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Old 23-04-2016, 02:11   #181
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Re: Raymarine St4000 with Trim Tab Problem

^^ I am with you Alan, I think it would work, and a multimeter would quickly figure out for sure but the risk is damaging or destroying one or both autohelms if its done wrong, or vibrates loose during the trip.

Id try it, but I am that kind of person that loves to tinker...

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Old 23-04-2016, 02:27   #182
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Re: Raymarine St4000 with Trim Tab Problem

RC, you have a good forcast. The mizzen is the tool you need to get the old girl steering herself. You will figure it out, or you wont, but basically sheet it in to steer into the wind, ease it to bear away downwind.

Motoring in a light headwind I would drop everthing except the mizzen then play with the sheet and rudder until she holds a course.

Use the old autopilot as a offcourse alarm so you can doze in the cockpit in marginal conditions.

Drop (or reef)the mizzen in strong beam winds and sheet the headsail in tighter than it should be. Play the main (and mizzen if its up) to get the course close.

Once the wind goes aft of the beam thats where life gets interesting. Ive only sailed one boat that would reliably hold a course downwind with just a lashed helm, that was a sistership to Suhali that I delivered from adlaide to melbourne.

All you can try is sheeting the headsail in hard amidships and easing the main and mizen right out. Maybe dropping the mizzen will work, or maybe dropping the main and driving off the mizzen. Sheet to tiller works but you need to know how to rig it up.

At least the weather is good. Make the most of it, sleep when you can and take care when you are tired. Dont push your luck, heave too and sleep, fatigue is an absolute killer,(please ignore my earlier joke about hardning up!) The tamar river mouth is not a good place to be in a rising NW when you are drop dead tired.

You might also be able to do something creative and hook up the st1000 to a bit of rope that is tied to the tiller or the trim tab. That way the autopilot can be mounted further away from the steel.

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Old 23-04-2016, 02:34   #183
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Re: Raymarine St4000 with Trim Tab Problem

Quote:
Originally Posted by Rustic Charm View Post
To get an auto pilot operating on a trim tab successfully I need some way of telling it that there are rudder stops. Or rather trim tab limits. Because that's what is going wrong now.
If you say that to a Raymarine specialist, they will always tell you to buy and install a rudder reference transducer (look back in this thread and you'll see that I mentioned a rudder reference transducer much earlier). But that's only one way to cook the goose. Getting the mechanical linkage right (i.e. the exact location where the ST4000+ arm or the ST1000 arm connects to the tiller of your trim tab) should solve the problem.

Quote:
Ann's probably right, I need to look at getting a windvane.

I'm in three minds about that. It's not a simple binary either/or thing.


I have a windvane and the apparatus to use the windvane to Led Myne's trim tab. And use the windvane at times.


But in years of cruising, I reckon I have clear evidence that my Autohelm ST1000+ operating on the trim tab (or the ST4000+ GP operating on the main tiller) does a better job than the windvane for long distance bluewater work.


In coastal work/pilotage waters, the windvane is mostly fine. But not always - take the example of a passage that ends with crossing the Wide Bay Bar, entering The Rip, or entering Torres Strait.


In each of those three cases, you need to be at a waypoint at a certain time determined by the sun and the tide (it's no fun trying to cross the WBB from seaward in the afternoon with the sun in your eyes; and timing the tide is crucial in all three cases). A windvane does not run as tight a course as an electronic autopilot, so there is a risk of losing an hour or three while enjoying a sail with the windvane keeping you on a constant wind angle (but the wind may be quietly changing direction and leading you astray).


For long distance work, when being off course a tad can mean a difference of a day or two extra in a passage (which can mean have to cope with a squall that could have be avoided if you made port a day earlier), an electronic autopilot does a better job - but I hasten to add that I feed wind data, water speed data, and GPS/GNSS data on my SeaTalk bus. So my autopilot is not steering only to a compass heading.
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Old 23-04-2016, 03:18   #184
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Re: Raymarine St4000 with Trim Tab Problem

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Originally Posted by Alan Mighty View Post
If you say that to a Raymarine specialist, they will always tell you to buy and install a rudder reference transducer (look back in this thread and you'll see that I mentioned a rudder reference transducer much earlier). But that's only one way to cook the goose.
I did consider it. BUT, I pretty much concluded that a 'rudder transducer' is attached and indicating where the main rudder is, not where the Trim Tab rudder is? Is that correct? And how would a Transducer help anyway?

[/QUOTE]Getting the mechanical linkage right (i.e. the exact location where the ST4000+ arm or the ST1000 arm connects to the tiller of your trim tab) should solve the problem. [/QUOTE]

Yes, it seems to me that the closer in I put the AP on that arm I had welded on, the worse the problem. The linkage arm is currently at 100mm and 175mm. I found the 100mm one was too close and as Atoll said it would use less power, but if the boat does not correct course quick enough then the AP over reacts on this short set up. It did it far less on the furthest out which is 175mm. Does it require to be even longer?

[/QUOTE]I have a windvane and the apparatus to use the windvane to Led Myne's trim tab. And use the windvane at times.But in years of cruising, I reckon I have clear evidence that my Autohelm ST1000+ operating on the trim tab (or the ST4000+ GP operating on the main tiller) does a better job than the windvane for long distance bluewater work.In coastal work/pilotage waters, the windvane is mostly fine. But not always - take the example of a passage that ends with crossing the Wide Bay Bar, entering The Rip, or entering Torres Strait. In each of those three cases, you need to be at a waypoint at a certain time determined by the sun and the tide (it's no fun trying to cross the WBB from seaward in the afternoon with the sun in your eyes; and timing the tide is crucial in all three cases). A windvane does not run as tight a course as an electronic autopilot, so there is a risk of losing an hour or three while enjoying a sail with the windvane keeping you on a constant wind angle (but the wind may be quietly changing direction and leading you astray).[/QUOTE]

Interesting. The reason I liked the idea of the electric AP is because I'm unlikely to do anything beyond coastal cruising. So I thought an AP for that reason would be sufficient.

[/QUOTE]
For long distance work, when being off course a tad can mean a difference of a day or two extra in a passage (which can mean have to cope with a squall that could have be avoided if you made port a day earlier), an electronic autopilot does a better job - but I hasten to add that I feed wind data, water speed data, and GPS/GNSS data on my SeaTalk bus. So my autopilot is not steering only to a compass heading.[/QUOTE]

Would you have a photo of your set up available?
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Old 23-04-2016, 03:20   #185
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Re: Raymarine St4000 with Trim Tab Problem

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Originally Posted by Snowpetrel View Post
RC, you have a good forcast. The mizzen is the tool you need to get the old girl steering herself. You will figure it out, or you wont, but basically sheet it in to steer into the wind, ease it to bear away downwind.

Motoring in a light headwind I would drop everthing except the mizzen then play with the sheet and rudder until she holds a course.

Use the old autopilot as a offcourse alarm so you can doze in the cockpit in marginal conditions.

Drop (or reef)the mizzen in strong beam winds and sheet the headsail in tighter than it should be. Play the main (and mizzen if its up) to get the course close.

Once the wind goes aft of the beam thats where life gets interesting. Ive only sailed one boat that would reliably hold a course downwind with just a lashed helm, that was a sistership to Suhali that I delivered from adlaide to melbourne.

All you can try is sheeting the headsail in hard amidships and easing the main and mizen right out. Maybe dropping the mizzen will work, or maybe dropping the main and driving off the mizzen. Sheet to tiller works but you need to know how to rig it up.

At least the weather is good. Make the most of it, sleep when you can and take care when you are tired. Dont push your luck, heave too and sleep, fatigue is an absolute killer,(please ignore my earlier joke about hardning up!) The tamar river mouth is not a good place to be in a rising NW when you are drop dead tired.

You might also be able to do something creative and hook up the st1000 to a bit of rope that is tied to the tiller or the trim tab. That way the autopilot can be mounted further away from the steel.

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How do I use it as an alarm? Do you mean just turn it to 'auto' as if its plugged into a ram?
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Old 23-04-2016, 03:29   #186
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Re: Raymarine St4000 with Trim Tab Problem

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that's great ,and yes making say three holes in the trim tab lever at say 10cm,12.5cm and 15cm will give you that dampening/amplifying effect from null point(15cm) that alan talked about.

also as alan pointed out there is very little force required to move the trim tab so the shortest lever will give the fastest response,and least power draw.

the only issue I can see is if the wind drops and the boat stops moving with the ram still trying to steer.
which might bend the trimtab lever if it is at its maximum travel before the ram is fully extended?


does the auto pilot have the rudder angle sender unit attached,as this might confuse it,as it is not actually moving the rudder?
Looking back through the thread, this is exactly what was happening I think. Except that it not only occurring when the wind dropped, but when heavy winds and instead of bending the trimtab lever, it pops out of the pin. And I think with what happened today, has damaged the motor inside.
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Old 23-04-2016, 03:31   #187
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Re: Raymarine St4000 with Trim Tab Problem

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How do I use it as an alarm? Do you mean just turn it to 'auto' as if its plugged into a ram?
Yep, that was my thought. It should beep away if you go off the set course, unless the ram being faulty causes it not to go into auto properly for some reason?

I had a thought about the failure mode of the ST4000gp. Did you end up setting rudder stops on the autopilot, if not maybe it pushed the trim tab over too far and locked the autopilot ram up against the hard over trim tab. If it did this regularly it would be very hard on the gears and the motor.
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Old 23-04-2016, 03:33   #188
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Re: Raymarine St4000 with Trim Tab Problem

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if the length of travel of the ram is 17cm.
then have a 8.5cm control arm on the trim tab.

this will give 45degrees of travel each way(from center position on the tab. this should be plenty(centers are tab axis and pin)reducing this length will give more than a total 90 degrees travel of the tab,extending less.

the inboard bracket on the tiller arm can be mounted out of perpendicular if clearance is a problem,(ie make the centers longer than 8.5cm) but when fitting make sure the ram is extended to half its travel length so the trim tab remains centered.

( you will have to check the ACTUAL length of travel on your ram,then devide by 2 to get the optimum trim tab arm length)

edit: I checked raymarine for st4000 ram,and it is giving me 31.6cm ram travel length,so optimum trimtab lever arm would be 15cm which will give slightly more than 90degrees of travel on the trim tab
Should I make the trim tab leaver 'longer' so that it can't travel more than 90 degrees? Though, I've been using it on 170mm and it's still not enough?
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Old 23-04-2016, 03:36   #189
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Re: Raymarine St4000 with Trim Tab Problem

Funny Alan, I pretty much used my flemming wind vane everytime I was sailing. I used it to tack, gybe reef etc, and I only really broke out the 4000 for motoring, or inshore waters where I needed a precise course in shifty winds or couldn't be bothered locking the servo pendulum down.

I often tweaked the course, and I guess if I was singlehanding a lot the accuracy would be more appealing, but either way windshifts still cause issues.

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Old 23-04-2016, 03:53   #190
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Re: Raymarine St4000 with Trim Tab Problem

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Yep, that was my thought. It should beep away if you go off the set course, unless the ram being faulty causes it not to go into auto properly for some reason?

I had a thought about the failure mode of the ST4000gp. Did you end up setting rudder stops on the autopilot, if not maybe it pushed the trim tab over too far and locked the autopilot ram up against the hard over trim tab. If it did this regularly it would be very hard on the gears and the motor.
I think this is what happened yes. But the damage is to the motor. I've had it pulled apart and the motor itself won't turn. It tries too. But can't.
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Old 23-04-2016, 03:57   #191
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Re: Raymarine St4000 with Trim Tab Problem

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Originally Posted by Rustic Charm View Post
Looking back through the thread, this is exactly what was happening I think. Except that it not only occurring when the wind dropped, but when heavy winds and instead of bending the trimtab lever, it pops out of the pin. And I think with what happened today, has damaged the motor inside.
yes this was a worry with these powerful units,and no rudder reference unit fitted.

can you just clarify if you managed to unscrew the tube that houses the electric motor.

if you can get the motor out,(it just slots in place in the housing)


the electric motor made by singer,is sealed by 2 tabs bent over the back end that holds the brush assembly,but in the past I have unbent these 2 tabs allowing me to replace or clean the brushes then rebent the tabs back in place to get the motor working.

I also once had to resolder one of the wires that had broken off on the brush holder.

if however one of the cogs in the gearbox is broken,then its fuked!

it might be worth exploring this option,though being under warranty,might not want to leave tool marks etc
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Old 23-04-2016, 04:00   #192
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Re: Raymarine St4000 with Trim Tab Problem

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Originally Posted by Rustic Charm View Post
I think this is what happened yes. But the damage is to the motor. I've had it pulled apart and the motor itself won't turn. It tries too. But can't.
I posted before seeing this,see previous post

,so there is a good chance that you can get the motor going again if you can inspect the brushes
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Old 23-04-2016, 04:11   #193
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Re: Raymarine St4000 with Trim Tab Problem

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Should I make the trim tab leaver 'longer' so that it can't travel more than 90 degrees? Though, I've been using it on 170mm and it's still not enough?
no you need to set stop settings in the calibration programm.

on earlier units without the rudder reference unit,the micro processor would stop the auto pilot once it sensed a high amp draw from the motor if it reached its stop ,this I belive relys on the reference unit or program to stop the motor.
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Old 23-04-2016, 04:37   #194
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Re: Raymarine St4000 with Trim Tab Problem

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Should I make the trim tab leaver 'longer' so that it can't travel more than 90 degrees? Though, I've been using it on 170mm and it's still not enough?
From page99 of the 4000+ book it says the minimum (and default factory set) rudder stops are at 15 degrees. If my maths is right on the normal 460mm distance out on the tiller thats about 124mm of travel, so the minimum setting shouldn't bind up on the trim tab at 170mm

So unless you had accidentally adjusted it it shouldnt have bound up on the 170mm setting, though it could have on the 100mm setting.
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Old 23-04-2016, 04:47   #195
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Re: Raymarine St4000 with Trim Tab Problem

here are a few photos of a "sealed" motor dis-assembled to expose the brushes,this is not a "singer" which as carbon brushes,this one has brass contacts,but the set up is basically the same.

cleaning the contact surfaces on the brushes and armature generally does the trick to get the motor working again
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