wind direction indicator for auto pilot

[BOAT]

I notice that many people run 3/4 inch pvc pipe all the way up their mast for wiring stuff. Would it be possible to just secure the bottom of the PVC pipe to the threaded end of the mast bearing at the bottom and let about one inch of the pipe stick out through a hole in the top of the mast cap and just mount our wind instruments on that?? (As the mast rotates it would not rotate the PVC pipe becasue the PVC pipe would be secured to the end of the threaded stud that holds the mast bearing).

Am I making sense?

The pipe would not bind or twist at the top of the mast as long as the hole was big enough to let the pipe go out the top, right?

I sort of wanted to get into that mast to instal an internal main halyard someday too, (might need a chicken, duck, pecker, bird turkey, whatever "head" to do that).

I dunno, I'm not the sharpest knife in the drawer, maybe someone will figure it out. There has to be some way to do it.

[kadet]

Aren't't the masts full of foam floatation? And would it not be a PITA if you trailer. I get what you are saying BOAT and the principle sounds like it should work as the bolts welded to the foot and does not rotate with the mast.

[beene]

The Raymarine i40 rotavecta does require linearization calibration to determine its heading and will report inaccurate wind direction with a rotating mast. The linearization calibration process is described in the i40 installation guide, and it very specifically is determining the mounting point heading line.

You WILL be able to weathervane with it using an autopilot because you can weathervane with a completely uncalibrated wind instrument or one that is not linearized--It doesn't matter if the wind direction is "correct" when you weathervane, it only matters how it changes relative to your tack, and the MacGregor mast tends not to move around much on a tack.

But the instrument will not report correct wind angles compared to heading on a rotating mast.

Yes, the i40 does require initial calibration, I did not even complete 1 full circle and it said it was done.

I mount my rotovecta on my mast arch as seen in my videos.
Same location most folks do, Delevi, Highlander, etc, all using Raymarine Autopilots as well.

So, if being at the top of a rotating mast would screw up the readout, my apologies for misunderstanding the network process.
I thought the network was comparing all info to determine the most accurate representation of what was really going on.
On the screen of the i40, it has the outline of a boat that stops where the transom would be.
At the ends of these lines is the no go zone on a sail boat while sailing.
Basically 30 off apparent
When I am on a beat, my wind line comes right to that edge on each tack.
If I head up further, bringing the wind direction indicator past that point, the sails start to stall.
So it would appear that my i40 is calibrated correctly.
If it were at the top of the rotating mast, as per what you point out, might not work as well, but I have no idea as mine is not there.

Again, sorry for misleading anyone

In my mind, which is not saying very much, I did not think it would matter much where the rotovecta was installed.

I did not see the point in installing it up there as I trailer all the time and none of my friends put theirs up there and everything seems to work just fine.
I have been extremity pleased with my autopilot and now i40 working together.
Single best mod I have done on my M.

Cheers

G

[BOAT]

Aren't't the masts full of foam floatation? And would it not be a PITA if you trailer. I get what you are saying BOAT and the principle sounds like it should work as the bolts welded to the foot and does not rotate with the mast.

The stud that the mast bearing bolts to is welded on the plate - the plate goes with the mast when you trailer - so there is no interference with the lowering and trailing stuff.

The stud sticks out and the mast is bolted to that stud with a bearing in between. Since the stud does not move - it would be a great place to mount an instrument. The problem is that the stud is inside the mast. whatever you attach to that stud is not gonna rotate with the mast.

As for the foam and stuff, yup - that's a problem - all the foam would need to be removed. I don't even know how to do that (I have never even seen the foam, so I can't say how to get rid of it).

Yes, it will take a brain much bigger than mine to figure this out.

[mastreb]

Hi Beene,

I'm sorry--that's my misunderstanding. I thought you'd put the rotavecta on the mast. If if its on the mast arch, the readings will be accurate excepting a few degrees around a beam reach on the one tack that the rotavecta is on. Basically only when leech of the mainsail is pointed directly at the instrument. Mast arch is good enough for most purposes.

There's no where you can put a wind instrument on a 26M that is free of problems. I only chose the bow because running is the point of sail I'm willing to have the instrument be inaccurate on.

There's a wind instrument from flyorsail.com that has a derotator built into the mast and designed for the Mac 26M, but I'm not sure its actually available.

I think I'm settled on the simplest solution being mechanical: A "hinge" rivited to the forward part of the mast top, with the wind instrument mounted forward on a hinged arm. Then the NMEA 2000 cable would be brought forward to the bow pulpit as if it were a 2nd forestay. The cable will keep the hinged arm pointed along the heading as the mast turns. I'd put a plug coupling at the bow pulpit so you could disconnect the cable when you lower the mast.

[beene]

Hi Beene,

I'm sorry--that's my misunderstanding. I thought you'd put the rotavecta on the mast. If if its on the mast arch, the readings will be accurate excepting a few degrees around a beam reach on the one tack that the rotavecta is on. Basically only when leech of the mainsail is pointed directly at the instrument. Mast arch is good enough for most purposes.

There's no where you can put a wind instrument on a 26M that is free of problems. I only chose the bow because running is the point of sail I'm willing to have the instrument be inaccurate on.

There's a wind instrument from flyorsail.com that has a derotator built into the mast and designed for the Mac 26M, but I'm not sure its actually available.

I think I'm settled on the simplest solution being mechanical: A "hinge" rivited to the forward part of the mast top, with the wind instrument mounted forward on a hinged arm. Then the NMEA 2000 cable would be brought forward to the bow pulpit as if it were a 2nd forestay. The cable will keep the hinged arm pointed along the heading as the mast turns. I'd put a plug coupling at the bow pulpit so you could disconnect the cable when you lower the mast.

Hi Mastreb

Highlander built a plate that mounts on the top of the M mast
He runs a back stay off of it
And it is stationary, when the mast rotates, it does not
You could mount a wind instrument on top of that plate
Problem solved
Also, if I did that, I would run the wire down the inside of the mast
Easy enough to get through the small amount of foam in there
John has accomplished that as well

As for the location I am using, the only time the boom is pointing towards the rotavecta is on a starboard tack.
And even then, the readout seems to be consistent.
When on a beam, the boom is no where near it on either tack.

G

[BOAT]

Okay, so, what IF, (a big IF), IF, I were to mount the wind instrument on the aft mast arch, would it be better if i had it in the middle? (There is a way i can mount it in the middle without interfering with the operation of the mast crutch, just take that as truth and trust me on it - I already have that issue figured out) - so I can indeed mount right IN THE MIDDLE of my mast crutch, so that leaves another question,

HOW HIGH in the air to I mount the wind instrument?

[kadet]

Okay, so, what IF, (a big IF), IF, I were to mount the wind instrument on the aft mast arch, would it be better if i had it in the middle? (There is a way i can mount it in the middle without interfering with the operation of the mast crutch, just take that as truth and trust me on it - I already have that issue figured out) - so I can indeed mount right IN THE MIDDLE of my mast crutch, so that leaves another question,

HOW HIGH in the air to I mount the wind instrument?

Higher the better

By mast mount PITA I meant either leaving or fitting the anemometer without breaking it every time you lower/raise mast.

[BOAT]

Higher the better

By mast mount PITA I meant either leaving or fitting the anemometer without breaking it every time you lower/raise mast.

Oh yeah Kadet - your absolutely right - I gotta say that even if I could put it on top of the mast the idea of taking it off every time is definitely a bit problem too - I see where you are going now.

So, if i do go off the aft I notice that the advice I get from you guys with the 'fully loaded radar arches' is: "The Highlander the better" so that will actually go well with the mast arch mod i am just starting on.

((I am going to modify the mast arch with yet another folding contraption mod to increase it's height when i want it higher, but when I don't want it higher it will be the same height as it is now.
- - - (don't ask, I have my reasons) - - -
the new arch will have the ability to hold instruments and even solar panels in it's various positions but still fold down low for trailering)).

I know I know, sounds crazy - I will send pictures.

[kurz]

well I found some more information here
http://www.sailtimerwindvane.com/

should actually solve our problems becouse the wind is mesured with a compass.

So just you have to get a connection to the plotter. But have no wires to the mast etc. that sounds easy?

[mastreb]

well I found some more information here
http://www.sailtimerwindvane.com/

should actually solve our problems becouse the wind is mesured with a compass.

So just you have to get a connection to the plotter. But have no wires to the mast etc. that sounds easy?

I went through the calibration procedure for this device, and unfortunately it does have to be fixed-mounted with it's arrow pointing to the head of the boat, which means that it does not sense heading itself.

The right solution is an anemometer with its own heading compass that it can reference. This would also allow it to work with no calibration procedure or directional mounting preference. Unfortunately nothing like that exists.

[kadet]

well I found some more information here
http://www.sailtimerwindvane.com/

should actually solve our problems becouse the wind is mesured with a compass.

So just you have to get a connection to the plotter. But have no wires to the mast etc. that sounds easy?

I went through the calibration procedure for this device, and unfortunately it does have to be fixed-mounted with it's arrow pointing to the head of the boat, which means that it does not sense heading itself.

The right solution is an anemometer with its own heading compass that it can reference. This would also allow it to work with no calibration procedure or directional mounting preference. Unfortunately nothing like that exists.

I must be thick I cannot see how a known heading will solve the variable mast angle for the wind-vane. Without a fixed reference (either fixed mast or knowing the mast angle to subtract or add) how does the sensor know the true angle?

E.G. Heading true north for easy maths for me

Heading 0 Mast Fixed Straight 0 wind-vane reading 15 port displays 15

Mast rotates

Heading still 0 Mast now points 10 port wind-vane will now reads 5 without knowing mast is pointed 10 it displays 5.

The Wind-Vane does not give a hoot about the compass heading as all it calculates is the angle port or starboard from the bow of the wind passing by. It needs either a fix position relative to the bow or the variable angle from the bow. I don't how knowing the heading will give that variable mast angle, or am I missing something

[mastreb]

Hi Kadet,

Instead of sensing relative wind (wind angle to boat heading), this anemometer is sensing true wind (wind angle to true north) without caring what the boat's heading is. That's why neither boat heading nor mast angle would matter.

But you are correct in that there's still not enough information to calculate true wind, you would also have to know the boat's speed-over-ground so you can factor that out.

Which means the anemometer would either have to be connected to the NMEA-2000 bus or contain its own GPS. Presuming it also contains its own GPS, it has all the necessary information to factor out speed to calculate True Wind and heading to report apparent wind. While that is a lot of electronics, it could all be solid state, and the single device could also act as a GPS input to the NMEA bus for a better mast-top GPS.

Matt

[kadet]

Yep I get all that, I think

Still think without a fixed wind-vane regardless you are going to need a goniometer as the vane will not know its orientation and not be able to factor in the variance. But I have a fixed vane and am beyond the point of worrying as geometry was not my strong point.

[kurz]

here the anwer from sailtimmer:

"Yes, the new SailTimer Wind Instrument™ has a digital compass right on the wind direction arrow, so it works with rotating masts. It doesn't matter if your mast rotates, the wind direction arrow still knows which way it is facing.

The new product does not have a base unit because it can transmit directly to mobile devices. However, there is going to be an accessory box that allows you to receive the wireless signal, and then send the wind data on with a wire using NMEA to your normal chartplotter.

The price of the accessory with the NMEA plug is not known yet."

Sounds goot, however we need practical expoeriance and price info for the whole set incl. wiring box for the plotter.