How Strong an Autopilot do I Need?

[colemj]

Originally Posted by zeehag

my boat is light at 28000 pounds dislplacement--spozed to be 34000.

Where did the extra weight go? Those boats are not known for coming in under design weight.

Mark

[colemj]

Originally Posted by Journeyman

Hi Mark,

The unit was installed by Raymarine certified installers including a rudder position indicator. The leg where I experienced poor performance was about 3.5 hours, with the wind and chop gradually building over the first 1.5 hours. So plenty of time for it to learn the conditions.

The point of sail was maybe 30-40 degrees to the wave face, with wind gusting to 21-22 kts true, and sustained 19-20kts, at about 50-60 degrees AWA, one mainsail reef and a 140% roller furled to maybe 110%. So not the best airfoils and probably could have reefed more. Boat is 37 LOA, 32 LWL, 11.5 beam, 20,000 lbs, with 250' of chain in the bow.

The course was held most of the time, but after a lot of wheel action with the boat heading up in a gust and cresting a wave, it would be slow to correct as the bow then fell off to leeward some 30-40 degrees over about 4 seconds, and then it would correct back up to course, and do ok until it happened again.

I would take it off auto occasionally to gauge the weather helm by feel, and it did not feel really excessive for these conditions. Also, while hand steering I was able to busily correct ahead of time before the bow fell off too much, and keep from veering to leeward like the pilot was doing.

I only have about 400 miles on the new Evo so far and except for this one leg where I had high expectations, the conditions have been moderate at 10-15kts, mostly motor sailing, and easy for the Wheelpilot or Evo to handle.

I do like the relative silence of the Evo compared to the squeaky belt driven Wheelpilot, and I share your expectations that it will prove robust over time. But then so has my Wheelpilot.

I will discuss this with my installers and Raymarine. And read comments and advice here.

Thanks,
Journeyman

Since you left the wheelpilot in place, did you get a chance to compare them in the same conditions?

I suspect something is wrong with your installation or the unit itself. Those sailing conditions are rather mild for your boat, and autopilots with rate compensation should have easily kept you dead on course with no yawing at all.

Mark

[Panope]

Greetings Journeyman,

Do you feel that the problem with your new system was a 'physical' problem (lacked the power to move the helm quick enough), or was it a 'mental' problem (not smart enough to move the helm in the correct way)?

Steve

[colemj]

I just read the Evo installation manual and had some thoughts. Check the response setting to see if it is appropriate. Also check the boat type for the same.

What is the deviation number on the control head?

If the compass lock is on, turn it off and go sailing again. It is possible that the compass linearized itself next to a strong field (like a steel boat) and needs to relinearize itself. It appears that it will do so automatically. If you want to force the issue, simply restart the compass and then do a 360* turn at 3-5kts.

Mark

[Journeyman]

Originally Posted by Panope

Greetings Journeyman,

Do you feel that the problem with your new system was a 'physical' problem (lacked the power to move the helm quick enough), or was it a 'mental' problem (not smart enough to move the helm in the correct way)?

Steve

Definitely feel its "mental" problem. It just seemed to be way behind the curve in timely correction as the bow fell off. It wasn't doing anything proactively to anticipate and correct the periodic yawing.

[Journeyman]

Originally Posted by colemj

I just read the Evo installation manual and had some thoughts. Check the response setting to see if it is appropriate. Also check the boat type for the same.

What is the deviation number on the control head?

If the compass lock is on, turn it off and go sailing again. It is possible that the compass linearized itself next to a strong field (like a steel boat) and needs to relinearize itself. It appears that it will do so automatically. If you want to force the issue, simply restart the compass and then do a 360* turn at 3-5kts.

Mark

I will do this next week when back at the boat. Hopefully, along side the installation techs if I can get them back onboard. I was not present as they did the install nor have I asked them about their system setup choices. So far I have just been the test pilot.

Thanks for priming the pump with these questions, I will read that install manual myself ahead of the meeting with the techs.

Anyone reading this should not make any judgments about the Raymarine Evo quality from my experience thus far since the set up may not be dialed in yet. We are having debug issues with the new e7d MFD and I70 related to depth sounder and AIS display that cropped up in the 400 mile shake down. But they are slowly being resolved and seems to be system setup related. Hopefully all will be resolved before the next shake down sail in a few weeks from San Diego to Puerto Vallarta.

[rebel heart]

Originally Posted by colemj

For motoring or light air, that wheel pilot is just fine on most boats. I bet it gives up the ship well before your windvane during tough sea/wind conditions. And well before a good below deck pilot.

Mark

That's all I want it to do; easy conditions. The vane handles the bigger stuff. I think I'm actually going to switch to a tiller pilot (on the stubby tiller that the hydrovane has). Cheap backup, can set it to a compass heading, no wires other than 12v in, Bob's your uncle.

[rebel heart]

Originally Posted by Journeyman

Anyone reading this should not make any judgments about the Raymarine Evo quality from my experience thus far since the set up may not be dialed in yet. We are having debug issues with the new e7d MFD and I70 related to depth sounder and AIS display that cropped up in the 400 mile shake down. But they are slowly being resolved and seems to be system setup related. Hopefully all will be resolved before the next shake down sail in a few weeks from San Diego to Puerto Vallarta.

Not to play arm chair admiral but hopefully you guys are waiting ~30 days or so. It's still peak cyclone season and the water temps are still plenty hot for tracking big storms up the peninsula. Not a lot of places to hide along the Pacific side of Baja.

Given any thought to where you're going in Banderas Bay? La Cruz so far is my favorite place .

[brianb00]

This sounds like a lack of feedback from the rate gyros, which is usually part of the "gain/response" setting. What was the chop like ? Size, or rather did the chop cause a lot of pitch and roll ? The compass compensation depends on the rate gyro's to correct compass error due to the dynamics of yaw, pitch, and roll as the compass sensors have to be heavily filtered and result in a slow compass until gyro feedback is fused with the other sensor data. So pitch and/or roll could cause compass error without proper feedback settings. An interesting experiment, sail through a ship wake at right angles and see what the rudder action is. If you see a lot of waggle likely cranking the response/gain settings up would help. Try the same thing parallel to a wake (induced roll) and see how the rudder responds. I would assume with a new design like the EVO you could tune out these types of induced errors. Is there a setting that switches on adaptive mode versus a fixed response mode ?

[beauris]

Originally Posted by ullar

There hasn't been any mentioning of NKE pilots here. They are expensive but supposedly the best pilots available.

i use an NKE on my 41 footer ( sun legend) and i am more than happy with it...it s not terribly user friendly though but extremely reliable and precise