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Old 29-05-2012, 04:13   #1
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AP Steering to Wind Angles?

For those of you with auto pilots that can steer to wind angles, how good are they? Aside from the redundancy issues, do they make the humble windvane irrelevant?
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Old 29-05-2012, 04:24   #2
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Re: AP steering to wind angles?

My Auto pilot consumes energy while my Monitor wind vane works tirelessly without "food". I use the AP under power and the wind vane under sail if I had to give one up it would be the AP.
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Old 29-05-2012, 05:38   #3
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Re: AP steering to wind angles?

Quote:
Originally Posted by Eleebana View Post
For those of you with auto pilots that can steer to wind angles, how good are they? Aside from the redundancy issues, do they make the humble windvane irrelevant?
The autopilot will steer to wind angles very well, better than a wind vane, particularly in light airs.
The power consumption of modern autopilots is pretty low, but there is a lot to said for redundancy. A good solution is to fit two autopilots, with the multitude of electrical generating options available these days this is ( almost ) as reliable as an autopilot and wind vane. The main concern is lightening strike wich could take out both autopilots. A wind vane can also double as an emergancy rudder.

Good under deck autopilots have become so reliable that one is good enough for most boats, and wind vanes are disappearing from crusing boats.
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Old 29-05-2012, 12:57   #4
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Re: AP Steering to Wind Angles?

Well everything is a compromise, unfortunately. The pros and cons for installing a vane to my boat (42' centre cockpit with hydraulic steering and a long sugar scoop)

Pros
1. Redundancy (a big one) carrying a spare pump won't help me much if the failure is
a lightening strike, electricity failure or rudder problem.
2. Does not require electricity (I can run the motor for an hour anyway)
3. Quiet-my pillow will be directly above the ram (a huge deal)

Cons
1. Cost (about $7000 for the auxiliary rudder Flemming or Hydrovane in Oz)
2. Cannot carry a dingy on davits and there is no room on foredeck, so I'll
probably have to carry a roll-up which is not my preference.
3. It will make a huge mess of the swim platform

Hmmm, I think I've answered my own question. I just don't like the answer. Is there anything else I should consider?
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Old 29-05-2012, 13:14   #5
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Re: AP Steering to Wind Angles?

I found them pretty useless downwind (broad reach and running) in any realistic seas running (on monohulls). One look at what the wind instrument is doing sets the record straight. Less wind and more seas is the worst combo then. This issue is less pronounced on cats.

There is a sensor that removes some of the results of pitch roll and other such likes. Look up Panbo for their test.

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Old 29-05-2012, 13:44   #6
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Re: AP Steering to Wind Angles?

We just sailed from the Abacos to Beufort NC on our Pretorien, over 3.5 days. Most of this was sailed with the autopilot in wind mode. We sailed wind angles from 40 to 160 degrees. Conditions were mostly 6-8 foot seas, with larger in the gulf stream. We had winds from 12-24kts. The autopilot preformed very well. It would let us know when the wind angle changed more than 20 degrees from when it was set, so we could make adjustments accordingly. Our sailing included being double-reefed (we have only two) and moderate surfing at night. We never felt out of control, but it was a bit of a "Ride" at times.



We have

Simrad AC12
Simrad NSS7 chartplotter/autopilot controller
Maretron WS100 ultrasonic wind instrument
Octopus Hydraulic drive
Airmar H2183 (Right #?) compass

I would not be surprised if the combination of the good compass and wind instrument had a positive effect in the performance of the autopilot.

Chris
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Old 29-05-2012, 14:33   #7
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Re: AP Steering to Wind Angles?

I sailed most of the way to Tortola from Norfolk in wind vane mode. Worked great. On the Bay the nice thing about them when short handed is they will tack the boat while you play with the headsail sheets.
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Old 29-05-2012, 15:44   #8
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Re: AP Steering to Wind Angles?

It's the usual way I use my autopilot when sailing. Works great. Kudos to Raymarine.
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Old 29-05-2012, 15:57   #9
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Re: AP Steering to Wind Angles?

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Originally Posted by Dockhead View Post
It's the usual way I use my autopilot when sailing. Works great. Kudos to Raymarine.
+1

I have used it sailing downwind in 30 knots and 8 foot seas, and it tracked better than I could steer manually (my attention would sometimes wander, but the AP has no Attention Deficit Disorder ) .

I'm using a Raymarine Smartpilot S2G (with gyro) course computer.
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Old 29-05-2012, 16:49   #10
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Re: AP Steering to Wind Angles?

G'Day Greg,

FWIW, we don't have a vane on I-2, and I sure wish that we did.

But, one thing not yet mentioned: for boats that surf much, steering downwind to a set wind angle (whether a/p or windvane) can be dangerous. When you accelerate down the wave, the apparent wind goes rapidly forward. The a/p or vane turns to leeward to compensate. Then, when you reach the "bottom" of the wave face you slow rapidly and the apparent wind moves aft again and this can lead to an accidental gybe before the boat turns back on course. We've found that steering downwind to a set course is a lot more stable.

As it happens, when we first bought I-2 we contacted Windpilot about supplying a vane for her. The owner of that company provided the quotation, but advised strongly against fitting the vane for the above reason and so we didn't. For the majority of the time (that is, non surfing conditions) I'd be much happier with the windvane and wish that we'd gone ahead with it. Now they are so damn expensive (changes in the USD) and I keep putting it off!

Cheers,

Jim
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Old 29-05-2012, 18:23   #11
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Re: AP Steering to Wind Angles?

I use my AP ? wind vane setup offshore all the time. I will sail off the wind a little more than I would steer manually and decrease the AP sensitivity to avoid luffing in gusts. It steers better than me.
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