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Old 24-09-2013, 14:14   #76
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Originally Posted by Seaworthy Lass View Post

Generally by the time you are making evasive manoeuvres in regard to a large vessel when you are the stand on vessel, they are not in a position to be making a course correction significant enough to avoid you (they usually can't do much within a 2-3 nm of collision, depending on your closing speeds), so apart from unnerving their crew, this makes little difference .

I wouldn't say not effective, just progressively less effective. The closer the two headings, the less effective heading on a reciprocal course to the other vessel is as well (90 degree course change is best then).

True. I try never to be in such a situation though .

I think the safest correction is so dependent on the relative heading and speed of the two vessels, that it is very unsafe making any generalisations about the best strategy for evasive manoeuvres.
I think I agree with everything here. Valuable clarifications! This is a very good discussion.

I should have mentioned that my tack onto recip tactic is for a nearly perpendicular crossing and will not work for many other situations. Good catch, Seaworthy.
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Old 24-09-2013, 14:26   #77
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Originally Posted by skipmac View Post

So along this line, any specific recommendations as far as brand or model AIS transceiver? I see the Sitex online for about $550.

From initial research it appears that a basic unit will send output via NMEA to any MFD display that accepts NMEA input? Am I correct?
I have the Sitex and am very pleased with it. It has built in GPS which works below decks, it has a USB interface with good setup and control software (even built in SWR meter!), and it talks to my plotters over NMEA 2000 (many don't).

I think there are several others of similar functionality and price which are equally good.
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Old 24-09-2013, 14:30   #78
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Re: Big Ship Little Boat, who Gives way

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Originally Posted by nigel1 View Post
So many alternatives and so little time to type them all out
Of course you are correct, it's all down to circumstances and conditions (as mentioned a few times in the Colregs), and a main reason why arbitrary distances for taking action are not suggested.

Right now we're getting ready to leave Aberdeen and heading over to the Dutch side of the North Sea for a rigmove. I've advised our cadet he'll be going solo on the 8 to 12 watch, should be interesting, see how well theory is put into practise.
Which academy is your cadet from? As you probably remember, had Joe Hazelwood's Mate listened to the CMA female cadet, the Exxon Valdez wouldn't have grounded.
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Old 24-09-2013, 14:53   #79
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Re: Big Ship Little Boat, who Gives way

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Which academy is your cadet from? As you probably remember, had Joe Hazelwood's Mate listened to the CMA female cadet, the Exxon Valdez wouldn't have grounded.
Tend to call them Maritime Colleges over here, and the one in question here is Glasgow.
The other colleges my company use are South Shields and Southampton.

Did my time at Southampton and Liverpool
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Old 24-09-2013, 15:01   #80
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Re: Big Ship Little Boat, who Gives way

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Tend to call them Maritime Colleges over here, and the one in question here is Glasgow.
The other colleges my company use are South Shields and Southampton.

Did my time at Southampton and Liverpool
So you get both your Unlimited and a degree in Marine Transportation?
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Old 24-09-2013, 15:40   #81
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Re: Big Ship Little Boat, who Gives way

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So you get both your Unlimited and a degree in Marine Transportation?
The degree course over here is Marine Operations, most likely similar to Marine Transportation
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Old 24-09-2013, 16:02   #82
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Re: Big Ship Little Boat, who Gives way

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I have been thinking of getting a Standard Horizon 2100 with integrated AIS. I like the feature where you can call a ship on showing on the AIS via DSC. The only problem I have is they seem to have forgotten a possibly useful feature. The only option on the radio is to call the AIS target. I think it would also be useful to have the option of doing a position send to the AIS target so that your position showed up on the vessel's ECDIS display. Not quite as good as a full blown AIS transceiver, but possibly useful to a large vessel trying to avoid you. It would also not have the issue of timing and collisions(radio collisions, not ship) that can sometimes be a problem for class B in high traffic areas. In reading the manual you would have to manually enter the MMSI number of the ship in question, then transmit the position send rather than simply picking the ship off of the display. I was thinking of writing SH and making a feature request for their next generation, but would be interested in getting feedback from the forum on how useful such a feature would be.
I stand to be corrected , but I don't think IMO ECDIS displays DSC information in the first place.

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Old 24-09-2013, 16:06   #83
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Re: Big Ship Little Boat, who Gives way

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I'm disappointed how often sailboats and many motorboats have such tiny returns on radar. I recommend multiple radar reflectors or a metal boat.
One my biggest complaints is the number of improperly hanging octohedral reflectors.



Catch rain is much more effective. Last year in our medevac, the Captain of Navarino reported that he saw us visually before he picked us up on radar.

In future deliveries I will have the radar reflector in the catch rain position.
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Old 24-09-2013, 16:10   #84
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Re: Big Ship Little Boat, who Gives way

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I stand to be corrected , but I don't think IMO ECDIS displays DSC information in the first place.

dave
I think you are right Dave, there is no connection between ECDIS and DSC radio's (at least not on here)
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Old 24-09-2013, 16:10   #85
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Re: Big Ship Little Boat, who Gives way

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I was thinking that one of the problems in relatively high traffic situations is one vessel knowing that that the vessel they are talking to is the vessel they are looking at. Rather than having to give the vessel your position verbally, having them take the time to plot the position you just gave them and then make sure that they are looking in the right place takes a bit longer than simply hitting a position send button and having your current position pop up in their ECDIS display. With Class B AIS the position they have on their display may be quite old in a close quarters situation. The protocol for class B is much less dependable than class A when it comes to making sure you're being seen . With the position send option you could simply push that button and then follow it up with a verbal call.

You use the term transponder, rather than tranceiver. I'm getting a bit technical here, but a transponder is a device that responds to an interogation from a transmitter and sends a signal in return. A transceiver is simply a radio that is capable of both send and receive. I am a pilot and am quite familiar with tansponders. I am not aware of any transponder capability in the AIS protocol. My understanding is that all transmissions are in the blind and the receive simply reports on those transmissions. From your boat's point of view it receives and displays transmissions from other AIS transmitting vessels in range. It does not interogate those transmitters and get a fresh update. In turn your transmitter simply sends out your AIS information in the blind on a regular schedule, which in class B is not all that often and there is no collision detect in class b so you can't even be sure your transmission was not walked on and therfore not received by any vessels. Consequently your AIS position mght be quite old. If I am mistaken on my understanding of how AIS works please correct me. I have looked at Internet AIS tracking sites and have noted that many times class B positions are 20 minutes or more old in relatively crowded areas and when theypop up again they can be quite far from their last AIS position.

Lastly I need to replace my secondary radio and with installation a full transceiver would cost me more than a $1000 more than buying the integrated receiver and plugging it into an existing antenna system. $1000 may not mean much to you but it does to some of us.
actually both class A and B is both a transponder and a transceiver. in that shore stations can interrogate the unit and issue various commands as well.

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Old 24-09-2013, 16:12   #86
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I have been thinking of getting a Standard Horizon 2100 with integrated AIS. I like the feature where you can call a ship on showing on the AIS via DSC. The only problem I have is they seem to have forgotten a possibly useful feature. The only option on the radio is to call the AIS target. I think it would also be useful to have the option of doing a position send to the AIS target so that your position showed up on the vessel's ECDIS display. Not quite as good as a full blown AIS transceiver, but possibly useful to a large vessel trying to avoid you. It would also not have the issue of timing and collisions(radio collisions, not ship) that can sometimes be a problem for class B in high traffic areas. In reading the manual you would have to manually enter the MMSI number of the ship in question, then transmit the position send rather than simply picking the ship off of the display. I was thinking of writing SH and making a feature request for their next generation, but would be interested in getting feedback from the forum on how useful such a feature would be.
I have one and regret not going full AIS transponder. The transponder is on my wish list for 2014... Oh yeah if you have a Garmin chart plotter you may have issues. I have a thread going on NMEA 0183 issues related to the connection.



@Nigel--- thanks for starting this thread. It is VERY educational for us new to this level of boating
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Old 24-09-2013, 16:21   #87
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Re: Big Ship Little Boat, who Gives way

This is an excellent thread. I thank all who have posted. I have been doing some things correctly and now see the error of some other things. However in narrow/obstructed channels I will still wait in a safe/out of the way position till I am not sharing the channel with large commercial traffic. Might not work in Dodd Narrows though up in BC. Every one has to go thru together cause of tidal currents.
No one has opined regarding tugs and long tows, any thoughts?
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Old 24-09-2013, 18:37   #88
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Re: Big Ship Little Boat, who Gives way

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(...)

But the hazard, in my opinion, is taking action based on an unrealistic assessment of the situation. Probably unlikely for you, given your great experience. But many sailors simply can't comprehend the distance of the decision point, and the limitations of their own maneuverability, and make the wrong judgement.
Yes. There is no one simple theoretical answer to many complex situations on the water. You noticed I am always far from telling others how to do things much as I have some strong opinions on how I do them and why. I think I tend to over-dramaticize my posts at times. Something I am trying to correct in my less than effect-optimized nature. It is a process.

I am 100% with everyone who says there is no point in taking evasive action when there is no collision risk. I am also 50% with those who say stay on your course when you are supposed to stay on course. Do NOT mix up the guy on watch with your wrongly executed 'I am out of it' maneuvers. The remaining 50% is when I know that I can avoid any further convergence by simply tacking away and doing so very early on. Perhaps the key word is 'very early on'.

Now this whole AIS thing changed the game and I am still learning. Now we can see if the big ship is taking action and how early or late they tend to do so. We can also know their course and speed way before we can judge them by sight. And we can get this specific ship, by their name, on the VHF and they will find it extremely hard to dodge our call. This ads a layer of safety to whatever we are doing out there but as with all information, it too creates its own pitfalls and challenges. Still, I think it is a godbless. I just wish we can migrate to a transponder soonest.

The hazard you are talking about is real, serious and all skippers must bear this one in mind when making their decisions. I hope there are fewer accidents that result from 'too early, too much' action taken. I believe (mostly based on lecture of sailing magazines and sailing forums) there are more accidents resulting from 'too little, too late' action and from no action. Sure, I have no hard data and if such data existed I would love to read it.

I am very glad this thread developed this well. A day without learning something new is only half a day.

Cheers,
b.
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Old 24-09-2013, 18:41   #89
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Re: Big Ship Little Boat, who Gives way

Just so I can sort things out in this thread in my own mind, who here gets paid to go to sea, and in what rating?

Who stands watches as an officer?

Who is a deckhand?

Who read about it once in a newspaper in a foreign language in an airport between flights?
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Old 24-09-2013, 18:48   #90
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Re: Big Ship Little Boat, who Gives way

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Just so I can sort things out in this thread in my own mind, who here gets paid to go to sea, and in what rating?

Who stands watches as an officer?

Who is a deckhand?

Who read about it once in a newspaper in a foreign language in an airport between flights?
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