Mount Wind Intrument Just Above the Split Back Stay?

[rardiH36]

At times I would just like to know how strong the wind is! But not important enough to get myself above the mast top to drill and mount the sensor. Nor to pay a pro the $110/hr going rate.

The original equipment Datamarine wind display is still mounted on the outside bulkhead next to my companionway. But the stuff on the mast top and the wiring down is long gone.

Has anybody mounted a wind sensor on the backstay? I never have seen one. For me I would do this just above the split backstay fitting. Advantage is I can just use my 15 ft folding ladder while at my berth to safely reach the height.

I expect that the mainsail might skew the results a bit. But I am more interested in knowing wind velocity rather than apparent wind direction --- since I can readily see that by looking up at the mast top windex.

Also with the simplicity of the install, I could first experiment with a ~$100 wireless home type anemometer and receiving station. The display could either be in the cabin, or I can affix -- with some weather protection cover -- on my pedestal.

Regarding one those hand-held devices. I don't want to go into the cabin to fetch. And with readings being taken at only 5-6 feet above the water and affected by null spots or vortexes in/around the cockpit, probably isn't too meaningful anyway.

I am a 100% inland waterway and a single day outing sailor. So a failure of a device intended for home use wouldn't cause an issue as it might for a boat doing extended Blue Water cruising.

Just an idea. Opinions?

 

[Bill1565]

Why bother? Listen to the radio or look at weather on your smart phone.

 

[rardiH36]

Why bother? Listen to the radio or look at weather on your smart phone.

Bill:

Maybe in normal locations your observation is pertinent, but on San Francisco Bay the wind can be blowing at 25kts with gusts +35 in one 0.5 x 1.0 square mile slocation (think "the Slot" west of Alcatraz Island where the Oracle AC72 had it's unfortunate incident last October. See link below). And at the same time can be blowing a terrifying 0kts just 1.0 miles away in Sausalito or 1.5 miles away in the lee of Angel Island or 2.0 miles away off the San Francisco waterfront at the Ferry Building Terminal. The VHF marine weather broadcast can't cope with our micro climates. Up until about a year ago, we could get off the internet the 9-minute-after-each-hour summary of average wind + max gusts on Angel Island. But the weather station went silent and remains un-repaired. The wind on the GG Bridge still is reported, but most often the velocity there is well under the conditions just 1/2 mile east where I most often sail.

http://www.google.com/imgres?imgurl...RD-qUY-XIcrwigL0joBo&ved=0CD4Q9QEwBA&dur=2474

 

[shemandr]

I would think that the air would be disturbed enough at the backstay to render the readings inaccurate. That's not to say useless - because in a relative sense they may be useful. But they probably wouldn't be useful to compare wind velocities anywhere but on your boat.
I think with experience on the water you can gauge wind velocities with enough accuracy by looking at the water condition, flags that are visible, the effect the wind has on the sails. And remember with the anemometers in the popular brands can be calibrated to read pretty much whatever you want. In the end you judge what the wind should be by reading the water, looking at flags ……...

 

[Doc_holiday]

I guess it depends on which direction the wind is coming from as to whether it would spoil the readings. How about on the bow rail?

 

[Bill1565]

Bill:

Maybe in normal locations your observation is pertinent, but on San Francisco Bay the wind can be blowing at 25kts with gusts +35 in one 0.5 x 1.0 square mile slocation (think "the Slot" west of Alcatraz Island where the Oracle AC72 had it's unfortunate incident last October. See link below). And at the same time can be blowing a terrifying 0kts just 1.0 miles away in Sausalito or 1.5 miles away in the lee of Angel Island or 2.0 miles away off the San Francisco waterfront at the Ferry Building Terminal. The VHF marine weather broadcast can't cope with our micro climates. Up until about a year ago, we could get off the internet the 9-minute-after-each-hour summary of average wind + max gusts on Angel Island. But the weather station went silent and remains un-repaired. The wind on the GG Bridge still is reported, but most often the velocity there is well under the conditions just 1/2 mile east where I most often sail.

http://www.google.com/imgres?imgurl=http://4.bp.blogspot.com/-4z-v4as2xJc/UH5Y-VOueGI/AAAAAAAAZ7Q/_1pthkk-N7g/s1600/GG12-SFOOCT-08899.jpg&imgrefurl=http://www.vsail.info/2012/10/17/photo-gallery-oracle-team-usa-ac72-capsize/&h=1066&w=1600&sz=249&tbnid=gq0pPJU5fqRBDM:&tbnh=90&tbnw=135&zoom=1&usg=__5fmI8WmbTztmsZatVrxSWjmOCtc=&docid=aljykMPlxFWeeM&sa=X&ei=RD-qUY-XIcrwigL0joBo&ved=0CD4Q9QEwBA&dur=2474

You initially said it wasn't important enuff to put at the mast head, where it belongs. Why bother to do it wrong?

 

[kloudie1]

How about something like this.. lets ya know how strong the wind is but is not a permanent mount..
http://www.weatherconnection.com/product.asp?itmky=441601&s=froogle&gclid=CLrOgLmDxLcCFU_ZQgod4CMAXg

 

[capta]

I doubt that you'll get more accurate readings on the system you are contemplating than your estimate of wind speed. It takes some time, but one can get pretty good at estimating the wind speed. Familiarize yourself with the Beaufort scale; the description of sea conditions, as well as wind speed. This ones kinda fun; http://www.howtoons.com/?page_id=150.

 

[alexco38]

Most of the time, the air flow at your back stay will be from the front as both sails trying to divert the air toward the stern. You would want wind sensor in relative "clean" air stream to monitor air movement.

 

[Stu Jackson]

rardi, after sailing for years with no wind instruments, our boat came with one. I rarely use it. I have been attaching our flag to the backstay since we first found out that when going downwind the flags in those silly backstaffs keep either hitting you in the legs or the head. So we attached our flag to the backstay, high enough up that even in no wind when the flag droops it's still over my head. Gives great direction and relative wind speed. Superb for surfing downwind through the Slot from the GGB to TI. I also keep my April to September reef on the mainsail and use our small jib during the summer. 0 wind doesn't matter what sails you have up. 2 knots? As you said, it will be 25 knots in a few minutes. As already mentioned, reading the water is helpful, and you already know the difference between the water/wind readings on ebbs and floods.

 

[rardiH36]

Thanks the inputs.

I think I'll go-ahead with this somewhat off the usual mounting location. Stu and Bill and others, I agree that condition of the water and the wind pressure on the face really are enough clues; and that for my type of sailing, a wind velocity instrument isn't a must. But like a lot of hi-tech navigation and communications stuff, would be fun to have. I would just like to be able to know with more certainty that I "banged around today in 35kts". Instead of just recounting "the winds really were strong out there". Yes, masthead is better, but for $100 or less and a few hours of simple installation, I could experiment with a ~15' high backstay mounted wireless anemometer/base station. The location may not be too useful on a close haul with the wind streaming off the leach when the mainsail is near the center line. But say on a beam reach and with the sail way out, maybe the reading might be a reasonable representation of true wind speed.

Stu: I also am in summer-time reduced sail area mode. Changed out the 135 Genoa for of a 90% yankee cut jib. And most of the time I leave the dock with the mainsail on the second reef point. With the jib out all the way and the mainsail reduced, I frequently still manage 7.5-8.0 kts water speed. Would do about the same with more sail, but my rudder would be hard over to leeward all the time to counteract the weather helm to maintain a straight course.

 

[Idratherbesailing]

I mounted a wind instrument on my backstay, made a mount out of aluminum bar and stainless cable clamps. Its about 10-12 feet off the water. Because I sail in summer, and in New Orleans you really need a good bimini, I could not see the windex on the top of the mast. So wind speed is not so important (you can watch the water to estimate that with some experience), but direction is. It works very well with regard to wind direction, even though I had to recalibrate the instrument since it is not facing in the direction intended when it comes from the factory. However, it is my unscientific and untested opinion, again from long experiece with a mast top mounted wind instrument, that the wind speed while correct for where it is mounted, is lower than would be if read from the same instrument mounted on top of the mast. This makes sense, as it is one of the same reasons we have to have twist in our sales, slightly differing wind speeds make for differing apparent wind direction and strength.

For me, it means thinking about reefing at 14-15 knts indicated instead of 17-18, so no big deal, as I sailed for several years without a wind instrument as it quit working, and I didn't want to go up the mast either...but it does work, just not the same way as a mast top mounted unit.

 

[rardiH36]

Hi Idratherbesailing:

Aha! I knew it! Someone has stepped forward to admit backstay location has been done!

Did you buy a normal marine wind instrument set? Or one designed for home/land use?

regards,
rardi

 

[higgs]

Knowing wind velocity is over rated unless you are seriously racing and have high tech sails. You certainly are not going to get accurate readings from behind the main which is why we mount those instruments out of the way of sails. Of course, wind velocity, and direction , is not always the same at the masthead as it is at spreader height.

 

[Idratherbesailing]

Backstay wind instrument

Hi Idratherbesailing:

Aha! I knew it! Someone has stepped forward to admit backstay location has been done!

Did you buy a normal marine wind instrument set? Or one designed for home/land use?

regards,
rardi

I had an old (came with a boat I bought in 2000) instrument new in the box, never needed it so I didn't install it on the boat I had then...lost that boat in Katrina, bought PERSEVERANCE after the storm, hence the name. Since it didn't cost me any additional and was still in the box, I though I would try it on the backstay...so far, for my cruising useage, it works fine. If I was racing, I would have gone to the trouble of putting it on top of mast, but all I needed really was direction, and it does seem to indicate wind direction fine. I am sure the sails effect it some, but there doesn't seem to be much if any difference on my boat in the direction of the windex on top of the mast and the indication from the wind instrument...I will say sometimes it bothers me the way it looks. I'll take a picture and post it next time I'm at the boat.

 

[rardiH36]

Re: Backstay wind instrument

Dear IdRatherBeSailing:

Thanks for replying. No need to take a picture. I can visualize I think. Yours being 2000 manufacturer, I expect you had to lead a wire along the back stay. I would be using a wireless wind velocity/direction sender. It will be white. And might even have small solar panel on it to keep a rechargeable battery charged. I think the appearance above the split back stay Y fitting will be OK.

 

[Idratherbesailing]

Took the Pictures, so here they are

I've taken them, so you might as well look. It does indeed have a wire running down the backstay. The only caution I would give you is make sure you an mount it in such a way that it indicates actual wind direction, as the way I mounted this one I had to recalibrate 180 degrees. I was able to do that with this one, but not all may work that way

 

[RichH]

Suggest you mount your wind instruments at the TOP of the mast.

Highschool 'science' books and most 'how to sail books' concerning 'how a wing or foil works' have been wrong since the time of the Wright Brothers - 1903. When sailing 'aerodynamically' - beating, close reaching, etc. the actual 'flow' of air contains a vectorial component of flow that 'circulates AROUND' the sail .... a component of forward air flow of air along the windward side of a sail/wing. Putting any 'wind instrument' anywhere near such 'complex' air flow will result in BAD (quite useless) readings.

With your wind instruments at the backstay you wont know if the actual air flow is forward, aft, or a partial mathematical combination of both directions. Certainly if the wind instrument is on a backstay relative to the windward side and to where the leech is positioned, there will be a flow component going in the forward direction and you'll have NO idea of how much this value is if you want anything even close to an accurate reading ... and will have to be added, or subtracted, from the 'gage' reading. ... and you also will have to modify/correct your reading depending on how many people are standing on the 'windward side' causing even more 'forward flow', etc.
Aerodynamics and the air flow 'around' sails is entirely 'not intuitive'. Putting any wind instrument in the zone of this complex air flow will result in very 'vague' and quite useless data.

Put your wind instruments at the very top, where there is the least 'upwash', little to no circulation air flow 'around' the sails and very little air flow disturbance from the shape of the oncoming boat and its sails .... pretty much straight-line flow coming TO the boat at the top of the mast. KISS ;-)

 

[rardiH36]

Hello RichH:

As always, I read and learn from your posts! Can't agree more that the proper place for wind velocity and direction sensors is at the top of the mast.

But this is a "let's-have-fun-maybe-it will-be-useful" type of project. Rather than risking dagger eyes from the spouse (from both the standpoints of cost/benefit financially and "don't risk your life going up the mast unless critical").

$100-150 for a home style wireless (with solar recharging at the send station) weather station with wind direction/velocity vs. ~$1400 + several hours at $110/hour for a rigger's mast climbing time to install a TackTick type of wireless marine instrument = ~$1800? That's almost 10% of the purchase price of my boat.

I'dRatherBeSailing looks to have mounted his sensors on the back stay maybe 10 ft above the waterline? Mine will be 20 ft. High enough to maybe be the average of what my sails are experiencing? I recognize that vortex's off the mainsail can skew significantly. But for me I will mainly judge the real wind velocity from the backstay mounted instrument when I am on a beam'ish reach with the mainsail let way out away from the back stay.

If this arrangement doesn't please when I am sailing ... at least I will have a weather station on my boat while at berth! Or I can take it home and install it there.

 

[gpd955]

Did you consider a handheld? I use one regularly and it works extremely well. It may give you the information you need and is very versatile. You won't get the 20ft you're looking for but something like this may fit your needs close enough.