Auto pilot connection to plotter

[emnick]

Am I missimg something here.
I am going to fit an Easy AIS to the Raymarine C120. I have a seperate GPS for connecting additional NMEA listeners. Do most people interface the plotter with the auto pilot on a sailing boat. I can understand it on a Mobo following routes etc but I really cant see a time when I will let the boat follow a route or am I missing something???. Is there any reason why I cant use the auto pilot as a stand alone unit
Thanks for any advice

 

[flaming]

No reason you can't use it as a stand alone pilot if that's what you want to do.
However I quite like the ability to track to routes. For short tidally affected legs it saves the bother of working up a course to steer. Hardly traditional I know, and I can hear the intake of breath from the traditionalists now, but provided you sense check it there should be no problem.

 

[simonfraser]

saves the bother of sorting out a course to stear for, minor prob with sail boat is the wind you can link the autohelm up to a wind unit. works even better imo.

i set te course needed using the plotter, then steer the boat on the wind using the autohelm for the 'best' vmg.

keep a look out though !

 

[boatmike]

Good point! Everyone seems to interface everything because technology makes it possible. Personally I don't, especially the autopilot. With variable wind, tide, and leeway I think it's a waste of time. On a cross channel passage for instance I like to set a course which my PC based tidal planning software tells me is optimum for the speed I predict, look at the actual course it predicts over the ground and transfer waypoints at the point where tide turns to my chartplotter at the helm. It is unusual not to make corrections to the course steered by the AP though when underway as my speed and wind direction/strength may not be as predicted. In fact it would be rare if it was and sometimes the course cannot be steered at all and a "new" course needs to be calculated en route!
I suppose in the Med where there aren't tides to worry about it might be OK but I don't see the point otherwise really.

 

[Refueler]

If I had a later tillerpilot that could interface to my plotter - it would be the first connection after power I would make. I have a sailboat and would love to be able to do it.

I don't understand why anyone would be against it ? The tillerpilot will not track to next course before you acknowledge, the tillerpilot only mimics what you would do in keeping a course.
Some say only interface with wind ... great - so what do you do when under engine ?

 

[Robin]

Ours is linked to the plotter but very rarely used to drive the pilot except when we really need to stay on the ground track as for example following a tight channel with variable cross tides. An example would be to follow our preset route through Chenal Du Four between Ushant and NW France mainland in bad visibility because the tide rates and direction are constantly changing and rarely just from ahead or astern. Having the plotter/GPS tell the pilot how to keep on track then allows us to concentrate on the radar and visual watch. Be aware that the pilot will not turn onto a new course when a waypoint is reached without confirmation that this is OK by a button press. I will add that when we do use ours in this mode it is on routes that we have checked first in clear visibility and if necessary tweaked the waypoints to stay clear of nasties. As others have said you may find some of the headings required to stay on track might not suit the wind direction under sail, but in my example above and in fog I'd forgo that if needs be and run the motor when needed.

If you don't interface the pilot and GPS and run the pilot as a standalone you can still do it manually by changing heading to keep X-track error at zero.

One other reason for interfacing is that the pilot control head will also display any data being circulated from any other instruments so the pilot can display other information than might be set up to show on the plotter.

 

[pvb]

I haven't interfaced my C120 with the autopilot, and really haven't ever wanted to. If you decide to do it, remember that your C120 won't output NMEA data when it's set to receive AIS data. As a result, you'll need to run the autopilot on SeaTalk.

 

[flaming]

[ QUOTE ]
Good point! Everyone seems to interface everything because technology makes it possible. Personally I don't, especially the autopilot. With variable wind, tide, and leeway I think it's a waste of time. On a cross channel passage for instance I like to set a course which my PC based tidal planning software tells me is optimum for the speed I predict, look at the actual course it predicts over the ground and transfer waypoints at the point where tide turns to my chartplotter at the helm. It is unusual not to make corrections to the course steered by the AP though when underway as my speed and wind direction/strength may not be as predicted. In fact it would be rare if it was and sometimes the course cannot be steered at all and a "new" course needs to be calculated en route!
I suppose in the Med where there aren't tides to worry about it might be OK but I don't see the point otherwise really.

[/ QUOTE ]

I don't think anyone's suggesting it for a cross channel.

Where it does come into its own is following a relatively narrow channel with a cross tide, especially with few visual references.

In years gone by this was done with a good course to steer, but the good people at Raymarine etc have given us a new tool which does that job even better. Excellent, less time at the chart table, more in the cockpit!

 

[boatmike]

You make some good points Robin and I guess the advantages of interfacing do rely on how and where you sail. In particular though my own preference is for visual confirmation and monitoring but I have an enclosed wheel steered boat with a comfy seat and the chatplotter with 12" screen right in front of my nose so it's easy to see any deviation from intended course and correct by pushing a button on the AP control without getting up! If you have the CP below perhaps it makes more sense interfacing, but being a sailing dinosaur I dislike anything that detracts from manual decision making en route and get paranoid when electricery takes over to that extent!

 

[Refueler]

But in fact it doesn't do that much more than what you are doing manually - as it will not turn to new course until you accept the alarm and agree to turn. The advantage is that it keeps the xtrack error down while steering to a course to waypoint.

 

[boatmike]

I don't accept that it reduces error any more than seeing your course on the plotter, comparing it to the course required and making a manual adjustment. The accuracy of the course will be the same and limited only by the ability of your AP surely? However if you want to interface it go ahead, I have not said that it's wrong, just that I prefer not to, largely because most of the courses I steer don't follow a straight line over the ground because it's not the quickest route in a tideway.

 

[Refueler]

Each to their own and it's not intended as argumentative.

The plotter xtrack error will adjust the AP to a finer degree than you will. It's like comparing manual steering to automatic. Automatic will use less helm to maintain the course aiding fuel economy and also speed due to less rudder angles and deflections.
The plotter will do similar as it catches slightest xtrack that we as humans would ignore until xtrack is sufficient to prompt us to correct - we would also correct often a little too much. I say that as a manual corrector like you ! I cannot interface my autohelm, as the nmea sentences have an addition to the identifier since my old AH was made ... it cannot read it.

I agree that in tidal situations and with adequate searoom - it's often better not to keep tight to course line but to 'go with the flow'. But in tight situation it can be advantage as it reduces strain on the "skipper' by assisting - NOTE I say assisting to keep boat on track.
I would never let it take over my prime duty !

 

[hightech]

If you have a radar connected to the plotter, then a connection to the pilot is a must to give you stabilisation and radar overlay.

Interfacing the units together has far more advantages than not.

NB.does not really apply to the "all in one" tiller pilots.

 

[emnick]

Thanks for the posts, I have radar connected to the plotter but I was under the impression that I need a fast heading sensor to stabilize for MARPA not sure how connecting the AP will help here.