Do I need AIS?

[MarkJ]

Originally Posted by conachair

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

[MarkJ]

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

here it is.

[Paul Elliott]

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.

[conachair]

Originally Posted by MarkJ

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.

[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.

[cfarrar]

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.

[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!!!!

[Stu Jackson]

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.

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.

[Viking Sailor]

Originally Posted by MarkJ

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

[goboatingnow]

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

[goboatingnow]

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

[Kache Walk]

Originally Posted by goboatingnow

That's cause you don't have a transponder

Dave

LOL...sorry, that was funny.

[Greggegner]

Originally Posted by hpeer

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.

[David M]

Originally Posted by Viking Sailor

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

[roverhi]

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.