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PostPosted: Thu Oct 01, 2015 9:11 pm 
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Wind angle measurement from the masthead on a rotating mast sailboat has formerly required a mast rotation sensor to calculate relative wind angle. The mast rotation data along with electronically measured wind direction are fed to a computer which calculates wind angle. These devices are relatively expensive and/or require wired connections to the processor.

Dr. Craig Summers and his team at SailTimer http://www.sailtimerwind.com have developed a wireless Wind Instrument which is capable of measuring both wind speed and direction independent of mast rotation.

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A compass is housed within the directional arrow.

The device is lightweight and powered by a solar rechargeable lithium battery. The electronics are potted in some sort of transparent polymer sealing it from the elements. Communications is via Bluetooth 4 to the SailTimer iOS app via an intermediary SailTimer API app.

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Wind angle is calculated from the Wind Instrument direction and the GPS heading from the app.

The iOS app is quite sophisticated and contains SailTimer's proprietary TTD (Tacking Time to Destination) algorithm for determining ETA based on current tack and will determine the optimal tack. It will even calculate polar plots for the boat! There is a lot more that the app can do and is described at http://www.sailtimerapp.com.

The device will also wirelessly export NMEA 0183 to the soon to be released Mini Server which then passes the data to the wired NMEA input of compatible chartplotters. I plan to implement this using a Garmin 527xs which can utilize the NMEA 0183 MWD sentence that the Mini Server outputs.

For the mounting, I cobbled together some Railblaza parts to create a masthead quick release.

After countersinking holes in a Railblaza spacer disk, I attached the disk to the masthead cap using SS sheet metal screws.

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Next, a small Railblaza Starport was attached to the disk using SS hardware and blue Loctite.

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As an aside, here's an obvious use:

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For the Wind Instrument, I attached a male Railblaza Star to the Wind Instrument base using a SS M6 screw and Loctite.

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This video shows the SailTimer app reading data from the Wind Instrument:



I have sailed with the device once, but not masthead mounted. My main criticism is that the wind gauge/speedometer does not show the wind direction relative to the boat in magnified view. However, with the wind gauge in default (smaller) view, a wind direction arrow shows wind direction relative to the boat heading - it's just tough to read the wind data. Hopefully, this will be addressed soon in an update.

I'll post more information once I've had a chance to sail more and thoroughly test the hardware.


Last edited by scc on Sat Oct 03, 2015 5:03 pm, edited 1 time in total.

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PostPosted: Fri Oct 02, 2015 4:17 am 
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I just have trouble seeing how all that complication and technology can improve on the simplicity of a wind-indicator arrow like this.

No electronics, and it just slides into a clear plastic tube mount.
Image

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PostPosted: Fri Oct 02, 2015 10:19 am 
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tonystott wrote:
I just have trouble seeing how all that complication and technology can improve on the simplicity of a wind-indicator arrow like this.


It's analogous to driving with a paper map vs. a GPS - both work but with different pros and cons.


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PostPosted: Fri Oct 02, 2015 10:31 am 
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I mounted by Davis spar fly wind indicator similarly. Quite happy with the simplicity of just a simple wind indicator.

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PostPosted: Fri Oct 02, 2015 11:13 am 
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scc wrote:
tonystott wrote:
I just have trouble seeing how all that complication and technology can improve on the simplicity of a wind-indicator arrow like this.


It's analogous to driving with a paper map vs. a GPS - both work but with different pros and cons.

I don't think that is a valid comparison at all, these are not America's Cup boats after all, but the masthead wind indicator will be easily as accurate as any other method. I don't mind looking up ftom time to time :D :D

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PostPosted: Fri Oct 02, 2015 1:58 pm 
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Oh, I dunno... The gadget freak in me loves it! :mrgreen:

However, I really dislike this tendency for everything new to use an app on my phone for an interface. That's okay for things I rarely need to work with, or possibly even things I'm usually working with in a calm, relaxed setting, but not when I'm out in bright sunlight being bounced around - especially if I'm actually under way - and I'm trying to use and see a touch interface through an additional layer of plastic since the phone is in a dry bag!

Not to mention keeping my phone's screen on eats the battery fairly quickly, but if I turn off the screen now I have to slide-to-unlock then type in my code (again, much more troublesome through the dry bag especially if my hands are wet) before I can see the display again.

I'd rather have a dedicated "dashboard" display that I could quickly look down at but there's precious little room for that on a TI. I have my Lowrance mounted on the left side of the mast, would like to put a simple LARGE compass ball on the right. It might be sufficient to pump the data into the Lowrance, though I think mine only outputs NMEA. Even if it did read, I think the most I could do is add numbers to the screen, I wouldn't have any nice graphical display.

Hm... Maybe that's another project I could build for the Raspberry Pi I keep threatening to install...? :lol:

Just had one last thought, I presume the OP's device is intended for use on a sailboat that's kept outside all the time. I wonder how it handles a dead battery? If it draws the lithium battery down too far before shutting off the battery may not last very long when used with a TI where it gets packed away between uses and doesn't see the sun for a week or more at a time... (Maybe there's a hardwired power switch?)


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PostPosted: Fri Oct 02, 2015 4:07 pm 
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RandomJoe wrote:
Oh, I dunno... The gadget freak in me loves it! :mrgreen:

However, I really dislike this tendency for everything new to use an app on my phone for an interface. That's okay for things I rarely need to work with, or possibly even things I'm usually working with in a calm, relaxed setting, but not when I'm out in bright sunlight being bounced around - especially if I'm actually under way - and I'm trying to use and see a touch interface through an additional layer of plastic since the phone is in a dry bag!

Not to mention keeping my phone's screen on eats the battery fairly quickly, but if I turn off the screen now I have to slide-to-unlock then type in my code (again, much more troublesome through the dry bag especially if my hands are wet) before I can see the display again.

I'd rather have a dedicated "dashboard" display that I could quickly look down at but there's precious little room for that on a TI. I have my Lowrance mounted on the left side of the mast, would like to put a simple LARGE compass ball on the right. It might be sufficient to pump the data into the Lowrance, though I think mine only outputs NMEA. Even if it did read, I think the most I could do is add numbers to the screen, I wouldn't have any nice graphical display.


Couldn't agree more. I use an iPad mini in a Lifeproof case. Battery life is much better than the iPhone. The screen glare is a problem though.

The Mini Server will allow output to compatible chartplotters. Here's the screen from my Garmin 527xs that would display the wind data:

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While this solves the battery and glare problem, only the iOS app allows determining Tacking Time to Destination and Polar Plots.

RandomJoe wrote:
Just had one last thought, I presume the OP's device is intended for use on a sailboat that's kept outside all the time. I wonder how it handles a dead battery? If it draws the lithium battery down too far before shutting off the battery may not last very long when used with a TI where it gets packed away between uses and doesn't see the sun for a week or more at a time... (Maybe there's a hardwired power switch?)


No hardwired switch. It supposedly sleeps quickly to conserve power. This is something that I'll be monitoring.


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PostPosted: Fri Oct 02, 2015 4:20 pm 
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Wow! Complication run wild and on these simple boats. Personally, I'm keeping that space atop the mast available since I may be getting the Hobie Reacher sail for my AI 2 when it becomes available.

Some people like to tinker with their boats (they're not called a "black hole," or is that a "money hole", for nothing). More power to them, it is just not the direction I'm going. I like a practical, functional boat--the simpler the better.

scc--most (all?) hand-held gps units will give you "time to your destination" and "miles to destination" from any point. Isn't that the same as "tacking time?" Why do you need polar plots?

Keith

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Last edited by Chekika on Fri Oct 02, 2015 8:48 pm, edited 1 time in total.

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PostPosted: Fri Oct 02, 2015 6:03 pm 
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I prefer simple most of the time. (One reason I actually enjoy taking my boring 'ol Pungo out after using the TI - it's so much SIMPLER!)

However, the gadget freak must be satisfied occasionally. I was adding stuff to my bicycles for years before kayaking, not to mention cars...

I used to be fairly heavily into amateur radio and had an HF rig with auto-tuning antenna I could use on the bike at one point. Weighed a ton and hard on the radio thanks to our rough roads so I didn't use it much but remember one fine early morning cycling around the lake listening to the Navy Net on 40M - I even checked in and talked with the net control op while sitting beside the lake just to see if it would work! :mrgreen:

Not planning on any ham rigs on the kayaks, unless I feel like putting an APRS tracker on one. Might be funny to see what people say when they see a kayak show up on the map moving up the river...

The Raspberry Pi for the TI started with a couple of ideas. First I wanted to log all the NMEA data from the Lowrance. The data it exports to SD card doesn't include the sonar data (or I haven't figured it out yet) so I thought I'd just log it myself using the NMEA output then format the data into a .kml file so I could have plots on Google Earth that showed depth data - or even water temp - on the map.

I also thought about a simple "light pole" as a depth warning, maybe a green/yellow/red LED mounted atop the Lowrance that I could set for caution/warning depths so if I'm flying along under sail and not paying attention to the Lowrance the LED would give an easily-seen indication that I might be about to run aground.

Having sailed various lakes for a while now I don't think this would be as useful as I thought, so... Now I'm thinking "technicolor kayak"! :lol: Put some RGB LEDs inside the hull and change the color of the kayak depending on water depth or whatever. The yellow hull is relatively translucent, not sure how the colors would work. A dune hull may be better, though my Outback doesn't seem very translucent. (Yeah, only really good for after-dark but would be fun at our Full Moon Paddles.)

Just goofy projects to tinker and be silly with... :mrgreen: 90% of the time I wouldn't even bother with them but occasionally...


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PostPosted: Fri Oct 02, 2015 7:48 pm 
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Accurate wind instruments are vital for night sailing on bigger sailboats, but I would bet 90+ percent of sailors tend to ignore them during the day, prefering the "wind-in-the-face" analogue experience.

Having said that, I thoroughly enjoy the screens of my Lowrance chartplotter and my Android Navionics app, but only for coarse-grain navigation.

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PostPosted: Sat Oct 03, 2015 5:18 pm 
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Chekika wrote:
scc--most (all?) hand-held gps units will give you "time to your destination" and "miles to destination" from any point. Isn't that the same as "tacking time?" Why do you need polar plots?

Keith


These parameters aren't accurate for sailboats since, much of the time, the destination is not directly ahead. For a very detailed explanation, see here: http://www.sailtimerapp.com/VMG.html


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PostPosted: Sat Oct 03, 2015 7:04 pm 
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scc wrote:
Chekika wrote:
scc--most (all?) hand-held gps units will give you "time to your destination" and "miles to destination" from any point. Isn't that the same as "tacking time?" Why do you need polar plots?

Keith


These parameters aren't accurate for sailboats since, much of the time, the destination is not directly ahead. For a very detailed explanation, see here: http://www.sailtimerapp.com/VMG.html

I read that "explanation", but it only criticised VMG to the mark and VMG to the wind, but only offered a statement that its product somehow overcame these issues. Is there another document which actually explains how the product actually achieves its results?

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PostPosted: Sat Oct 03, 2015 7:23 pm 
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Hand-held GPS units give you Distance to Destination on any tack. Your destination does not have to be straight ahead. These are small computers. To calculate VMG or distance (to your destination) on any tack is a simple calculation.

Keith

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PostPosted: Sat Oct 03, 2015 10:46 pm 
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Chekika wrote:
Hand-held GPS units give you Distance to Destination on any tack. Your destination does not have to be straight ahead. These are small computers. To calculate VMG or distance (to your destination) on any tack is a simple calculation.

Keith


I should have been more specific. GPS distance to destination is accurate regardless of heading. VMG is a simple calculation. However, given constant conditions (wind speed, direction, current, leeway, etc.), VMG to destination will constantly decrease on any given tack as the boat sails farther and farther from the destination. Therefore, VMG is not a very useful indicator of optimum tacking angle.

Good explanation here: http://sail.navas.us/why-vmg-matters.html

Keith and tonystott: I didn't start this post to promote this product. Thus, I don't feel I need to defend it or provide documentation on how it functions. I have never stated that it is better than any other device - only different. As I stated, I have very little experience with it. I'll post my experiences and hope that it lives up to what it promises. Maybe other folks on the forum will appreciate the information.


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PostPosted: Sat Oct 03, 2015 11:07 pm 
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A really neat job with the mounting...

The only comment I would make is that you may want to see if you can squeeze some theaded screws & nuts
in there to hold that top plate, rather than relying on self-tappers.

Great work!

Mike.


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