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Jeffa Autopilot Failure

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colinc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote colinc Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2020 at 06:00
Thanks for that info.  I am sure of interest to all 505 owners.

On the option of keeping the DD1 do they recommend how to go about moving to that outer hole?
1. Reducing the angle through which the rudder operates so not taking the drive too far either end
2. Changing the length of the push rod so that the middle rudder angle is at the centre drive position

In other words can they provide an amended “build card”?

On the option of the DD2 I am sure others would be interested in upgrading too.  Presumably Jeffa would offer that as an easily orderable upgrade?
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jdderijke View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdderijke Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 01:52
Hello, it’s been a while since I reported on my problems with the DD1 drive on board of my Hanse 505 Privateer. It broke 1 day outside of Cape Verde, we went back and repaired the drive. And then it broke again in the midst of the Atlantic and we where forced to hand steer for 1 week…..day and night…. before reaching Grenada. The second breakdown was likely a poor repair job done in Cape Verde, we couldn’t get the spares into Cape Verde on time so we decided to have a local machine shop repair the broken gears…they did not last long...

Since then I have replaced the planetary gear wheel and the main drive axle with new Jefa parts. And now the unit is starting to break down again…. Making clonking noises…the beginning of the end.

I did not move the drag link to the outer hole because I don’t think it makes the difference. As I mentioned earlier the gears (in my humble opinion) don’t break because of the DD1 putting force on the rudder, but because of the rudder putting (a lot, a whole lot) of force on the DD1 during surfing on ocean waves. I have always had the problem start when large waves came from behind and the waves broke just behind the boat.

Anyway…..I have moved on and installed an electro-hydraulic solution. I bought a Hypro linear drive, they have a new one that fits in the Hanse 505 autopilot compartment.

I have made an adapter plate of 15mm aluminum and 15mm epoxy glued together, this plate fits exactly on the mounting holes of the DD1 and is fastened with the same bolts (M8). The Hypro linear drive is then mounted on top of the adapter and bolted in threaded holes into the epoxy-aluminum adapter.

I moved the DD1 drag-link to the outer position so that the DD1 could still be used as a spare autopilot. (to move de draglink-pin I used an extra high socket from a socket wrench (1-1/8 or 17/16 inch I think) and used it as a pull device with an M8x100mm bolt and a nut on top….works like a charm. Used the M8x100mm with a large ring on the bottom and a nut on top to press the DD1 link pin into the outer hole. 

The electrical clutch and drive connections are done with connectors so that I can change back to the DD1 quickly (if needed).

Finally I moved the rudder sensor to another position because it was linked with the DD1 arm….luckily Jefa already put a threaded hole in the tiller arm for this. 

The hydraulic linear drive has a Max Operating Thrust of 350kg (Intermittent) and a hard over time of 12 seconds. It consumes at typical conditions (60kg’s at 25%duty)  2,3Amps including the clutch coil, which I think is pretty good.

 

Dockside installation was successful, we will do sea trials later this week.

I will keep you posted on my experience with the Hypro drive. 

For those interested: Details on the Hypro drive..

 https://www.hypro.co.uk/products/hydraulic-pumps-and-steering/linear-actuators/ml40-compact-marine-autopilot-electro-hydraulic-linear-actuator/



JD
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colinc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote colinc Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 08:37
The installation looks very neat.   However have you checked the force rating of the linear drive?

The Jefa DD1 you are replacing provides 150kgm torque. At the end of its drive arm 130mm long it provides 150*1000/130 kg or 1150kg linear force.  Not sure your replacement provides that?  Although a hydraulic system is probably better able to survive overloading with relief valves etc.

I note that the bigger brother of your drive (the ML+40) is the same as the B&G T2 drive. That is the size B&G recommend for our boat size and displacement.  It has 700kg max thrust. Also uses a longer tiller arm so actually about three times the power to the rudder as the one you fitted and similar to the Jefa DD1 power.  Presumably that bigger drive would not fit?


Edited by colinc - 14 January 2020 at 12:59
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Sea-U View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sea-U Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 13:27
"I did not move the drag link to the outer hole because I don’t think it makes the difference."

!!!???

It matters a lot what hole you use. Using the outer hole will need a lot less force to hold the rudder.
Sea-U is a 370e #532 located SW Norway
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jdderijke View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdderijke Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 15:01
the inner hole to center rudder post is 17cm, the outer hole is 20cm from the center of the rudder post. So the forces are 15% less in the outer hole. De DD1 gear breaks because all the force is hold by 2 teeth on the planetary gear axle. IMHO 15% less force with the forces i have seen on that rudder wont make the difference when surfing or broaching. If that gear was engineered to be over dimensioned (good engineering practice) then it should have survived that 15% extra load. My opinion is that the DD1 is fine in normal conditions, but under dimensioned for following heavy seas. The Hypro may be less powerful in terms of kgf, but when overloaded through push back from the rudder the relief valve will act better than the gear teeth of the DD1.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdderijke Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 15:04
truth be told.....i havent actually tested the Hypro in these conditions yet...
JD
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colinc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote colinc Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 16:17
I think you are both right actually.   

The geometry of the DD1 installation increases the torque to the rudder by virtue of the way it is linked up.  The calculation works out as 190kgm torque on the inner hole and 230kgm on the outer hole (as being the actual torque on the rudder itself).   So that is a 20% increase in torque applied using the outer hole.

However the reality is that both of those should be sufficient as straight torque.  The B&G T2 drive, for example, provides, coincidentally, 190kgm at the rudder.  So presumably that is enough to steer the 505.  Maybe a marine engineer would say if that is correct.

So the inner hole should be enough torque.  And presumably Hanse knew that when the built the boat using the inner hole.   The “problem” with the outer hole is it does not provide the full 72 degrees rudder movement.   Although, as explained above, that may not matter.

So why is the DD1 failing?   That is the crucial question.   

One theory is that the lesser movement wears the cogs over a limited movement.   I don’t buy that myself as I had a DD1 drive in my Hanse 370 for 12 years with no problems at all.  And my 505 “works” the rudder far more than the 370 did.  I don’t think that theory feels right.

An alternative that comes from the discussion above is that the 505 throws far higher peak loads on the rudder system.  I only sail in the Med but have experienced the dancing aft with waves from the aft quarter.  A question for anyone still reading this :-) that has had the 505 fail is, did you sail in such large following seas immedately before the drive fail?   And I think we are talking ocean rather than sea sized waves.

If that theory is right then the problem is peak loads on the rudder caused by the size and shape of the 505 stern that break the DD1 drive by overloading.

Placing the drive into the “outer hole” reduces those peak loads by 20% and that may be enough.   It also adds a bit more “give” in the system with the longer drive.  If so using the outer hole is an answer.  

If you use the outer hole then I think the drive rod also needs reducing in length a little to bring the mid point of the rudder at the centre point of the drive unit.   My drive rod is already at its shortest setting when in the inner hole.  So I need to replace it with the next size down from Jefa.   This may not matter but I’d prefer the geometry to be symmetrical.

The alternate to the “outer hole” is a larger drive from Jefa or someone else.  I think rather than seeking extra maximum torque one needs to think about resiliance to peak loads that will be much bigger than normal use. Maybe hydraulics, for example, has better resiliance to peak loads than a direct drive unit.    It would be interesting to hear from Jefa on that one.  It partly depends on whether their electronics handle an overloading situation.

For those that have experience failure of the DD1 does this sound plausible?


Edited by colinc - 14 January 2020 at 16:25
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ohthetrees Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2020 at 20:31
See below for update about pricing for the DD2 kit. I'm American, so VAT not included.

I haven't heard back yet about conlinc's questions about drag link length and whether greater range of motion are of concern. Personally, I think I will give repairing the DD1 a try and see how it gets on with a proper installation as Jefa drew it up. In that case, I will shorten or replace the drag link, and I will use the B&H dock side configuration to program a smaller range of motion. When I tried my rudder, I think I recall the physical stops were at +- 46º. I intend to program in +- 30º, which I think is adequate range of motion in all circumstances I anticipate using an autopilot. If the autopilot needed to command 45º I have other problems. 

Regarding jdderijke's project, I completely understand why he has lost faith in the DD1. But I also feel it is a little unfair to judge to product when we know for a fact it is improperly installed. It seems to me that a 20% reduction in force could make a real difference. Also, are we sure there isn't a larger reduction? The math is beyond me, but not only is the tiller arm length greater, but the angle is different too.

Regarding the hydraulic ram, I certainly admire jdderijke's ingenuity, and hope it performs well, but I worry it is undersized too. Personally, if I find the repaired DD1 inadequate, I will either upgrade to the DD2, or use the Jefa retrofit kit parts for an under-deck installation, minus the DD2 itself, and install a large hydraulic ram system. The Jefa retrofit kit should make this fairly easy. An under-deck system also has the advantage of being in a water-tight space.



CodeDescriptionPrice in €
550004 x plates €         379
1. plate: 480mm x 550mm x 10mm
2. plate: 480mm x 100mm x 10mm
3. plate: 480mm x 200mm x 10mm
4. plate: 200mm x 220mm x 10mm
TLJ100Tiller lever c/c250 mm, max. bore 100 mm, incl. bore and keyway €         327
TLJCONsurcharge for conical bore €           63

Plus 2600 euro for the DD2 itself. 
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kipwrite View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kipwrite Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2020 at 01:27
A few things to add here:

In the case of my DD1 failure (see original post in this thread), we were in the Gulf Stream, surfing in a fairly steep 7-10 foot following sea, with the ram in the inner hole. So I think this failure matches Colinc’s theory. 

Since we moved the ram to the outer hole, no issues. 

Curious what an under deck installation might look like, but I’m glad to hear that a Jeffa has developed an alternative solution for our boats. 

And of course would love to hear how the HyPro unit works over time. 

Appreciate the counsel of the engineers in this forum, and especially that it appears we have some good options emerging beyond the Hydrovane and being cautious with our DDI drives at sea. 


Edited by kipwrite - 15 January 2020 at 01:52
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ohthetrees View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ohthetrees Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2020 at 04:47
Out of curiosity, does anyone know what the autopilot setup is of the 508? A quick google search did not reveal the answer.
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