Raymarine Autohelm Failure

[helenbates]

my husband is part of a 4 man crew currently rowing acrodd the Atlantic. They are using the SPX5 raymarine autohelm system. In just over 3 weeks 2 autohelm arms have failed - both now simply fully extend and lock when engaged. They cannot identify a fault as the motor works fine when plugged directly to 12V and computer works fine with 3rd (and final) new arm. Has anyone experienced this problem and if so found a solution? Any help/thoughts appreciated.

[Snowpetrel]

Is the ram (arm) unit inside or outside? If outside its possibly water getting into the ram and damaging whatever senors/electronics are inside the ram to monitor and control the ram position.

The other possibility is corrosion in the plug. Normally this results in the unit failing to move at all, but prehaps a bit of corrosion and added electrical resistance here is affecting the rudder angle sensing system somehow. Easy fix is to bypass the plug and hard wire it to the autopilot control head.

These tillerpilot type units are not particularly waterproof (having drowned two) They are more like splashproof so to protect the final unit a waterproof cover made from something might help, as well as limiting its use in severe conditions. Prehaps modifying the mount to get it inside, or up higher, or mounting it so the ram unit angles down and water flows away from the vulnerable ram seal.

Matt (islandtime) on here knows a lot about autopilots. prehaps worth a PM.

I dont know how you dissasemble them, but this might be an option on a dead unit to at least determine if its water ingress. Sometimes you get lucky and can dry out and clean up wet and corroded electronics and get a bit of extra life from them.

Have a look through Webb Chiles blog. He has had multiple failures on his small boat round the world. Probably up to number ten unit by now..

Sounds like a hard trip. I can't begin to imagine how hard rowing across an ocean would be.

[Wotname]

Welcome aboard CF helenbates. Let's hope we can collectively help in finding the answer.

One suspect must be corrosion, possibly light corrosion somewhere between the motor and the computer. Presumably the motor reverses direction by a change of polarity (i.e. + to - and then - to +).

Light corrosion can sometimes act as a diode which will allows the current to flow in one direction but not the other.

[Snowpetrel]

http://www.bristolsailboats.org/wp-c...08/st40001.pdf

This is a link tp the older st4000 unit repair manuel. I suspect (but can't be sure) that the new units ram is similar or the same. Pg 21 and 22 contain information about stripping and troubleshooting the ram. And it also has valuble information about simple resitance and amperage tests for the ram.

Seems like they are a straightforward bit of kit with no fancy circuit boards in the ram unit, so I am not sure how they sense end of travel or ram position. Possibly with an amperage shutout at end of travel?

A little bit of corrosion in the plug or wiring could still be the cause of issues. I know when my st4000 failed hardwiring it and bypassing the plug got her running again, but I cant remember the symptoms...

I like wotties thoughts on the diode effect. Or possibly it takes more effort to pull the ram in, and it stalls the motor one way?

[helenbates]

Thanks for all your replies. They mean nothing to me but I will send them on to the boat and hopefully with all those suggestions they can find a way to fix it.

[Snowpetrel]

Good luck with it, and their trip. I will be interested to hear how it all pans out. Do you have any links to a website?

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[helenbates]

Thanks! Here is a link to their progress tracker.
World Record Atlantic Crossing Attempt - Ocean Rowing Events

[helenbates]

Thanks for all your replies.

Still no joy and now the third arm / unit has failed.

These were all good suggestions but the weird thing is that the units work when directly on the 12v so it's not corrosion etc.

Any other advice or where else I might post this much appreciated.

Thanks!

As for following their progress - this is the link. Though unfortunately progress has currently been halted until they can fix this... World Record Atlantic Crossing Attempt - Ocean Rowing Events

[helenbates]

Thanks everyone but unfortunately nothing has worked and now the 3rd unit has failed.
It is not corrosion however as the units work when directly on the 12v which is the strange thing.
They are now only half way across with no steering so if anyone has any further bright ideas they'd be much appreciated.
Thanks! Helen

[helenbates]

How can I Pm Matt (islandtime)?? Thanks!

[DeepFrz]

helenbates, it sounds like the computer is trying to steer them in the wrong direction so it isn't reversing the drive.

Could be a compass problem but that doesn't explain why it works for a while when they install a new drive.

Could be the smart rudder sense isn't so smart. Is there a calibration procedure for that?In the picture I didn't see a rudder position sensor.

Have they tried a power reset to the computer?

Is something reacting with the heading sensor, ie: compass?

Maybe the system is getting confused when the boat gets yawed to far from the desired heading and can't get back on track. Try powering the system down until the boat is on the correct heading and then set it to auto.

I hope this helps. I wish you all the best of luck.

Have you tried getting help from Raymarine support?

[DeepFrz]

I can't get to any of the Raymarine literature on the tiller drives. I get "access denied" message. Can anyone else get the info?

[helenbates]

Yes we've tried all the Raymarine help centres, Uk, US etc... but to no avail. Many thanks for your responses. I will send on. Best.

[DeepFrz]

It looks like they are still making good time.

[Snowpetrel]

Hi Helen, sorry to hear the last unit has failed, and its a shame Raymarine arent being helpful. Having the rams work directly on 12v power is great, it means they are basically functioning. Also since the control unit seemed to work fine with a new ram that likely rules out a control unit problem. That leaves the wiring between them (inc the plug) as a likely culprit.

Just because the units worked fine on a 12v battery doesn't mean corrosion isn't an issue. The battery can supply a lot of current, the control unit is limited, and senses and limits the current (I assume) to stop the ram moving to far or overloading. A small amount of corrosion in the wire could cause all sorts of problems..

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