Autopilot backward

Roberto

Roberto

Well-Known Member
Joined
20 Jul 2001
Messages
5,856
Location
Lorient/Paris
sybrancaleone.blogspot.com
I have a ST6000 auto pilot, is there a way of letting it steer the boat *backwards* to a fixed course ? I went through the manual and have found nothing

I felt it would be nice when coming out of crowded anchorages: put in reverse gear at lowish rpm, the boat stabilises while on the bow one has the time to calmly stow anchor and chain, no problems in making tight turns or approaching too much to shallow bottoms, etc.

one steers forward, raise anchor, pilot in rear and off we go /forums/images/graemlins/smile.gif

?
 
How does the autopilot know which way you are going anyway? No reason in theory why it wouldn't steer going astern except that until you are underway at a reasonable speed it won't be able to work out whether it is on course. Your speed will need to be enough to give steerage and overcome wind/tide which doesn't sound like a good idea in reverse in an anchorage.

I've never done it so perhaps others know better.
 
The answer is the autopilot doesn't know which way you're going - it's set up for steering going forward. Going astern, if the boat starts to drift off course to starboard, the autopilot will apply left rudder, moving the boat further off course. Won't work!
 
yes that is what I thought /forums/images/graemlins/frown.gif

I was thinking maybe temporarily swapping positive and negative from the compass?
but then it should be a real failsafe method (if that ever exists) /forums/images/graemlins/ooo.gif

anyway, I think it would be a nice addition, especially when it is a bit windy: when I motor near the marina and need those 5/10 minutes to put fenders on, prepare mooring lines, put mainsail cover, wait for the ferry to come out of the port, etc, with the engine in forward it need quite a bit of power to keep the boat on course so one must really hurry, whereas in rear gear at idle the wind would do most of the work in keeping the boat stable and the pilot would simply steer it very lightly
 
<span style="color:red">Use a remote .. <span style="color:blue">Then you only have your self to blame if you <span style="color:purple">hit <span style="color:blue">something .. /forums/images/graemlins/cool.gif
 
Yep..full appreciate the problem and would love to hear how you resolve it. Just can't get the staff these days. Must be worth testing a few of the ideas suggested ...You are still in Lorient?
 
[ QUOTE ]
<span style="color:red">Use a remote .. <span style="color:blue">Then you only have your self to blame if you <span style="color:purple">hit <span style="color:blue">something .. /forums/images/graemlins/cool.gif

[/ QUOTE ]


hmmm, hitting someone while going in reverse... anyone for a one night colregs debate ? /forums/images/graemlins/cool.gif
 
What a dumb idea

If you want to know why this is a dumb idea, just let go of the wheel or tiller whilst going astern. The water flow past the rudder will force it onto full lock. Most autopilots will be completely incapable of coping with the forces involved, as they rely heavily on the usual tendency of the helm to self centre, which is essentially "fail safe."
 
[ QUOTE ]
I suppose you could build a switch into the circuit to reverse the sense ...

[/ QUOTE ]

It's already in the instructions, presumably to cater for the Southern hemisphere: dpuble-pressing of buttons for a specified time as I recall. And a very simlar operation turns the lighting on/off and yet another reduces the response bandwidth.

So if you saw some idiot coming out of Yarmouth at night barging around in circles . . . .

Been there!
 
Re: What a dumb idea

[ QUOTE ]
The water flow past the rudder will force it onto full lock. Most autopilots will be completely incapable of coping with the forces involved

[/ QUOTE ]


Is this a feature of the autopilots ? when forces are too big they go into full lock ?
shouldn't the fuse protect them from overload ?
 
Re: What a dumb idea

No it is is not a feature of the autopilot, it is a simple fact about going astern.
The autopilot only has so much power. On most systems the autopilot will switch itself off and sound an alarm if the forces on the rudder are too much for it. Mine is a Simrad Robertson, but I have no doubt that yours will do something similar. Going ahead, these forces are usually trying to centre the rudder, going astern the forces will push it over onto full lock.
(just what you always wanted when trying to back into a marina berth.)
 
Re: What a dumb idea

[ QUOTE ]
No it is is not a feature of the autopilot, it is a simple fact about going astern.
The autopilot only has so much power. On most systems the autopilot will switch itself off and sound an alarm if the forces on the rudder are too much for it. Mine is a Simrad Robertson, but I have no doubt that yours will do something similar. Going ahead, these forces are usually trying to centre the rudder, going astern the forces will push it over onto full lock.
(just what you always wanted when trying to back into a marina berth.)

[/ QUOTE ]

yes sure but IMHO it may be worth a try, I am not talking about going astern at 6kt, but put the engine in gentle reverse with the boat on course, perhaps putting the response speed at highest level... pilot corrections would hopefully be made very soon with the smallest deviations from the course, when forces on rudder are still manageable
 
Re: Why on earth would you ant to do it in the first place ??

I often felt it might be useful (copy from above) especially when it is a bit windy: when I motor near the marina and need those 5/10 minutes to put fenders on, prepare mooring lines, put mainsail cover, wait for the ferry to come out of the port, etc, with the engine in forward it need quite a bit of power to keep the boat on course so one must really hurry and change course, whereas in rear gear at idle the wind would do most of the work in keeping the boat stable and the pilot would simply steer it very lightly

/forums/images/graemlins/smile.gif
 
You must log in or register to reply here.

Share this page

Top