Can the ST60+ wind instrument be adjusted to use COG and SOG

[AntarcticPilot]

I've got a Raymarine ST60+ wind instrument, installed in a complete set of ST60 instruments and a C80 plotter connected by SeaTalk. My paddle wheel log is much less reliable in East Coast waters that it was in Scottish waters - it gets clogged up very rapidly. This means that STW isn't reliable (i.e. it's wrong or absent much more often than its right!). The ST60+ wind instrument appears to rely on STW and heading to derive the true wind etc., and I can't find any way to change that in the user manual.

Is there any way to persuade the ST60+ wind instrument to use COG and SOG instead of heading and STW? I suppose a YAPP project to make a box that would use the COG and SOG to spoof the required sentences is feasible, but a) might have unforeseen consequences and b) is more work than I want to do!

I have done a Google search and come up blank, so I'm not hopeful!

 

[Old Harry]

Is this any help

http://forum.raymarine.com/forumdisplay.php?fid=117

I have found a phone call is often the best option

Apparent Wind
Apparent Wind Angle (AWA) and Apparent Wind Speed (AWS) are the default displayed data on dedicated wind instruments such as i60 and predecessors. This is directly measured by the masthead sensor and doesn't depend on any external data. Apparent Wind will vary depending on your boat's motion. As examples, if you're motoring at 10kn dead upwind into a 15kn breeze, your AWS will be 25kn and your AWA will be 0 degrees (wind on the bow.) On the other hand, if you're motoring dead downwind at the same speed, in the same wind, you'll see 5kn AWS from astern (180deg AWA.)

True Wind
What Raymarine refers to as True Wind (TWA, TWS) is always wind-over-water, not wind-over-ground (more on this below.) We calculate this from AWA and AWS, plus speed-through-water (STW, from a paddle-wheel or equivalent.) It's not possible to calculate proper True Wind from GPS speed (SOG.) If you're looking at your wind instrument and you have AWA and AWS but TWS is showing as dashes (-.-kn) then you don't have Speed data coming in. In addition to TWA and TWS, our recent multifunction displays and i70/i70S instruments also offer TWD (true-wind referenced to north rather than the bow.) This requires compass Heading as well as STW. We can't use GPS COG for this because COG is the direction you're moving, not the direction you're facing (which is what Heading measures.) Lighthouse 2 MFDs also require Heading in order to display TWA/TWS.

 

[RichardS]

This thread will explain all and provide you with the solution which will give you true wind and enable you to throw away the paddlewheel:

http://www.ybw.com/forums/showthrea...0-Tridata-instrumentation&highlight=true+wind

I have the SOG-1 but the SOG-2 is better: http://www.cruzpro.com/sog2.html

Richard

 

[flaming]

I've got a Raymarine ST60+ wind instrument, installed in a complete set of ST60 instruments and a C80 plotter connected by SeaTalk. My paddle wheel log is much less reliable in East Coast waters that it was in Scottish waters - it gets clogged up very rapidly. This means that STW isn't reliable (i.e. it's wrong or absent much more often than its right!). The ST60+ wind instrument appears to rely on STW and heading to derive the true wind etc., and I can't find any way to change that in the user manual.

Is there any way to persuade the ST60+ wind instrument to use COG and SOG instead of heading and STW? I suppose a YAPP project to make a box that would use the COG and SOG to spoof the required sentences is feasible, but a) might have unforeseen consequences and b) is more work than I want to do!

I have done a Google search and come up blank, so I'm not hopeful!

You should find that the ST60 instruments already do this, but they call the output ground wind. At least when displayed using a graphic head, not the standard analogue instrument.
http://www.busse-yachtshop.de/pdf/ray-ST60+_GraphicDisp_OH.pdf

See page 7.

Of course, the actual answer is that ground wind is really not very useful, especially on the East coast where tides (and therefore the tidal component of the wind) can be a significant part of the true wind you are using to sail.

Finding a way to keep your paddlewheel clean would be the better option.

 

[lw395]

....
Finding a way to keep your paddlewheel clean would be the better option.

Or getting your head around estimating true wind 'near enough' from your apparent wind.
Beating, true wind is pretty close to apparent-(70% of boat speed). Your yacht will be doing about 5 if it's small or about 7 if it's big, so take 4 or 5 knots off the apparent.
Running, add boat speed to apparent.
How often do you really make use of a wind speed number more acurately than that? And did the Raymarine box ever get it that accurate anyway?

A lot of the time, it's nice to go back to the basics of compass, telltales and apparent wind speed.

 

[AntarcticPilot]

You should find that the ST60 instruments already do this, but they call the output ground wind. At least when displayed using a graphic head, not the standard analogue instrument.
http://www.busse-yachtshop.de/pdf/ray-ST60+_GraphicDisp_OH.pdf

See page 7.

Of course, the actual answer is that ground wind is really not very useful, especially on the East coast where tides (and therefore the tidal component of the wind) can be a significant part of the true wind you are using to sail.

Finding a way to keep your paddlewheel clean would be the better option.

I don't have the generic display instrument, only the dedicated wind, speed, depth and compass displays, which don't have the plasticity of the instrument you point at.

 

[AntarcticPilot]

Or getting your head around estimating true wind 'near enough' from your apparent wind.
Beating, true wind is pretty close to apparent-(70% of boat speed). Your yacht will be doing about 5 if it's small or about 7 if it's big, so take 4 or 5 knots off the apparent.
Running, add boat speed to apparent.
How often do you really make use of a wind speed number more acurately than that? And did the Raymarine box ever get it that accurate anyway?

A lot of the time, it's nice to go back to the basics of compass, telltales and apparent wind speed.

I can, of course, do that, but not with much precision! And it's a mental step more than should be necessary. It's also not the wind velocity I'm interested in, but its direction; at low wind and boat speeds, small variations in the boat speed can cause large changes in apparent wind, and knowing the true wind is useful in trimming sails. Yes, I know I sail by the apparent wind, but if I'm planning a change of course, the true wind is useful.

 

[flaming]

I can, of course, do that, but not with much precision! And it's a mental step more than should be necessary. It's also not the wind velocity I'm interested in, but its direction; at low wind and boat speeds, small variations in the boat speed can cause large changes in apparent wind, and knowing the true wind is useful in trimming sails. Yes, I know I sail by the apparent wind, but if I'm planning a change of course, the true wind is useful.

But in places with strong tides, and light winds, ground wind and true wind will differ fairly substantially. And it is True wind that you need as a trimming aid, Ground wind is of very limited use for your intended purpose.

 

[lw395]

I can, of course, do that, but not with much precision! And it's a mental step more than should be necessary. It's also not the wind velocity I'm interested in, but its direction; at low wind and boat speeds, small variations in the boat speed can cause large changes in apparent wind, and knowing the true wind is useful in trimming sails. Yes, I know I sail by the apparent wind, but if I'm planning a change of course, the true wind is useful.

Beating, you know the true wind angle from your compass.
The rest of the time, how often do your instruments really tell you anything you didn't know?
Calculated true wind is riddled with errors.
The actual true wind varies from second to second and place to place, even over the space of a few tens of yards.

IMHO the biggest use of a windspeed indicator is running down to a mark, telling you how much sail you want for the next windward leg. On small boats with no windometer and no sail choices, we don't really miss the windometer.
I'd miss the log speed readout more for racing.

 

[flaming]

Beating, you know the true wind angle from your compass.
The rest of the time, how often do your instruments really tell you anything you didn't know?
Calculated true wind is riddled with errors.
The actual true wind varies from second to second and place to place, even over the space of a few tens of yards.

IMHO the biggest use of a windspeed indicator is running down to a mark, telling you how much sail you want for the next windward leg. On small boats with no windometer and no sail choices, we don't really miss the windometer.
I'd miss the log speed readout more for racing.

For us it's far more about getting to the top mark and knowing the TWA on the next leg, and therefore which spinnaker we want... This was especially crucial at Cowes this year, as with 20+ kts true, we could only hold the S4 up to circa 150 TWA, anything higher than that we needed the A5.

 

[lw395]

For us it's far more about getting to the top mark and knowing the TWA on the next leg, and therefore which spinnaker we want... This was especially crucial at Cowes this year, as with 20+ kts true, we could only hold the S4 up to circa 150 TWA, anything higher than that we needed the A5.

But you'd have known your TWA from your compass heading while beating, even if you needed to look at the two tacks to get your pointing angle. That is likely far more accurate than the Raymunging or Bullshit&Guesswork indications?

 

[flaming]

But you'd have known your TWA from your compass heading while beating, even if you needed to look at the two tacks to get your pointing angle. That is likely far more accurate than the Raymunging or Bullshit&Guesswork indications?

We have (inherited with the new boat) a top end B&G setup. It was absolutely spot on all week. If it said the next leg would be 130, it was 130. Such a nice change from the tactics the old boat had. No messing about, Navigator (owner) looked at ipad, asks it what wind angle next leg is, gives answer, select sail, round mark, hoist. Wasn't wrong once. Made a difference... Especially where we were about 5th around a mark that then had a tight kite leg in 24 knots. We knew we could hold the A5, so we were round and hoisted before the boats in front had made up their mind.

 

[prv]

But you'd have known your TWA from your compass heading while beating, even if you needed to look at the two tacks to get your pointing angle. That is likely far more accurate than the Raymunging or Bullshit&Guesswork indications?

Why wouldn't the computers do exactly the same thing, with more copious and precise maths?

Pete

 

[lw395]

Why wouldn't the computers do exactly the same thing, with more copious and precise maths?

Pete

The true wind indication is calculated from apparent wind angle (with errors, including due to the boat heeling), apparent wind speed (with error), heading (with the same error as simply looking at the compass), boat speed (with errors), neglects or guesses error from leeway, and all averaged over some period. It's great when it works well, when all the calibration is spot on.
But if I'm sailing my dinghy and the tacktick is scoring 275 on one tack and 355 on the other, I'm pretty sure the true wind is 315.
I could even correct that for sailing a couple of degrees fatter on Port because the waves are at a bad angle.

Where instruments would help is when you've got a big kite up and it's hard to tell whether your speed increase is due to the wind heading or gusting or a bit of both. But the paddlewheel would tend to struggle when half the hull's out of the water...

Aside from the fact that The True Wind varies all the time anyway, most people's instruments are not accurate enough to read anything like the same true wind on different points of sailing.

But people do like their electronic toys.