2018 Rolex Sydney Hobart Yacht Race: The Race Committee has lodged a protest against Wild Oats XI

[Maw]

Well you drew an ideal dipole response, the little loaded whips they put on the masts are not quite so directional, but you are dead right. The sats are sucking on the aether pretty hard to get the signals. There is some seriously fine engineering going on. (I did read about how they handled polarization a while back, but have forgotten what they did. It might even be possible it can be used to help untangle the slot overlaps.)

Polarisation scrambliing would fix it, but i dunno if the Class B units are that smart. 

 

[weightless]

Well you drew an ideal dipole response,

Yep. Worse, I stole that. Just the first image hit that was close. I think credit should go to: http://www.boat-project.com

 

[Crazy Cat]

I’m amazed you think AIS could have not been a tactical advantage. If you’ve ever done any one design offshore races you would have spent a lot of time conjecturing whether a competitor has better/worse breeze or current. You would have been keeping an eye on their bearing swith a compass, putting the binoculars on them to look at the pressure in their kite etc etc etc.

Imagine if you have their accurate boatspeed and heading on a screen but they don’t have yours? 

You said WOXI sailed an ‘average ‘ race despite them winning. Does that mean the other boats were below average?

Tricky

Fair point, however we are splitting hairs over the (almost) real time info from AIS vs the same info coming at 10 minute intervals from Yellowbrick. We are not looking at an alternative where there is zero information available. Yes instant is always better, but did it make a difference to how the other 100s sailed their race? Don’t know. 

No, my point is that WOXI did not sail the boat out of its skin as others have suggested. If they had done so they should have won by a greater margin in those conditions. The other three, especially the Indian being way out of its comfort zone, sailed great races. Stuck in the light for 3 hours on Thursday Comanche held their position against the others proving they have improved their performance down range. Blackjack probably saile least well of all, given it was mostly their forecast. 

 

[Essex]

I am a little surprised we apparently have so many who consider it OK to selecitvely follow the rules.

We could do worse than follow golf's lead where rules infractions are sometimes reported by viewers, and acted upon.

 

[Cal20sailor]

I am a little surprised we apparently have so many who consider it OK to selecitvely follow the rules.

We could do worse than follow golf's lead where rules infractions are sometimes reported by viewers, and acted upon.

Do you really think Trump has had a bad lie in the rough?  

But you're right, I've seen pro golfers take a penalty (many $$$$$$) for incidental infractions.  

 

[Cal20sailor]

Bummer. I thought that was all correct. What'd I fuck up?

Sorry, I'm just in a pissy mood.  Your picture was fine, but what is the gain on a cell phone and how does our government listen?  VHF on boats is a cakewalk.  

 

[Trickypig]

I am a little surprised we apparently have so many who consider it OK to selecitvely follow the rules.

We could do worse than follow golf's lead where rules infractions are sometimes reported by viewers, and acted upon.

In the interests of playing the game fairly any rules broken that give an unfair advantage is cheating.

To unintentionally or mistakenly miss something that has no bearing on the outcome  can be given a discretionary pass. Lets say WOXI forgot their v sheet or their first aid kit was missing a bandage. Would you happily disqualify them? If the answer is yes then you are preoccupied with right and wrong which is a sure sign of arrested development.

I think it is a major issue not because of non compliance but because of the tactical advantage 

 

[Maw]

A interesting point on the topic of not knowing if you have a failure of AIS TX from antenna or coax cabling.

The DSC function on your VHF receives at one of the AIS frequencies.

So, a simple DSC query of a boat,  and a successful response, would prove the antenna and coax were not a problem for AIS transmission for that boat.

Would it not?

 

[savoir]

Dumb question if I may:

How do I determine if my Class B transponder is CSTDMA or SOTDMA?

The only tech reference I can find to the satellite side is its a 50 channel IEC 61108-1 compliant device? 

Edit: I can see SOTDMA is referenced to the IEC standard, but no CSDTMA? 

If the unit has a 5w transmit power level it will be SOTDMA and 2w will be CSTDMA.

Eeeezzzeeee

 

[Maw]

If the unit has a 5w transmit power level it will be SOTDMA and 2w will be CSTDMA.

Eeeezzzeeee

Yep, I got you Savoir, I'd missed the VHF output was what I was looking for. Mine only shows the output power in dbm (33 ie: 2W), so I glossed over it.  

 

[Trickypig]

Tricky

Fair point, however we are splitting hairs over the (almost) real time info from AIS vs the same info coming at 10 minute intervals from Yellowbrick. We are not looking at an alternative where there is zero information available. Yes instant is always better, but did it make a difference to how the other 100s sailed their race? Don’t know. 

No, my point is that WOXI did not sail the boat out of its skin as others have suggested. If they had done so they should have won by a greater margin in those conditions. The other three, especially the Indian being way out of its comfort zone, sailed great races. Stuck in the light for 3 hours on Thursday Comanche held their position against the others proving they have improved their performance down range. Blackjack probably saile least well of all, given it was mostly their forecast. 

We can beg to differ on how well or badly each crew sailed then.

The website trackers are deliberately set up to be of less tactical advantage. There are other posts up thread pointing to the poor information that the yellowbrick  provides compared to AIS. 

 

[weightless]

Sorry, I'm just in a pissy mood.  Your picture was fine, but what is the gain on a cell phone and how does our government listen?  VHF on boats is a cakewalk.  

No worries.

Way beyond my ken and OT, but I didn't think the signal guys could intercept regular cell signals from space. Can they?

 

[Rail Meat]

In the interests of playing the game fairly any rules broken that give an unfair advantage is cheating.

To unintentionally or mistakenly miss something that has no bearing on the outcome  can be given a discretionary pass. Lets say WOXI forgot their v sheet or their first aid kit was missing a bandage. Would you happily disqualify them? If the answer is yes then you are preoccupied with right and wrong which is a sure sign of arrested development.

I think it is a major issue not because of non compliance but because of the tactical advantage 

I agree with that perspective.  

 

[LionessRacing]

I'm not sure "satellite based" means what you think it means.

Also most VHF antennas are less good at UP [sic] than out,

And polarization might be tricky.

It's kinda amazing to me that it works at all satisfactorily with the sats.

It’s line of sight. The trick is the satellite is NOT overhead but near the horizon. 

 

[Cal20sailor]

No worries.

Way beyond my ken and OT, but I didn't think the signal guys could intercept regular cell signals from space. Can they?

I can't comment but you may have seen my boat, it's called YES.  

 

[Cal20sailor]

It’s line of sight. The trick is the satellite is NOT overhead but near the horizon. 

FFS, it's an antenna gain pattern.  The lines do nothing but show the strength at that angle.  Plenty of stuff heading north.  

 

[LionessRacing]

FFS, it's an antenna gain pattern.  The lines do nothing but show the strength at that angle.  Plenty of stuff heading north.  

For any “gain” the “vertical” is necessarily “mathematically”  0. Arguably a boat undersail is never vertical and at 20 degrees heel there’s significant energy. 

 

[Cal20sailor]

For any “gain” the “vertical” is necessarily “mathematically”  0. Arguably a boat undersail is never vertical and at 20 degrees heel there’s significant energy. 

Accountant?  Sorry, still in a pissy mood but you don't get it.  

Think of a rock concert, can you hear them backstage?

 

[Francis Vaughan]

Think of a rock concert, can you hear them backstage?

Getting awfully geeky here.

For an ideal dipole the gain along the length of the dipole in indeed zero. Ideal means - in a vacuum, dipole has zero diameter, etc etc. The real world gain along the length of a dipole does still drop off significantly. 

Sound waves can also cancel out in exactly the same manner, but again, you need a dipole radiator. Most speakers are not dipoles. Certainly not PA systems. There do exist dipole speakers, and they have essentially no output side on. This is used to control room reflections and they are something of a darling of certain audiophiles. There is good theory behind the idea, and some significant downsides as well. The interested could check out Stanley Linkwitz's designs. He is a very respected EE, his ideas are not audiofoolery. (Unlike a lot else you might see put there.)

 

[Cal20sailor]

Getting awfully geeky here.

For an ideal dipole the gain along the length of the dipole in indeed zero. Ideal means - in a vacuum, dipole has zero diameter, etc etc. The real world gain along the length of a dipole does still drop off significantly. 

Sound waves can also cancel out in exactly the same manner, but again, you need a dipole radiator. Most speakers are not dipoles. Certainly not PA systems. There do exist dipole speakers, and they have essentially no output side on. This is used to control room reflections and they are something of a darling of certain audiophiles. There is good theory behind the idea, and some significant downsides as well. The interested could check out Stanley Linkwitz's designs. He is a very respected EE, his ideas are not audiofoolery. (Unlike a lot else you might see put there.)

I was talking to the masses and I am still in a pissy mood, I designed antennas from the ground up.  For me, it was always figuring out what we needed and finding out the closest thing the military had spent millions on.  Not that hard.  A boat being heard from space is not a challenge.  What's the gain on your EPIRB?