Reply
 
Thread Tools Search this Thread
 
Old 01 September 2011, 15:51   #1
RIBnet supporter
 
C2 RIBS's Avatar
 
Country: UK - England
Town: Hants
Boat name: Gemineye
Make: Ribeye S850 charter
Length: 8m +
Engine: 300hp
MMSI: 235097445
Join Date: Sep 2007
Posts: 3,029
AIS issue

The latest RYA info shows
"Growing concern that ships are able to filter out AIS Class B transmissions
However, more recently, the Royal Institute of Navigation and indeed the RYA has noted growing concern among the leisure boating community that despite the revised radar performance standard, ships are able to ‘filter out’ AIS Class B transmissions from small craft. Such a facility is open to misuse and ultimately makes the fitting of anything other than a receiver a fairly pointless and expensive exercise."

If this is the case then clearly any of us opting for AIS could be filtered out of a ships radar view even though we would still see them or is this RYA info misleading?
__________________
Ian
Rib charter and Rib hire with www.c2ribs.co.uk
C2 RIBS is offline   Reply With Quote
Old 01 September 2011, 16:08   #2
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
I had to read the article a couple of times to try and understand it. In one paragraph it stated that no manufacturer produces a unit that can filter out the signals and then in the next breath says that units can be set to filter.

I would have thought that there would be risk of negligence aimed at any captain who decides to filter out the signal if it results in a collision. I also don't see where the logic of clutter comes in either. Surely the time when there is 'clutter' is the busiest and most risky for collison and they would want all info available on other vessels tracks that they can get.
Erin is offline   Reply With Quote
Old 01 September 2011, 18:38   #3
SPR
Trade member
 
SPR's Avatar
 
Country: UK - Scotland
Town: Central Belt of Scotland
Boat name: Puddleduck III
Make: Bombard
Length: 5m +
Engine: 50 HP
Join Date: Mar 2009
Posts: 2,066
AIS can be displayed in Radar or a separate screen.

The RYA article stated AIS B can not be filter at the native level, but could be filtered at the RADAR screen where most of the traffic is displayed.

The 15 min transmission delay on AIS B, means you could well be on a vessel before your position has been updated...on the ships screen.

So in theory you better not being on the system, and the radar will filter out "unreliable" / "Historic" information from radar.

Looks like the Echomax Active X S is the way to go, and AIS receiver unless your are using the AIS B to track your higher fleet or training boats etc, where 15mins delay is not an issue

15mins at 30 knots you can be a fair distance !
__________________
SPRmarine / SPRtraining
RYA Training Courses & Safety Equipment Sales
SPR is offline   Reply With Quote
Old 01 September 2011, 19:20   #4
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,924
RIBase
There's a 15min delay on AIS B? Do you mean websites that reuse that data?
__________________
willk is offline   Reply With Quote
Old 01 September 2011, 19:33   #5
SPR
Trade member
 
SPR's Avatar
 
Country: UK - Scotland
Town: Central Belt of Scotland
Boat name: Puddleduck III
Make: Bombard
Length: 5m +
Engine: 50 HP
Join Date: Mar 2009
Posts: 2,066
Quote:
Originally Posted by willk
There's a 15min delay on AIS B? Do you mean websites that reuse that data?
Doh! slaps head in homer simpson style!

why did I think AIS B was 15 mins delay (-prob because I been selling SPOT 2 messengers today, that up dates there tracking every 15 mins when in tracking mode!)

AIS B is every 30 seconds By default , at 2 watt
AIS A is every few seconds and at 12 watt

S.

PS. RYA Article AIS transmissions from small craft | Current Issues | Cruising | RYA

Automatic Identification System - Wikipedia, the free encyclopedia
__________________
SPRmarine / SPRtraining
RYA Training Courses & Safety Equipment Sales
SPR is offline   Reply With Quote
Old 02 September 2011, 03:13   #6
Member
 
Channel Ribs's Avatar
 
Country: UK - Channel Islands
Town: Alderney
Length: no boat
Join Date: Sep 2006
Posts: 3,047
The RYA article concludes that AIS B is not a single cure for all, they recommend that it be used as part of a balanced diet.
__________________
Channel Ribs is offline   Reply With Quote
Old 02 September 2011, 04:36   #7
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by Erin View Post
I had to read the article a couple of times to try and understand it. In one paragraph it stated that no manufacturer produces a unit that can filter out the signals and then in the next breath says that units can be set to filter.

I would have thought that there would be risk of negligence aimed at any captain who decides to filter out the signal if it results in a collision. I also don't see where the logic of clutter comes in either. Surely the time when there is 'clutter' is the busiest and most risky for collison and they would want all info available on other vessels tracks that they can get.
Yes I can't understand why a ship would want to turn off this unless there was so much "clutter" that it was obscuring other relevant info (like the other big ship ahead). That situation can really only be a problem in places like the solent (where its likely that a large vessel is constrained to the channel and "class b" boats would have to give way anyway). I'm not sure what the RYA is getting its knickers in a knot about: even without the ability to hide class B boats there is no guarantee that the bridge crew will identify and respond to any impending collision anyway. AIS transponder may be useful tool but its not human proof at either end, so best to assume you may not have been seen until you see evidence to the contrary. The same applies to Echomax/Seame - it will only help if everything works as intended and then the human beings in the system react correctly - 99% of the time they will but to rely on it is a bit of a gamble.
__________________
Poly is offline   Reply With Quote
Old 02 September 2011, 15:37   #8
Member
 
Anchorhandler's Avatar
 
Country: France
Town: Huisnes sur Mer
Boat name: Raufoss
Make: Avon
Length: 4m +
Engine: Mercury 50
Join Date: Sep 2010
Posts: 789
Quote:
Originally Posted by Polwart View Post
Yes I can't understand why a ship would want to turn off this unless there was so much "clutter" that it was obscuring other relevant info (like the other big ship ahead). That situation can really only be a problem in places like the solent (where its likely that a large vessel is constrained to the channel and "class b" boats would have to give way anyway). I'm not sure what the RYA is getting its knickers in a knot about: even without the ability to hide class B boats there is no guarantee that the bridge crew will identify and respond to any impending collision anyway. AIS transponder may be useful tool but its not human proof at either end, so best to assume you may not have been seen until you see evidence to the contrary. The same applies to Echomax/Seame - it will only help if everything works as intended and then the human beings in the system react correctly - 99% of the time they will but to rely on it is a bit of a gamble.

Could'nt have said it better myself...
There are time when i look at our 22" monitor in our office and all i can see is red triangles clogging up the solent. (i will take a screenshot tomorow and post the picture)

There are times when class B AIS is invaluable for leisure boaters but do you really need to have it switch on when your daylight sailing in the Solent or other busy coastal cruising area?...i dont believe so.

Offshore, when near or crossing shipping lanes, night time navigation, fog...yes, switch that baby on... (imagine if the Ouzo could have had AIS fited?) . but a certain degree of restraint should be excersised before that 'on' button is pressed.
I wish yachties would treat their AIR transponders as " a big very bright all-round nav light", fantastic in the right conditions (again, night time, fog etc....) but not in daylight when they are surrounded by hundreds of other yachties all showing the same dazzling all-round light....it just creates confusion for those trying to distinguish one 'light' from another.

Simon
__________________
C'est pas l'homme qui prend la mer, c'est la mer qui prend l'homme....
Anchorhandler is offline   Reply With Quote
Old 02 September 2011, 15:48   #9
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Simon, what fraction of solent pleasure craft are transmitting? Can you imagine 15yrs time when most might be, as cost falls?
__________________
Poly is offline   Reply With Quote
Old 02 September 2011, 17:05   #10
Member
 
Anchorhandler's Avatar
 
Country: France
Town: Huisnes sur Mer
Boat name: Raufoss
Make: Avon
Length: 4m +
Engine: Mercury 50
Join Date: Sep 2010
Posts: 789
Quote:
Originally Posted by Polwart View Post
Simon, what fraction of solent pleasure craft are transmitting? Can you imagine 15yrs time when most might be, as cost falls?
Yep, scary stuff....it definately has the potential of being a victim of its own success.

I would estimate that in the last three years alone the number of pleasure boats transmitting in and around the IOW and Solent must have nearly trippled.

It used to be quite a novel experience spotting a 'leisure' AIS target amongst all the commercial stuff, especially when the said target had an unusual or comical name (a few weeks ago a yacht in Cowes was broadcasting 'Sheik Ya-Bouti' which made us giggle). But nowadays its only really during the week when the ratio of 'commercial to leisure' swings in our favour. On the weekends, its very much a different story!

For us its just a serious inconvenience but for the likes of VTS it can be a real problem.

Its actually quite comical sometimes to 'see' what is in effect virtual 'motorways' on our screen, made up of AIS transmitting yachties all following each other through defined navigational channels (exiting the Hamble river is a prime example)

Simon
__________________

__________________
C'est pas l'homme qui prend la mer, c'est la mer qui prend l'homme....
Anchorhandler is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 17:11.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.