

Where I am many of the shrimp boat captains see themselves as the center of the universe and ignore (or even harass) other vessels. By "harass," i mean going out of its way through an anchorage to roll the live-aboards around. Apparently they think it's funny and it never occurs to them that a small child or animal might be seriously injured, thrown around in the cabin.
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Old 11-07-2013, 21:29   #819
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Re: Freighters vs. Sailboats

Quote:
Originally Posted by cappy208 View Post
Regarding AIS, Half the idea of AIS to to be able to get info about other vessels.

The other half is to BE SEEN. If you are going to spend the couple hundred dollars for the 'receive only' PLEASE spend the extra couple hundred and get the full class A. I would appreciate it!

Well, yeah, that would really be the point of it. I know that those big boats actually may not be able to see me visually. I get it.
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Old 11-07-2013, 22:29   #820
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Re: Freighters vs. Sailboats

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......
Unless you are in the intracoastal...or a sailing/power regatta (marine parade)...the prudent skipper alters course far enough in advance NO RULES apply...
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Originally Posted by goboatingnow View Post
Therein lies the kernel of good yachtsmanship. And in the open ocean it's sound advice
This is precisely why we give freighter operators nightmares!

If you are scanning the horizon every 10 minutes (and there is a lot to be said for stepping this up to 5 min and improving technique) you may first be spotting a freighter at only 5nm. Otherwise it is 5-10 nm with good visibility.

The freighter is possibly commencing a turn (not apparent to us yet as he is slow to make changes) at exactly this stage. If we react instantly thinking we are in open water and should just stay clear, it is violating ColRegs and our action may put us back on collision course.

Anyway, at 5-10 nm when we first spot the freighter, we are only determining that there may be a risk of collision, there is no certainty as there is a few degree error in the estimate, even with the radar on. We don't want to be making huge course corrections unnecessarily and the one one thing we mustn't do is make small changes to our course at this stage - it is VERY confusing for the freighter.

This is a fine art in determining when to turn away so that you are not making a big change in course totally unnecessarily (here in the Med there are often one or two freighters visible and I don't want to be constantly doing this) AND so you are not just avoiding hitting but giving yourself a safe margin, AND you are not changing course at a time the freighter is expecting you to hold it (and that regulations say you should).
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Old 11-07-2013, 23:23   #821
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Re: Freighters vs. Sailboats

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Originally Posted by Lodesman View Post
If your sailboat is going 4 or 5 kts and the freighter is going better than 20 kts, and if a risk of collision exists, you will be fine on his bow - this is a mathematical certainty.
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My issue is that the newbie reading this could infer from your post: Any time a collision will occur the we will be "dead ahead" Or "fine on the bow".

Both those are incorrect.
Lodesman's example was where there was a large difference in speed between the two vessels (at least 4-5 times greater for the freighter).

The most common speed of all freighters I have encountered in open water is about 16-18 knots. Our speed is a little more variable , but 5-6 knots is very common for us in the Med (we often sail in light air). I would say the most common situation is where the speed of the freighter is around three times that of our yacht.

If the freighter's speed is three times greater (or more), the yacht's angle on the freighter's bow does actually have to be narrow (less than 20 degrees) for them to collide - I don't mean pass very close, I mean COLLIDE.

Cappy, could you please find one example for me where the freighter's speed is 3 times (or more) greater than that of the yacht where they will actually collide if the angle of the yacht from the freighter's bow is greater than 20 degrees?

This of course does not allow for a safety margin, not does it work if the speed of the freighter is less than 3 times that of the yacht, but it is a very useful bit of knowledge, as we do know our speed and it is generally fairly stable in open water .
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Old 11-07-2013, 23:28   #822
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Re: Freighters vs. Sailboats

Sailed sailing boats make constant course corrections due to lifts and knocks either by hand steer or setting the Autopilot to follow the wind angle, a sailing boat will always confuse if it's being plotted by the bridge of a large vessel.

EBL or taking an hand bearing compass angle allows plotting also line of sight constant angle observation from your helm seat, sighting through a stay/winch top whatever should be your constant task.

AIS used as a tool gives you the call sign of the vessel in question enabling direct communication.

No AIS then the call is 'vessel at position' etc.

Communication is a fantastic tool if radios are not an option due to language barriers/reception/ignoring then a TACK away shows complete unconfused intent with emphasis on 'away'.

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Old 11-07-2013, 23:51   #823
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Re: Freighters vs. Sailboats

Something to be aware of AIS shows an icon on a plotter's screen, the Icon is not accurate in it's relative position to you on the screen, you must go to AIS Info to get accurate position and bearing of the 'target'

The visual icon on the screen should only be used as an indication that there's a vessel equipped with AIS in the vicinity.

Conjointly using Radar overlay is helpful.

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Old 12-07-2013, 01:47   #824
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Re: Freighters vs. Sailboats

Quote:
Originally Posted by cappy208 View Post
Regarding AIS, Half the idea of AIS to to be able to get info about other vessels.

The other half is to BE SEEN. If you are going to spend the couple hundred dollars for the 'receive only' PLEASE spend the extra couple hundred and get the full class A. I would appreciate it!
I think you mean a transponder, instead of just a receiver. Either a Class-A or a Class-B transponder will broadcast your position.

It's interesting that cappy208 (who helms a tug if I recall correctly) is asking for more pleasure craft to carry a transponder. We have been told by some that transponders on the little guys just cause confusion! For what it's worth, my sailboat has a Class-B transponder, and I'm glad we have it.
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Old 12-07-2013, 01:49   #825
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Re: Freighters vs. Sailboats

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An easier and more appropriate method is use a hand bearing compass. Constant bearing = collision.
Actually "Constant bearing" has two possibilities - collision or no collision.


I have never seen this written before, but a constant bearing will only result in a collision for converging tracks.

If your tracks are even slightly divergent (and this may not be obvious at a distance) and you are getting a constant bearing, no collision will occur.

This is of particular significance if you have made a significant change in course and still find the other vessel is still on a constant bearing. It need not be because they made a course correction at the same time. It may just be that your tracks are diverging now. You will not collide then, despite the constant bearing.

Now, there is something for all of you to think about .
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