MacGregorSailors.com

jschrade wrote:Not to rain on your parade but ... it will not be accurate from the stern. These are installed on top of the mast for good reason, there's no obstructions and you get a reading of the wind 30 some feet in the air which is different than what you are reading on the deck.

Well, it's not that simple. The boat's motion and heeling are amplified greatly at the top of the mast, and an anemometer will measure side-to-side wind at the masthead caused by the ship's motion. So, in effect, it's not perfectly accurate at the masthead either. The Airmar PB200 has a gyro to compensate automatically for this, but the Maretron does not. The Airmar is 2x the price however.

I'll test the WSO100 at the bow pulpit, the masthead with the mast bracketed to stop movement, at the stern, and at the stern atop a pole, and report the various inaccuracy problems.

Have you tried Beano? http://www.beanogas.com/?redirectfrom=w ... o.net%20R- I find it helps with my wind sytem!

jschrade wrote:

Currie wrote:A simple way to find out if the down-wash from the main is a problem for a stern-mount, is to try it out with a simple Davis windex and see if trimming the main disturbs it. Scores of sailors cross oceans with servo-pendulum windvane steering that is always mounted on the stern. They steer the boat just fine.

~Bob

The Weather Vane systems mentioned are not meant to measure wind or direction. They are meant to maintain a relative heading to the wind or in other words steer the boat. I would be impressed to see one of those on a 26M!!!!!

Jim

The manufacturers of the "Cape Horn" wind-vane system has a list of different boats on their website, and they show the dimensions for mounting their "Jean-du-Sud" model on a MacGregor 26. But it costs nearly $3500 and it's way more trouble than my Raymarine X-5 wheel pilot ($1359 from We$t Marine).

Also, it's worth noting that wind-vane self steering systems are best for long passages - ocean voyages - where you might sail the same tack for hours or even days on end. Our boats are too light to be sea-kindly for such a passage. I will have a wind vane on my next boat, but it will something like a Crealock 34 - a vessel that's built for ocean cruising - and that's what I will be doing with it.

David Mellon wrote:Have you tried Beano? http://www.beanogas.com/?redirectfrom=w ... o.net%20R- I find it helps with my wind sytem!

I would say something about "old fart" but that one smells pretty fresh from here!

I have Raymarine St60 installed on stern mast. In spite all expectation works just excellent in all wind directions. Integrated with Raymarine autopilot, Garmin 525s and electronic charts inside the cabin. Sea-talk/NMEA converter from Raymarine. Please note you will need log for correct calculation of true wind. I'm using St40 transom mount transducer.

Andrey-314 wrote:I have Raymarine St60 installed on stern mast. In spite all expectation works just excellent in all wind directions. Integrated with Raymarine autopilot, Garmin 525s and electronic charts inside the cabin. Sea-talk/NMEA converter from Raymarine. Please note you will need log for correct calculation of true wind. I'm using St40 transom mount transducer.

That truly is a secondary mast! It's what I intend to do, but I will need to be able to drop it easily for trailering.

Of course you can - for me it takes 5 minutes to screw out 3 bolts and disconnect one shroud. I found one picture you can see general idea.

One hole for all cables (VHF, anchor light and wind wane). Device have been checked in 30 knots wind and rough seas - found reliable enough. I repeat there was no cheat readings inoticed during last year season, I've passed around 2000nm in total last year. I wouldn not recommend Rotaveca sensor (cheaper) as its reeadins are not reliable in slow wind and any hit during installation or mast movement can cause serious mulfunction of wind direction sensing element.
Not good picture but below you can see trailering position of the aft mast:

Andrey, you've convinced me--that's what I'm doing.

Your welcome Will be glad to help if you will need any further advice /detailed pictures. As soon as my boat will be placed back to trailer (see my previous post ).

Here's what I did:


http://www.macgregorsailors.com/modt/index.php?view=701


I use the GPS ground speed in place of a log for the wind system calculation for true wind. This only works if there's no current.

baldbaby2000 wrote:Here's what I did:


http://www.macgregorsailors.com/modt/index.php?view=701


I use the GPS ground speed in place of a log for the wind system calculation for true wind. This only works if there's no current.

Nice! What embedded processor did you use, Arduino or a derivative? Did you use the on-chip CAN bus interfaced to NEMA 2000, or did you use a serial port interfaced to NEMA 0183? I'd like to do a bunch of my own re-processing of NEMA 2000 data and it looks like a very standard current bus to me so I'm about to break out my soldering iron...

I want to go with mast-top mounted Maretron (NMEA 2000) eventually combined with an autopilot. I'm not sure how well a potentiometer would hold up in the mast base to account for the rotation on my . Wouldn't it be simpler overall to run a conduited rod up the mast, attached to the swivel bolt somehow, and just let the mast turn around it while letting the sensor remain fixed?

Ross

Nice! What embedded processor did you use, Arduino or a derivative? Did you use the on-chip CAN bus interfaced to NEMA 2000, or did you use a serial port interfaced to NEMA 0183? I'd like to do a bunch of my own re-processing of NEMA 2000 data and it looks like a very standard current bus to me so I'm about to break out my soldering iron...

I used an 8051 made by Cygnal (now Silabs I think). It has built-in UARTS for communicating with the units. I added a Garmin GPS module that puts out standard NMEA 0183 sentances and put it all in one box and programmed a drift alarm too. I got an Arduino but haven't done much with it yet.

Crikey wrote:I want to go with mast-top mounted Maretron (NMEA 2000) eventually combined with an autopilot. I'm not sure how well a potentiometer would hold up in the mast base to account for the rotation on my . Wouldn't it be simpler overall to run a conduited rod up the mast, attached to the swivel bolt somehow, and just let the mast turn around it while letting the sensor remain fixed?

Ross

Maybe that would work in concept but there are wires and foam in the mast plus you're adding weight. The potentiometer is protected and has been reliable but the unit I have is designed for it and I'm not sure if that's true for other units. Another thought would be to have a template on the display with two wind direction scales on it: one for a port tack and one for a starboard tack. That assumes the mast rotates the same angle each time. The normal display will be off by whatever the angular rotation of the mast is so the template would correct for that. That idea probably would complicate your autopilot plans.

baldbaby2000 wrote:Maybe that would work in concept but there are wires and foam in the mast plus you're adding weight. The potentiometer is protected and has been reliable but the unit I have is designed for it and I'm not sure if that's true for other units. Another thought would be to have a template on the display with two wind direction scales on it: one for a port tack and one for a starboard tack. That assumes the mast rotates the same angle each time. The normal display will be off by whatever the angular rotation of the mast is so the template would correct for that. That idea probably would complicate your autopilot plans.

I thought about the extra weight of the conduit and didn't figure it would be any different from what others have done with running cabling from the top. But including a thin aluminum rod inside without adding too much extra mass would probably twist excessively as well as chafe on any wires inside. I will be trying the conduit mod next week and will try and determine if the above is true. Attempting to do two pipes down the mast is probably outrageous.
The mast seems to rotate variably according to point of sailing. I would have thought they could be slaved to a fluxgate as a heading reference.Perhaps the high stern mount is the simplest way to go given the complications of the .

Ross