The Offshore Voyaging Reference Site

Chart Plotters And Autopilots, Never The Twain Should Meet


On Morgan’s Cloud we don’t hand steer much: approaching and leaving a wharf, anchoring and hauling the anchor, transiting an intricate channel, or in the presence of a lot of other boat traffic; that’s about it. We find that by using our autopilot we are left with more time and focus to navigate, keep a good lookout, and sail the boat. We also find that having a plotter has the same benefits.

But we don’t have the two electronic wonders interfaced to allow the plotter to instruct the autopilot on what course it should steer; we do that manually. Here’s why:

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There is no electronic or electro-mechanic technology that frees one from the responsibilities of command.

It is entirely possible to do irresponsible things with and without technology.

Therefore, interfacing competently designed, and manufactured equipment is no more or less risky—provided—one adjusts one’s command behaviors to the situation.

We use our interfaced system as a an extra, but not able-bodied, hand. We don’t treat the autopilot as officer of the deck, that is us.

We are, however, routinely nearly rundown by power and sail boats that code in a string of way-points and then go off to do who knows what perhaps with the presumption god is their pilot.

If there is a problem with any of these technologies it stems from the enabling of the in-able. A competent sailor should be able to interface with confidence and not to when conditions make it inappropriate.

David Nutt

On Danza we do have our GPS and autopilot linked and it has worked well for us in the last 50,000 miles of sailing. Like John and Phyllis we let the autopilot do 90% of the steering but we cold and shivering humans do 100% of the watch standing. This includes monitoring the track on the computer screen, the heading, the course steered and all the little bits and pieces of data obtained from this and everything else that consumes life at sea. Assumption is the mother of all screw-ups.

Robert in Norway

I have never had either a plotter or a pilot on any of my boats and never will. Paper charts and a Monitor vane cover all my needs and are fail proof. These boxes are expensive toys and dangerous when used by newbies. The pilot is an especially unnecessary bit of kit and having it onboard implies large batteries, charging systems and complexities involving the steering of the boat. If your boat is motoring in a calm, some one should be on the helm. The expense of of these toys does not help to make cruising “attainable”.

Scott Kuhner

Robert, did you know that you can set up your Monitor so that a small tiller pilot like the Raymarine 1000 will drive the wind vane? We use this method when we are sailing along a coast and want to steer a compass course, not a wind course.

Victor Raymond

As an aircraft pilot flying single pilot, we almost have to have the autopilot on and our navigation system driving the AP. They don’t call them Flight Management Systems for nothing. But there is a fairly large red button on the yoke of every modern aircraft that is FAA required to disconnect the AP just in case.
Boats on the other hand are very slow moving vessels for the most part. I agree with you and have never felt the need or the comfort in having the AP steered by the chart plotter route. In addition I have multiple redundancy with electronic charts available on my iPad, Garmin 496 and sometimes my trusty old MacBook. I have found different charts have slightly different information and I can compare them with what the eyes are seeing. While I do think having and using an AP is like having another trusted and faithful crew member, I do think having and using a wind vane system is a good idea too. It is on my list for the next boat.

Scott Kuhner

Great article. Thought you would laugh at a recent incident we experienced re chart plotters.

Tamure is at a dock in Jupiter Fl; but, we recently drove to Ft Lauderdale to have dinner with Steve and Karen James (whose boat is in the Med), David Bridges (who has sailed his Valiant 40, Blue Yonder across the Pacific) and his girl friend Marty, and Pam Wall, who has also sailed around the world with her late husband and their kids. While we were at the dinner table, Steve mentioned something about a new chart plotter and suggested I get one. I said that I don’t use one and don’t need it. “But”, he said, “The one I am talking about is only $600 and that includes all the charts of the US east coast.” I said, “Steve, we have sailed around the world twice, once with only a sextant, and the second time with a Sat Nav that would give me a position once every six hours or so. I am very vigilant in my navigation and besides, there have been more cruisers who have gone aground using a chart plotter than in the days when there was only the sextant. I do not need one!” Steve then came back with, “Scott, you should have one because they are very useful especially in situations where visibility is limited and where you aren’t sure where to go.” I said firmly, “Steve, I don’t want one! I am a very competent navigator and I don’t need one!” With that David reached into his pocket and pulled out his I-phone. He pushed a couple of buttons and showed it to Steve, who immediately broke out laughing. Then he pointed the I-phone at me and there was a picture David had taken of Tow Boat US pulling us off the sand bar at the entrance to Adams Creek. Touché!!

Steve Dashew

Howdy John and Phyllis:
We are back in Az and just read and agree with your piece on plotters and pilots. However, there are two situations where having the autopilot follow a track could be helpful. One is in an MOB situation. The other is if you have worked your way through an intricate channel and need to exit in less than ideal visibility, say an atoll in the S Pacific. That said, we do not have ours connected, but have thought about it because of these two scenarios.
After five days in the house I am ready to return to the boat!
Regards – Steve Dashew


John, you might want to look a little deeper at this. Five times and places on our last coastal US trip, we had the GPS track crossing either over or through unpassable areas (such as docks and bridges). We carry a GPS constellation and signal health monitor in our equipment suite and there were no performance issues with the constellation. [It uses statistical process control to detect and report worrisome position dilution and timing issues/trends.]

I was about to talk to the digital chart provider when I decided to download and print NOS charts for the area to see what was what.

In four of the five cases, the NOS Charts were wrong.

In two of the four, the docks were mislocated on the NOS chart by 10-12 meters— this was checked by comparing satellite photo measurements with chart measurements (both absolute and relative in case scaling was an issue).

In one of the four, the State did not build the bridge where it received federal approval to build the bridge and the NOS position was based on the federal approval drawings. Not only was the bridge deck 40 meters out of position, so were the approach ramps, etc for a mile either side of the channel. The mis-location was obvious on radar.

Finally the fourth spot was between Beaufort Inlet and Beaufort. The recorded trace from our depth finder showed us in more water than we needed and much less water than a spring tide lower low offered according to the chart. We altered course to the west to get out of the cresting swell this depth anomaly caused.

So let’s compare four piloting cases.

One, I’m electronics free and hand or windvane following a compass course laid in by plotting on a paper chart. The depth in Beaufort won’t be right.

Two, I have a full suite of electronics, not connected to one another, and I am hand/vane steering to a course laid in from a paper chart (ok, it’s null difference).

Three, I have a full suite, they are interfaced and auto steering to a compass course—same result.

Four, I have a full suite, they are interfaced, and I am auto-sailing to a waypoint on a digital chart that accurately represents an incorrect paper chart—same result.

While I very much respect the views presented here, as I noted in my first comment, the issue here seems to me to be about the inherent risks of sailing and the level of mental involvement on the part of the crew. If interfacing causes one to go brain dead, I would suggest avoiding it. If interfacing reduces fatigue and allows one to expand and extend one’s situation awareness as a result, I would recommend it.

We interface our equipment, and we allow the AP to use waypoint positions when it is navigationally appropriate, we don’t when it isn’t. We use course and heading inputs when waypoints aren’t appropriate. To us, this seems better than “never” and “always”—two answers my teachers often suggested would not improve my grades.


Aha, indeed it was. And as I said, I respect other’s choices, but having been rundown by a single hander who abjured integrated electronics, and was asleep from fatigue when he hit us, I remain convinced we are talking flavors of risk here.

Dick T M/V Julia Bryant

Right on- the non-interconnection of AP and Plotter. My personal technique (or lack of technique) is to slavishly use the course projection line on my Raymarine E Series in coastwise navigation. You can simply set the boat’s courseline projected to your next Waypoint, engage the AP but don’t interconnect. Granted this is a 12 Knot motorboat cruising where crosstrack error etc is less critical. Since there are two projections – one compass and one actual, you can soon figure out what’s happening crosstrack-wise. I have no idea whether most chartplotters can enable course projection lines, but would think so. Re: a previous comment on $ 600 backup plotters, my current one (for next season anyway) is my Droid X Motorola device with Navionics Eastcoast charts loaded for I think 13 bucks. Same would go for the IPhone. Of course this supposes you’re in range of Verizon’s 3G signal. I met recently an offshore fisherman at the New Bedford MA Verizon store and I asked him what sort of range he got with his cellphone. He said routinely when returning from Georges Bank, 40 miles out he climbs the radar mast and gets cell service to New Bedford.


interesting comments…many are along the lines of the radar topic of a few months back (my comment then was that radar tends to suppress our natural nautical instincts that we have worked so diligently to cultivate so i purposely do without it)…far be it from me to take issue with steve dashew; however, in all my many thousands of hours waterborne (still not in steve’s league) including blue water passaging, i have never even been close to any mob situation and my enounters with limited visibility are nearly as rare as i have a tendency to stay put if this is a threat….still steve’s opinions are extremely valuable…always happy to glean from his knowledge and skills….richard based in tampa bay…cavu’s skipper

Bob Tetrault

Hi John, Phyllis, right on! No interface on anything I own. Too easy to leave the watch for something unrelated to Navigation or safety. The only proper course change is a manual one. When I hear of others practicing unsafe navigation I wonder how long before we bow to rules and regulations aimed at keeping us from running into each other and the ground? My navigation instructor would roll over in his grave if he thought I adopted such practices. Bob Tetrault MMA 73D Retired merchant marine deck officer. S/V Sea Return

Steve Yoder

The pilot and plotter are not integrated on Sempre Sabado either. I just don’t like the idea. Another small advantage, besides all of those already listed is that, when I’m laying out a course prior to a trip, I set up waypoints where they look like they should be on the chart. However, when I get out in the real world, I often save some time when changing course by “rounding out” the turns instead of sailing all the way to my waypoint and then making an abrupt course change when reaching the actual waypoint that I plotted. This “rounding” could take another 4 or 5 waypoints per course change if I actually plotted the course that way. These adjustments are easy to make when the pilot is just doing what I tell it to rather than what the plotter is telling it to.

Marc Dacey

Sometimes an older post here will be revealed through a fresh comment made on it, and that once again illustrates for me how parallel our thinking is.

This is a screed I wrote somewhat critical of “integration” back in 2011:

I can’t say things have improved much, nor are people warming to my points of view.

Kim Graven-Nielsen

Hi John,
I need your advice, regarding a 2012 Furuno installation. I am selling my Hallberg 48 and have recently acquired a Hallberg 54. The 48 have Raymarine in all aspects and the 54 have a Furuno system from 2012. I have sailed the 48 from Europe to New Zealand with the Raymarine equipment and I am going to repeat the journey with the 54.The Furuno system have no fault except slow and tideus and hard to get serviced, it seems?
Would you replace the Furuno system and if so with what other brand?

Best Kim Graven


Hi John,
Have you looked at ‘Oscar,’ a new collision avoidance system recently described in Cruising World ( Oscar uses visible and infrared sensors to detect obstacles like partially submerged containers. I wonder why radar and forward-looking sonar are not in the sensor suite. But I am asking about it here because (I didn’t find a ‘collision avoidance’ article in your website, and) Oscar includes the capability of automatically steering the boat away from detected obstacles (with caveats): “some Oscar systems can autonomously control the boat’s autopilot to change course (see below)…” That is not a capability I’d want to use for reasons described in the above article.