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Negrini, I don't know if you actually understood or not...

What I meant, is here, we use true wind to measure the merda de boi that goes on in the BFS thread....get it?

over there, the true wind is allways up by 50%...
 

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Jim,

the ST60 is NOT to be used to tell you where, as in which magnetic direction, the wind is coming from..it's used to tell you, in relatiion to your bow, where is the true/apparent wind and how strong they are...

It's a sail realted instrument, not a navigation instrument.
What the Portagee is attempting to differentiate here is the difference between true wind direction and relative wind direction. (Neither of which has anything to do with apparent wind.) Without a compass interfaced, all readings for true wind (and relative wind) will be referenced to the angle off the bow, the relative angle or the relative wind direction. The vessel's heading must then be applied to the relative wind angle to derive true wind direction. To do so automatically you'd need some type of heading input such as a flux-gate compass or GPS.

All of this gets back around to my frustration with "those people" who, one, seem bound and determined that every instrument on board will be from their company and, two, drop the ball repeatedly when it comes to interfacing logically interfaced components.
 

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Discussion Starter · #23 ·
It is nothing more than a sailing aid...
Which would be my purpose. My main reason for wanting to know true wind speed is to know if I'm getting the most I can out of her for given conditions. Sure, we can go back to Sailflow, after the fact, but, especially sailing on Lake St. Stupid, as we do, what the buoys report and what was reality are not necessarily the same thing. An exchange between xort and I a couple months back, where we'd both been near, but on opposite sides of the same buoy, at the same time, and experienced completely different wind conditions was a perfect example. Secondly: True wind bearing would be handy, during races, for determining favoured tack: No?

Jim
 

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Guys :

What is the difference between relative wind and apparent wind?
Are they not the same?... I mean, wind relative to the boat being the same as wind apparent to the boat?


The difference between true and relative I can grasp, but between relative and apparent ? Surely they are the same?
 

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Jim,

the bridge works only if you have the SOW available in a different format (NMEA for instance), translating into/from Seatalk. If you like the ST60 Speed/Log, then you'll be ok, as it will put such sentence into Seatalk net. Should work plug-and-play.
 

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Discussion Starter · #27 ·
Jim,

the bridge works only if you have the SOW available in a different format (NMEA for instance), translating into/from Seatalk.
Not true, according to the link Brak provided: gadgetPool.de Forums-viewtopic-SeaTalk-NNMEA-Bridge : True Wind direction SOG/STW (from the thread you referenced earlier in this thread). That device optionally rewrites SOG sentences to STW sentences, fooling the ST60 wind instrument into thinking it's getting what it wants.

It's unforutunate Raymarine's marketing and engineering departments are so moribund as to make a 3rd-party "hobbiest" device like this necessary for something so trivial. Raymarine is a division of Raytheon. The latter is a big supplier of high-tech military hardware to the the U.S. military. Things that make you go "Hmmm..."

That device isn't iimportant to me, being as, as I noted earlier, current is almost never much of an issue where we currently sail. For us: The ST60 speed log's output would do the trick, and we already have that device. (Not that we're inclined to spend over US$1000 on the wind instrument, anyway. I started this thread out of simple curiousity.)

Jim
 

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oooops ! you're right. I did same using my laptop for a while. But following term strictly, this is not a bridge, as shouldn't modify the content, just the envelope. Anyway, I didn't try this product but looks wise since they realised right a way the use of STW is wrong. If you have a chance and try it, let us know ....
 

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BTW, as per Beneteau "give away" I have a ST speed/log too. But this is a real mess to plug the paddle. I don't consider myself skilled disabled, but I find it somehow difficult to plug it. Is there any tip or different procedure people use to cope with that ?
 

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Discussion Starter · #30 ·
BTW, as per Beneteau "give away" I have a ST speed/log too. But this is a real mess to plug the paddle. I don't consider myself skilled disabled, but I find it somehow difficult to plug it. Is there any tip or different procedure people use to cope with that ?
If you're talking about removing the transducer for cleaning and putting it back in: Yes. Tho no procedure is going to completely eliminate some water getting in, the man who surveyed our boat said the mistake that most people make is trying to remove one and plug in the other all in one go. Instead, he said, remove one, quickly slap your hand over the hole, grab the other and quickly plug it in.

I'm still working on being quick :p

Because our boat spent so much time in her slip this last season, the paddle-wheel on the transducer was reluctant to move freely. On the second cleaning I finally got it good and clean and we never had any further trouble. I'm going to stash a small rosin brush on-board for that purpose. A small, relatively stiff-bristled paintbrush would work, too.

Jim
 

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Nice tip, I'll give it a try .... I found it interesting as you leave yours in, then un-plug for cleaning. I leave mine off, then plug when need info ... barnacles here would block the paddle within a week or so .... thanks.
 

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Rocky,
True wind can be expressed two ways, either by true direction/bearing or relative direction/bearing. The true wind might be from 045 degrees (NE) and it might be then something completely different depending on the boat's heading relative to the wind for relative wind. Relative wind can be referred to either from 0 degrees to 180 degrees, port or starboard. Or it can be referenced 0 to 360 degrees clockwise from the bow. The former is more common.

You'll have noticed I left apparent wind out of the description as it's a completely different animal.
 

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Sail....

I thought apparent wind and relative wind were the same thing. The boat would "see" the wind direction relative to the boat, and so what it "sees" is "apparently" happening. Maybe not.

I am not keen on those dinky toy instruments anyway. On a long crossing, they tend to get seawater-damp and drop out on you. For now, I have GPS (16 years old, and still running), water speed, water depth, and next season a masthead wind speed indicator (apparent!!) is planned. That should be enough. The British(?) outfit NASA seem to make a good one, and it's not too expensive.

Most of the time when you are watching wind speed is when you are getting blasted by a gale. Relative and apparent arguments don't matter quite so much then.
 

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There is a small problem, however. The ST-60 system uses boat speed not speed over ground and compass course not COG to calculate true wind speed and direction even though both are available on SeaTalk. In a situation of current, drift is let oout of the calculation. I asked a Raymarien tech about this at a boat show and he gave me a B.S. answer as to why SOG and COG were not used.
 

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Raymarine is a division of Raytheon. The latter is a big supplier of high-tech military hardware to the the U.S. military. Things that make you go
Not for some time now, There was an MBO, its a public UK company and its share price has tanked in the last year.
 
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