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Old 27-10-2011, 17:47   #16
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Re: Why Integrate the Autopilot ?

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Originally Posted by colemj View Post
Why are some of you assuming because the autopilot is getting course instructions from the GPS that no one is watching and able to respond or tweak the pilot?
Well Mark, its my views. I would like to hear how integrating helps you, and I will make up my own mind, just as you have done.



How is integration different than just setting the autopilot to a compass course and abandoning the helm/watch?
I plot my course, backtrack and know it is a safe route to follow. I have backup plans from the old GPS unit to paper charts (mostly bellingham photocopies) I would not say I "abandon" the helm. I sit in the cockpit.


Integration has nothing to do with seamanship at all. And a mindset of trust of electronics also has nothing to do with seamanship any more than a mindset of trust in your rigging.
The comment about seamanship and trust. Smart plotters guide a track based on parameters. I have what was the latest and greatest Garmin and this feature has gotten it wrong on occasion. I guess the "trust" comment should have said that I am aware of the limitations of the equipment.

I do think this has a lot to do with good seamanship

Mark


We may agree to differ, but I appreciate your views.
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Old 27-10-2011, 18:08   #17
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No one on watch, in a traffic/hazard area, is poor seamanship.

Trusting one piece of equipment, with no backup, is poor seamanship.

Prepare for the worst, have a backup to the backup!!!!
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Old 27-10-2011, 18:08   #18
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Re: Why Integrate the Autopilot ?

Hell, I just sailed from Benicia to outside the Golden Gate with a stop at Angel Island, all using waypoints on our chartplotter and the autopilot. I have a crew, my better half, but essentially sail single handed, the pressure is really off sailing to a waypoint. Of course you have to keep a lookout, but you don't have to steer. Course changes are easy with the "jog" function on the AP. With the Raymarine/Navionics charts I have lots of options, including overlaying radar on the screen. So why not?
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Old 27-10-2011, 18:47   #19
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Re: Why Integrate the Autopilot ?

I agree with Mark, just because the Pilot is taking instructions from another source doesn’t mean there’s no-one on watch. Having no-one on watch is the concerning (or stupid) habit – no mater how ‘quick’ it was…

We are integrated and I wouldn’t have it any other way. If you set a bearing course on the Auto Pilot it will essentially keep the boat pointing (facing) in a the same direction – If you set the Pilot to ‘Track’ to a point on the plotter it will keep the boat travelling in the same direction, I’ve seen these two (Course Over Ground v Heading) vary by more than 30 degrees at times! It’s a very different work load level.


It was fiddly to get devices from other brands all happy together but once done has been perfectly reliable.
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Old 27-10-2011, 23:16   #20
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Re: Why Integrate the Autopilot ?

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Originally Posted by Eleebana View Post
The major disadvantage seems to me that one component failure may mean that you lose the functionality of every component in the system.

Can anyone help me with one advantage of having the autopilot integrated?
Firstly, you can typically wire the autopilot so that if any instrument goes down, the autopilot will still work independently. This is typically achieved by having one dedicated signal circuit for autopilot and a separate circuit for the boat instruments. Course computers will typically have two terminals to allow this.

Two big advantages of an integrated system is that (a) You can tell the autopilot to steer a course relative to the wind and (b) you can tell the autopilot to steer a course to a waypoint. Both of these are very useful features.

Whether you chose to utilise these features is up to you. I personally don't see any reason not to at least install the system so that you have this functionality available...even if you don't use it initially.
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Old 28-10-2011, 00:35   #21
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Re: Why Integrate the Autopilot ?

I use the wind angle steering feature a lot when close to the wind and when reaching in light air--I find that following the wind shifts and puffs adds about half a knot to my average boatspeed under autopilot.

I have not interfaced the autopilotpilot to follow waypoints. When I am sailing on a compass heading, I use the GPS Course Over Ground and Bearing to Waypoint readouts to adjust the autopilot heading. Part of being on watch is to keep track of the COG and BTW and adjusting course if necessary.

I also believe that following waypoints in congested areas is a good way to generate collisions or close calls. My course adjustments are not as efficient or accurate as the automatic waypoint following systems, so there is more crosstrack error in my course. If you have a cross track error of 0.01 miles or less, that means you will come within 50 feet of everyone else who has a cross track error of 0.01 miles and is traveling between the same waypoints.

Bazzer, you must have been motoring, not sailing, if you could let the autopilot follow waypoints from Benecia to the Golden Gate. That course involves several tacks in the prevailing winds, and I would have been using the wind angle feature most of the way.
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Old 28-10-2011, 00:42   #22
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Re: Why Integrate the Autopilot ?

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I use the wind angle steering feature a lot when close to the wind and when reaching in light air--I find that following the wind shifts and puffs adds about half a knot to my average boatspeed under autopilot.

I have not interfaced the autopilotpilot to follow waypoints. When I am sailing on a compass heading, I use the GPS Course Over Ground and Bearing to Waypoint readouts to adjust the autopilot heading. Part of being on watch is to keep track of the COG and BTW and adjusting course if necessary.

I also believe that following waypoints in congested areas is a good way to generate collisions or close calls. My course adjustments are not as efficient or accurate as the automatic waypoint following systems, so there is more crosstrack error in my course. If you have a cross track error of 0.01 miles or less, that means you will come within 50 feet of everyone else who has a cross track error of 0.01 miles and is traveling between the same waypoints.

Bazzer, you must have been motoring, not sailing, if you could let the autopilot follow waypoints from Benecia to the Golden Gate. That course involves several tacks in the prevailing winds, and I would have been using the wind angle feature most of the way.

Don, being more 'edumacated' than I, is saying the bones of my arguement.

Thanks Don, I agree with you!
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Old 28-10-2011, 00:52   #23
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Re: Why Integrate the Autopilot ?

Integration reduces the workload when it is beneficial to do so. Because you have it does not mean you are always obliged to use it nor it always has to be turned on. All it does is give you more options which is a good thing.

I use it mostly for running routes and for doing radar overlays on charts.
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Old 28-10-2011, 01:00   #24
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Re: Why integrate the autopilot?

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You're right of course - not a real compass but a calculated compass course from the GPS if the boat's moving.

You are also right that the integration of chart plotter and autopilot could adjust for cross track error from current -- if you are lucky enough to get them working. But it gives me the shivers that some boat coming at me is in command of an electronic "Captain Ron".

Carl
Most likely reason your GPS course disagrees with your magnetic heading is cross-current or leeway. Integrating will allow the autopilot to correct for these automatically.

As for the "shivers" - don't you ever use an autopilot? On A/P you still keep a lookout right? Just as you'd do when the pilot is being "steered" by the GPS.
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Old 28-10-2011, 03:26   #25
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Re: Why Integrate the Autopilot ?

As others have said:

1. Setting the autopilot to a certain angle to the wind is terrific when sailing. That's the way I generally use the pilot when the wind is ahead of the beam, or if I'm close to a dead run. It's much better and more natural than sailing a given heading because the course will be changed if necessary to sail to whatever sail trim you have. If you sail a constant heading, your sail trim will be compromised in wind shifts. I would rather have the sail trim constant by default, and change course TOGETHER WITH SAIL TRIM, in case a wind shift puts me off course. This does not apply on a reach, especially a broad reach, where a few degrees of wind shift will not require a course change to maintain sail trim.

2. Track mode is useful when motoring. It holds your boat on a certain line, eliminating XTE.

Track mode has some important limitations. For one thing, I would never use it while sailing. Because in track mode, the pilot will steer the boat even quite aggressively, which can result in changing the point of sail without your permission, which could cause an unintentional jibe or other problems.

I would also never use track mode as a substitute for a proper tidal vector calculation, in case of a longer passage. You will motor a much longer trip as you crab along the rhumb line. Track mode is useful, however, for a shortish motoring trip with cross currents, where you want to arrive at a certain waypoint along a certain line, especially, when you want to follow that line to avoid some hazards.

But if you keep these limitations in mind, these functions are really valuable. So an integrated autopilot is, in general, a great thing IMHO.
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Old 28-10-2011, 05:06   #26
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Re: Why Integrate the Autopilot ?

Seems to me some (most) of the agruements aganist using the Track mode would apply pretty to using an autopilot at all.

None of the agruements on either side can replace the fact that you have to know when you should/shouldn't use your autopilot to start with.
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Old 28-10-2011, 06:25   #27
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Re: Why Integrate the Autopilot ?

We have B&G instruments, Furuno GPS and Radar, and Raymarine Course Computer, Compass and Autopilot. Everything is linked and totally integrated.

We do not use the track mode, even though we could
We do not use the wind mode, even though we could

Advantages that I like:
  1. Raymarine control head will digitally display all sorts of information such as depth, while our B&G instruments are analog.
  2. Waypoints are displayed on the Furuno radar
  3. Lat/Lon of the our boat and of cursor is displayed on the radar as well as heading (good info to have when hailing a radar target using VHF)
  4. Navigation software can compute drift when encountering current
  5. Navigation software can compute collision information on AIS targets

Advantages that we absolutely need:
  1. None

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Old 28-10-2011, 06:51   #28
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Re: Why Integrate the Autopilot ?

Radar overlay is a great feature. It shows when the maps are wrong.
Steering to a wind angle is of some us as is sterring to a waypoint.

Be careful if you have a route programmed in however. The autopilot can order a large course change (to the new waypoint) not so good if there is another boat in way.
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Old 28-10-2011, 06:59   #29
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Re: Why Integrate the Autopilot ?

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Originally Posted by Don Lucas View Post
Seems to me some (most) of the agruements aganist using the Track mode would apply pretty to using an autopilot at all.

None of the agruements on either side can replace the fact that you have to know when you should/shouldn't use your autopilot to start with.
I would not agree with this. In its basic mode, your autopilot will maintain a constant heading. Its mission in life is to steer the boat so that the bow is pointed in the same compass direction all the time. This is a good and useful mode, and you can sail in this mode in most conditions without any big risks. If the wind shifts, your sail trim will require correction. If there is a big wind shift, you could have an accidential jibe or other problems, but unless you're sailing quite close to a dead run, this is usually not a big risk.

Track mode lets the pilot steer the boat however it likes -- and on different headings -- in order to get onto the rhumb line and stay there. If you get swept off the rhumb line by a current, then the pilot will turn the boat and steer you in what might be an altogether different direction, in order to get you back on the rhumb line. Then it will turn back towards your waypoint and fiddle until COG and bearing to waypoint are the same. I have seen course changes of 30 and 40 degrees in track mode, as a result of this. In my opinion, this mode is entirely inappropriate for sailing, for that reasons.

You might not notice it if you are not sailing with big tidal currents (like where I sail), but if you are not sailing with big tidal currents, then you don't really need track mode anyway. You can use the basic heading mode, and adjust the given heading until COG equals bearing to waypoint, and you're set. Leeway is compensated. If leeway changes or the wind shifts, you will have to make adjustments. That's called "sailing".
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Old 28-10-2011, 07:02   #30
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Re: Why Integrate the Autopilot ?

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Originally Posted by noelex 77 View Post
Radar overlay is a great feature. It shows when the maps are wrong.
Steering to a wind angle is of some us as is sterring to a waypoint.

Be careful if you have a route programmed in however. The autopilot can order a large course change (to the new waypoint) not so good if there is another boat in way.
+1

Route-following mode, like track mode, is no good when you're sailing, since the pilot cannot re-trim your sails when it makes a big course change.

And when you're motoring, this mode also requires care for the reason mentioned by Noelex.
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