Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-02-2013, 09:44   #31
Long Range Cruiser
 
MarkJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,828
Images: 25
Re: Do I need AIS?

Quote:
Originally Posted by conachair View Post
Are you sure it was ais they were looking at and not radar or visual?
Yep. the information on the phto shows it was 12th January 8pm, in the Florida Staites, so it would have been quite dark for a while.
In the top left corner you will see a range ring set at 10nm, so the alterations to course on each ship looks like they occured about 4nms distant, given that no one was panicking, the course changes would have been planned some minutes earlier, after the Captain was dragged kicking and screaming from the Bar.

My nav lights on the bow are new and pretty good LEDs CGF approved for 2nms and I am sure they would do far more (maybe 3?), but the aft LED would only just make the 2nms. So it wasnt visual.

I know you havent used AIS so it can be a little difficult to explain exactly how much better it is than radar - especially on a ships bridge in a busy place like that obviously was...
My AIS receives at about 40 nms 90% of all ships, and 100% at 30nms; 80% of Class B by 10nms and the rest a 5nms (Note that some Clas B setups are a bit crappy only transmitting 5 nms!). I think mine transmits at least 20 nms as someone said they were watching it from 18nms off when I was in Marsh Harbour and they were outside... so it had land in between.

The thing about AIS is it set off alarms on the ships bridge (and the yachts plotter too) when the closets point of approach comes within the shipping companies policy for CPA. The alarms, and indeed the signals themselves are recorded on the ships Black Box, and EVERY OTHER ships black box in the receiving area, so they cant pretend you were radar sea clutter etc Your AIS signal shows up and rings the bell!

AIS far outranges Radar. Iin one of the screenshots belwo see every ship in New Providence Chanel from Marsh Harbour. Radar cant do that!
Another shows ships Charleston South Caroliina to Brunswick, Georgia.

some people say navy ships dont use it... another shot shws they do.
and he either diverted or was setting up to fire torpedoes!

some say fishing boats done use AIS but many do... see the wierd stuff they were doing pair trawling

Finally with MSC Lisa see that even with the bells ringing, day time, visual sighting etc etc sail boats must realise that ships forget they have to give way to us! So we still need to be on the ball. I rang the guy on the VHF and he diverted...

AIS transponder is $499 at Westmarine... thats a great price.

I would never ever leave port without AIS again!

mark
Attached Thumbnails
Click image for larger version

Name:	abaco to nassau.JPG
Views:	133
Size:	145.8 KB
ID:	55097   Click image for larger version

Name:	ais georgia.JPG
Views:	117
Size:	49.5 KB
ID:	55098  

Click image for larger version

Name:	AIS Navy Ship.JPG
Views:	116
Size:	46.5 KB
ID:	55099   Click image for larger version

Name:	Capture.JPG
Views:	120
Size:	56.0 KB
ID:	55100  

Click image for larger version

Name:	fishing.JPG
Views:	121
Size:	57.2 KB
ID:	55101   Click image for larger version

Name:	MSC Lisa.JPG
Views:	119
Size:	56.7 KB
ID:	55102  

__________________

__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 18-02-2013, 09:50   #32
Long Range Cruiser
 
MarkJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,828
Images: 25
Re: Do I need AIS?

Oops, I missed putting the US warship in...

here it is.
Attached Thumbnails
Click image for larger version

Name:	navyshipais.JPG
Views:	132
Size:	63.5 KB
ID:	55103  
__________________

__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 18-02-2013, 10:00   #33
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,888
Images: 4
Re: Do I need AIS?

Only a few warships transmit, but they *all* receive and monitor.

MarkJ, your AIS ranges are perhaps a bit better than typical, but range can depend hugely on the atmospheric conditions. Some days I can receive ship's Class-A signals at 200 miles, but this is due to tropospheric propagation, often caused by a strong "marine layer". Other days they don't show up until they are 12 miles or closer. Again, due to the radio propagation conditions.

Fortunately, 12 miles gives us plenty of time to take action. Extreme ranges are interesting though. From my hilltop antenna I've received ships in excess of 2000 miles off.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 18-02-2013, 12:10   #34
Registered User

Join Date: Nov 2007
Location: Probably in an anchorage or a boatyard..
Boat: Ebbtide 33' steel cutter
Posts: 3,541
Re: Do I need AIS?

Quote:
Originally Posted by MarkJ View Post
I know you havent used AIS so.......
I have. Lots

I'm a huge fan!! Sorry, I wasn't having a dig, genuinely interested how it works on the big boys and if they use radar mostly , the monster says both, which is nice to know.
I have 2 receivers, a little nasa standalone and an engine onto opencpn, and agree , so useful don't leave port without one. My heart lies way offshore solo and they are an absolute godsend, & the number of lightships & marks transmitting seems to be gathering pace round the english channel now as well, virtual buoys may well become much more of a norm.
__________________
conachair is offline   Reply With Quote
Old 18-02-2013, 14:41   #35
Registered User
 
Kache Walk's Avatar

Join Date: Mar 2012
Location: Deale, MD
Boat: Hinterhoeller Nonesuch 30U
Posts: 69
Re: Do I need AIS?

I'm now convinced I should get a real, bonafide, AIS and not just an AIS receiver on the VHF. That means I can opt for a lower priced VHF and apply the left over cash to the AIS. I'll start my research on brand, etc.

Thank you. You've all been extremely helpful and patient with my learning curve.
__________________
Kache Walk is offline   Reply With Quote
Old 18-02-2013, 15:10   #36
Registered User
 
cfarrar's Avatar

Join Date: Apr 2008
Location: Brooklin, Maine U.S.A
Boat: Allures 44
Posts: 734
Images: 2
Re: Do I need AIS?

Great advice, here. Just realize that AIS is most useful for offshore traffic, shipping lanes, and busy ports. In my experience, when sailing the Maine coast in the fog, you'll need radar to see most traffic, including the ever-present lobster boats, which don't transmit AIS.
__________________
cfarrar is offline   Reply With Quote
Old 18-02-2013, 15:51   #37
Registered User
 
surfmachine's Avatar

Join Date: Jul 2009
Location: Cruising the West coast of Sumatra and the offshore islands, surfing!!
Boat: Feltz Skorpion mark 11A, Aluminium 39' sloop, constructed Hamburg. http://photobucket.com/eloise_01
Posts: 674
Images: 9
Send a message via Skype™ to surfmachine
Re: Do I need AIS?

The beauty of the SH matrix VHF radio and AIS receive is that you dont need a separate antenna for the AIS. Just replace the existing VHF with the SH matrix VHF and it all works! Go for a transponder and then you need an antenna splitter or another VHF antenna!
Keith.

In the Malaccan straits, not many of the 1300 foot boats doing 22 knots alter course to avoid me, a 40' aluminium sloop. I do all the manoeuvring!!!!
__________________
Keith, "But I was born very young and grew up knowing little of the world!" http://surfmachine-surfmachine.blogspot.com.au/
surfmachine is offline   Reply With Quote
Old 18-02-2013, 16:09   #38
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,389
Re: Do I need AIS?

Quote:
Originally Posted by Kache Walk View Post
I'm now convinced I should get a real, bonafide, AIS and not just an AIS receiver on the VHF. That means I can opt for a lower priced VHF and apply the left over cash to the AIS. I'll start my research on brand, etc.

Thank you. You've all been extremely helpful and patient with my learning curve.
Standard Horizon now makes VHFs with built in GPS, so you can save added wiring.

http://www.standardhorizon.com/index...3&isArchived=0

The REAL deal will be when they combine them all in ONE unit.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 18-02-2013, 16:51   #39
Registered User
 
Viking Sailor's Avatar

Join Date: Nov 2006
Location: San Francisco Bay
Boat: Fantasia 35 - s/v Feeling Good
Posts: 1,074
Re: Do I need AIS?

Quote:
Originally Posted by MarkJ View Post
Oops, I missed putting the US warship in...

here it is.
Hi Mark,

Sorry, but that is not a US warship. It is the British replenishment vessel Fort Rosalie. FORT ROSALIE - Vessel's Details and Current Position - 7341283 - 233063000

Best regards,

Paul

__________________
Viking Sailor is offline   Reply With Quote
Old 18-02-2013, 17:14   #40
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by surfmachine
The beauty of the SH matrix VHF radio and AIS receive is that you dont need a separate antenna for the AIS. Just replace the existing VHF with the SH matrix VHF and it all works! Go for a transponder and then you need an antenna splitter or another VHF antenna!
Keith.

In the Malaccan straits, not many of the 1300 foot boats doing 22 knots alter course to avoid me, a 40' aluminium sloop. I do all the manoeuvring!!!!
That's cause you don't have a transponder

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-02-2013, 17:17   #41
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by Kache Walk
I'm now convinced I should get a real, bonafide, AIS and not just an AIS receiver on the VHF. That means I can opt for a lower priced VHF and apply the left over cash to the AIS. I'll start my research on brand, etc.

Thank you. You've all been extremely helpful and patient with my learning curve.
Yes. The integrated receive only AIS isn't really a good deal. Get a cheap VHF and a AIS transponder. I notice the new Raymarine VHF 260 has an option for a full integrated AiS transponder. Standard and Garmin can't be far behind. I suspect later this year well see a whole slew of integrated AIS transponders into VHF.

Which if you think about it , is the logical place for it as it can share much of the modules of the VHF

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-02-2013, 17:35   #42
Registered User
 
Kache Walk's Avatar

Join Date: Mar 2012
Location: Deale, MD
Boat: Hinterhoeller Nonesuch 30U
Posts: 69
Re: Do I need AIS?

Quote:
Originally Posted by goboatingnow View Post
That's cause you don't have a transponder

Dave
LOL...sorry, that was funny.
__________________
Kache Walk is offline   Reply With Quote
Old 18-02-2013, 17:57   #43
Registered User
 
Greggegner's Avatar

Join Date: Nov 2010
Posts: 406
Quote:
Originally Posted by hpeer View Post

Just once makes it worthwhile.
I so agree...don't judge safety equipment by the number of times you use it....all it takes is once in the future.
__________________
Greggegner is offline   Reply With Quote
Old 18-02-2013, 19:31   #44
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,152
Re: Do I need AIS?

Quote:
Originally Posted by Viking Sailor View Post
Hi Mark,

Sorry, but that is not a US warship. It is the British replenishment vessel Fort Rosalie. FORT ROSALIE - Vessel's Details and Current Position - 7341283 - 233063000

Best regards,

Paul

In the link you provided if you look under Vessel's Wiki, it says Naval/Military Ship

In the US our military has supply ships that are either run by the Navy officers and enlisted or run by civilians. The civilian run ships ran by US merchant marine officers and crew are called Military Sealift Command ships and have a blue and gold stripe on their stack. MSC ships are considered military ships. MSC's name has changed to Sealift Logistics Command
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 18-02-2013, 19:37   #45
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,006
Send a message via Yahoo to roverhi
Re: Do I need AIS?

Have the West Marine Transponder AIS. Really neat to have on my sail to Hawaii. Leaving SF, was surrounded by ships till well past the Faralon Islands. They avoided me and I could tell their heading and speed to see if I needed to alter heading to stay out of their way. Never had to alter course as they all stayed clear.

On previous passages had seen only one ship and that was over the horizon. On this trip, picked up 4 ships on the AIS in the middle of nowhere. The most interesting was two ships on opposing course that bracketed me about 1/2 way to Hilo. Don't know if it was just because I had AIS or was sailing on a more populated route. In any case, both saw me on their screen and answered my call.
__________________

__________________
Peter O.
'Ae'a Pearson 35
roverhi is offline   Reply With Quote
Reply

Tags
ais

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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 -7. The time now is 00:31.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.