Heaving-to with autopilot

[Wrong]

Posted by Alby1714

"Wrong and Stu Jackson: I do not know what make is your ap but is probably not like mine. When my ap is in stand-by the rudder is free and the helmsman can steer by hand. The rudder is also free if I turn the ap off, so those are options I cannot use for heaving-to."

I do not see the problem... If the "rudder is free...and can be steer(ed)...by hand" when on standby or off, why can't you lash the helm to weather? Precisely how does this affect the autopilot if it's disengaged?

[colemj]

Originally Posted by Alby1714

Mark,
Presumably if I made the voltage of the external power supply manually variable, I could set the rudder to any desired angle within its range from hard over port to hard over starboard.

No, the clutch is an on/off thing. It doesn't variably move the rudder - it only locks the drive unit. You would set the rudder angle by hand and lock the clutch by applying 12V to the clutch wires. If you want to change rudder angle, you would depower the clutch, move the wheel by hand and repower the clutch.

You should, however make sure the clutch wires going to the computer are disconnected when you connect an external power source to them. This shouldn't be too difficult using a relay or switch to automatically disconnect one when the other is connected.

If you want to electrically control the rudder, then you would have to hook a reversible power supply to the drive's power wires. This doesn't make much sense to me and seems problematic.

Mark

[Alby1714]

Originally Posted by colemj

The OP's original concern was the stress on the steering system, which using the mechanical wind vane would not alleviate. He was wishing to put all the forces onto only the quadrant and AP drive/mount.

However, I think if the entire steering system can't handle the hove-to stresses, then it needs attention.

Mark

Mark,
Thanks for explaining in very clear terms the nature of my concern.

Please notice that, as I mentioned earlier on, I am worrying about what could happen in storm conditions, say above 40kn. In general terms the probability of a failure in any system increases with the number of components in that system, (and we all know that what is not there, is not going to break). Because the steering system is vital, if at all possible, I prefer to take any reasonable and easy-to-realize precaution.
Thanks again for your viable suggestion of the external power supply.

[Alby1714]

Originally Posted by colemj

No, the clutch is an on/off thing. It doesn't variably move the rudder - it only locks the drive unit. You would set the rudder angle by hand and lock the clutch by applying 12V to the clutch wires. If you want to change rudder angle, you would depower the clutch, move the wheel by hand and repower the clutch.

You should, however make sure the clutch wires going to the computer are disconnected when you connect an external power source to them. This shouldn't be too difficult using a relay or switch to automatically disconnect one when the other is connected.

If you want to electrically control the rudder, then you would have to hook a reversible power supply to the drive's power wires. This doesn't make much sense to me and seems problematic.

Mark

ok, understood.

[autumnbreeze27]

If you heave to and find your heading is 000 and the wind is out of the west, couldn't you set your AP to turn the boat to heading 300 and it would put the helm over to port, but the head will never come around because of the backwinded jib. Ok, so then you have the risk of a wind shift, but assuming you have a wind instrument connected to the AP, you could steer to wind using the same concept. Wait until the boat is settled and then set it to sail to wind, the current wind angle should be perfect. Maybe turn the sensitivity all the way down so it doesn't slam the rudder around.

Personally, I think lashing the wheel sounds more desirable. Using the AP, you could have a problem with the AP, or you could lose power. If your steering gives out, use the AP to steer as backup (assuming the quadrant didn't fail)

Another possibility--any way to rig and lash down the emergency tiller?

Hope ya never have to use any of this info

[Wrong]

This issue is one reason I cannot understand why sailors go to the expense of installing and then rely on autopilots for steering. Especially when a servopendulum wind steering system is on the boat.

Go figger...

[Alby1714]

Originally Posted by autumnbreeze27

If you heave to and find your heading is 000 and the wind is out of the west, couldn't you set your AP to turn the boat to heading 300 and it would put the helm over to port, but the head will never come around because of the backwinded jib. Ok, so then you have the risk of a wind shift, but assuming you have a wind instrument connected to the AP, you could steer to wind using the same concept. Wait until the boat is settled and then set it to sail to wind, the current wind angle should be perfect. Maybe turn the sensitivity all the way down so it doesn't slam the rudder around.

Personally, I think lashing the wheel sounds more desirable. Using the AP, you could have a problem with the AP, or you could lose power. If your steering gives out, use the AP to steer as backup (assuming the quadrant didn't fail)

Another possibility--any way to rig and lash down the emergency tiller?

Hope ya never have to use any of this info

Atumnbreeze,
thanks for your interesting remarks. I will start from your last one. If I could easily rig and lash my emergency tiller I would do that and would not bother to modify the ap !
My boat is a Hallberg-Rassy 36. It is an excellent boat but unfortunately it has the rather undesirable feature that the emergency tiller is not rigged on deck but it is rigged inside the stern cabin .
The issue of potentially having to steer the boat from inside the stern cabin is beyond the topic of our discussion here, however, also creating strong points to lash the tiller to, inside the cabin, is another significant issue that I would like to bypass by acting on the autopilot.

I have never tried to heave to with the autopilot in "steering mode" as you suggest, although I have thought of it. As you may have read in my earlier e-mails I am talking about storm conditions here, in "normal" conditions I do not hesitate to lash the wheel if I need to heave to. In storm conditions however I would not heave-to with the ap in "steering mode" running the risk to have the ap to act unpredictably and for example slamming the rudder and the rest of the steering system which is exactly the gear I am trying to protect.

All you are saying about potentially having a problem with the ap or lose power is true. My rationale for opting for protecting the steering gear and exposing to unknown levels of stress the ap is that onboard I have a second (spare) drive unit for the ap that I could use if the first failed. On the other hand I have only one steering system (one set of wires, one chain and no spares), maybe I should get some spares for those items as well !
I hope I answered your points.
Incidentally, the small electrical kit necessary to implement Mark's suggestion is already being made, I will report if anyone is interested how well or how bad it will perform. Cheers.

[Alby1714]

Originally Posted by Wrong

This issue is one reason I cannot understand why sailors go to the expense of installing and then rely on autopilots for steering. Especially when a servopendulum wind steering system is on the boat.

Go figger...

Wrong,
my own reply to your question is redundancy in the first place; additionally if one is motoring an ap is a long way better that a wind vane self steering gear and if one is motoring into the wind the ap is the only answer.
Cheers.

[colemj]

Originally Posted by autumnbreeze27

If you heave to and find your heading is 000 and the wind is out of the west, couldn't you set your AP to turn the boat to heading 300 and it would put the helm over to port, but the head will never come around because of the backwinded jib.

This won't work because the AP will try to turn the boat until it finally moves the rudder to the stops and then error out and go into standby with a warning beep and message.

I don't know how the OP's AP in particular will handle this, but every autopilot I have ever used responds like I mention.

Mark

[Stu Jackson]

Alby, could this be an opportunity to actually use the aft cabin emergency steering "station?"

Heave to using the wheel, then lash down the quadrant using the emergency gear. Done.

I think most of us are trying to discourage the use of the ap to do the quadrant-jamming, since while you're "avoiding" the use of the rest of the steering components, you're introducing yet another point of failure by trying to use the ap.

[colemj]

Originally Posted by Wrong

This issue is one reason I cannot understand why sailors go to the expense of installing and then rely on autopilots for steering. Especially when a servopendulum wind steering system is on the boat.

Go figger...

I understood from the OP's first post that he already has an AP on board and that he doesn't want to put stress on the steering system when hove-to - which is unavoidable with a wind vane.

As to your point in general, most AP kits are less expensive than wind vanes and their mounts - particularly for smaller boats. Additionally, wind vanes work very poorly, or do not work at all for many types and sizes of boats. And that is leaving alone the whole motoring and very light wind thing...

Mark

[colemj]

Originally Posted by Stu Jackson

I think most of us are trying to discourage the use of the ap to do the quadrant-jamming, since while you're "avoiding" the use of the rest of the steering components, you're introducing yet another point of failure by trying to use the ap.

Technically, there should be no problem doing this - particularly with a hydraulic ram, but even so with a mechanical one. The only thing the drive actually does is hold the rudder tightly in one position. It is only the course computer that makes it move around at all.

However, a well-found steering system should have no problem holding a boat hove-to.

Mark

[autumnbreeze27]

Make sure your hydraulic ram mount is weaker than your quadrant, so if something breaks it's on your AP.

If you lash the helm isn't there some play in the lashing and steering cables to absorb some "stretch"? Versus a locked up AP which will transmit any shock loads directly to the mounts/rudder? I guess if the AP will handle that load... but I wouldn't want to try and swap out an AP hydraulic ram in 40kts of wind and a failed steering condition!

I get what you're saying about the error out condition, I didn't get consider that.

Our emergency tiller is in the aft cabin as well. I figure if push comes to shove I'll be rigging a block and tackle to steer the boat with (putting lots of ugly holes in the teak furniture in the process)

[Alby1714]

Originally Posted by Stu Jackson

Alby, could this be an opportunity to actually use the aft cabin emergency steering "station?"

Heave to using the wheel, then lash down the quadrant using the emergency gear. Done.

I think most of us are trying to discourage the use of the ap to do the quadrant-jamming, since while you're "avoiding" the use of the rest of the steering components, you're introducing yet another point of failure by trying to use the ap.

Stu Jackson,
at the moment I do not have any good and obvious attachment points to lash down the emergency tiller inside the aft cabin.
If I had to do that in an emergency rush I would probably massacre the rather nice teak work. This does not mean though that I will not try, as a future project, to see if I can identify or install sturdy attachment points inside the cabin to lash properly and securely the emergency tiller without damaging the teak work.

As for the quadrant-jamming done with the ap I think that I am introducing a different point of potential failure while I remove other potential points of failure. As implementing the ap modification is easy and inexpensive, I will do it.
While I have the feeling that heaving-to in storm conditions using the ap option carries a smaller probability of failure than by lashing the wheel, I am not at all certain that that is actually the case. However once the modification will be in place I will be able to experiment with it in moderate conditions and try to gain some insight on which course of action is actually better to heave to in storm conditions.

[Alby1714]

Originally Posted by autumnbreeze27

Make sure your hydraulic ram mount is weaker than your quadrant, so if something breaks it's on your AP.

If you lash the helm isn't there some play in the lashing and steering cables to absorb some "stretch"? Versus a locked up AP which will transmit any shock loads directly to the mounts/rudder? I guess if the AP will handle that load... but I wouldn't want to try and swap out an AP hydraulic ram in 40kts of wind and a failed steering condition!

I get what you're saying about the error out condition, I didn't get consider that.

Our emergency tiller is in the aft cabin as well. I figure if push comes to shove I'll be rigging a block and tackle to steer the boat with (putting lots of ugly holes in the teak furniture in the process)

Atumnbreeze,
your questions are correct but I do not have an answer (yet). As I said to Stu-Jackson above, the modification of the ap is easy and inexpensive so I will try and experiment with it in moderate conditions to see how it performs.