Public Discussion Forum

Hi, LC.

The failure mode under discussion in this thread would not have the tendency to cause a shift reversal while underway, but only a failure to return to neutral at some point in time later, and even then probably only when shifting from reverse to neutral.

Hopefully your crossing was all happy and the problem never finds its way aboard Ho’okipa.

Aloha!

Jim

The two servos are similar in components, but their gearboxes are configured for different functions. The shift servo’s zero point is in the middle of the range with 45 degrees plus and minus for forward and reverse shift. The throttle servo’s zero point is at one end of the range.

Did Twindisc refurb your unit? You’re very lucky there. I’m hearing that they’ve orphaned them.

Of course! Though I can’t guarantee that I’ll hear and answer in the middle of the night.

Dear Jim,

As I'm crossing the Baltic Sea in rough seas, I read your post. May I call you 24/7 if I start have issues with my EC200 Twindisk?

~LC

mv Ho'okipa

S4326

A few readers have asked me how to identify whether they have a Power Commander control unit of the type relevant to this discussion. Here's how to verify:If you have propulsion control stations like shown in the first pic attached here, then go to your engine room and find the Power Commander control box for those EC200 controls. If that unit is like the one shown in the second pic with a gear shift lever, then you have the version that is susceptible to the same shift failure with age.

A member asked me privately whether a wireless controller could be a factor in the shifting issues. I'm sharing my response here for others who may have the same question.

I can say with absolute confidence that the wireless controller had no possible role in the gear-lock failure that I experienced. Even leaving out the failsafe emergency functions of our system, I was able to repeat the symptom 100% of the time after completely disconnecting our base station from the boat’s wiring. We further disassembled the Power Commander control box and positively identified the failure of the servo motor.

I have also been called in as a consultant to examine helm control malfunctions on numerous boats where either Yacht Controller or Dockmate controls were suspected to be the cause of undependable or erratic shift events. In each case I eliminated that possibility with complete certainty by firewalling the wireless control system from the boat wiring, and then instead found the power supplies to the shift control boxes (various brands) to be suffering from undervoltage in the case of reverse-stuck failures on other brands, and overvoltage in the case of unauthorized forward shift events.

The problem of reverse-lock critical failure is not unique to the Twindisc EC200 system; I understand from talking with colleagues that similar failures have been seen in older analog controls from other manufacturers too. There are significant benefits to upgrading to newer CANbus controls. The linear actuators in the mechanical shift control units are substantially more accurate and dependable than the rotary servos in the older units, and the self-diagnostic functions provide additional safety that is lacking in the older units. A well-designed system includes an easy means of switching back to mechanical operation in the event of a failure of the electronic controls, which is handy for getting home in an emergency.

To determine whether your boat is susceptible to the failure I described in my original report, start by looking at your helm’s propulsion control head; if it is an EC-200, then go down to the engine room and look at the tail end of the transmission to see if there is a push-pull control cable connected to it; if there is a cable, then it is driven by the Power Commander control box and is susceptible to same failure. I’ve seen this failure on boats with as few as 1,000 total hours operating time, and there does not appear to me to be any pattern of other identifiable contributing factors.

I agree with all of your first paragraph, though the problems that I have seen on various vessels didn't involve the final shift cable linkage. Those always appear to move freely and properly. More specifically, the problem invariably has been in the servo motor in the Power Commander driving that final shift cable. (When converting from older Morse cable controls and similar, I frequently see binding problems in the mixer controls where the upper and lower control heads combine to drive the final shift cable.)

However, I have to disagree with your distinction regarding the existence or absence of a Power Commander unit in the EC200 systems. Every Twindisc EC200 system includes a Power Commander control unit, even those with only electronic throttle and transmission. The control heads communicate their requests to the Power Commander, and the Power Commander sends the appropriate voltage shift signals to the transmission and - in the example of a Lugger or Deere engine - sends a variable 0.5-4.5v output to the engine for throttle setting.

Somewhere in your boat there must be a Power Commander control box, since that is the point of power-up for all other components, and for interface with your engine and transmission. If the propulsion control architecture on Koinonia does not include a Power Commander control box, then that fine vessel is truly more unique than I previously imagined.

Hi, Mark. You are correct that this issue is limited to EC200 systems that connect to mechanically-shifted transmissions and does not affect those systems without mechanical actuators, as those EC200 systems do not involve servo motors but simply send voltage signals to the shift solenoids on electronic-shift transmissions. I have not yet come across any failures of EC200 systems failing to send the appropriate voltage shift signals.

Greetings, fellow Seleners! I'm writing today to alert those whose boats are equipped with Twindisc EC200 electronic helm controls operating mechanically-shifted transmissions of the potential for critical failure of the Power Commander shift control.

Some of you know me as the current owner of Alyeska, a 2001 Selene 47, as the developer of a wireless docking control system, and an independent service tech on electronic vessel propulsion controls generally. Over the past few years I've been on many boats to consult on helm control issues, and to replace older control systems with newer CANbus-protocol controls. Within the past twelve months I've examined a handful of EC200 systems which had suddenly developed the worrisome tendency to get stuck in reverse gear. The initial symptoms in each case were an unusually-slow return from reverse to neutral, followed by a permanent stuck-in-reverse within a few days afterwards.

I've seen multiple examples of similar anomalies on other helm control systems, both with mechanically-shifted and electronic solenoid-shifted transmissions, but in each of those cases the problem was resolved by correcting under-voltage or over-voltage conditions at the control computers.

But on the Twindisc EC200 Power Commander the problem each time has been the failure of the internal servo motor that drives the Morse cable connected to the mechanical shift lever on the transmission. Unfortunately, to the best of my knowledge there are no replacement parts available for these units, as Twindisc has long ago orphaned the EC200 analog systems in favor of newer CANbus technology as has been the trend with all competitors. Although I've had some success at reviving a failed servo with custom-engineering, I would not consider it a viable solution due to the overall age of the components (20+ years) and the likely cost of a critical failure when docking. The only reasonable solution is complete replacement of the helm control computer/actuator and control heads with a new system.

Prior to this past weekend I assumed (perhaps somewhat arrogantly) that this failure mode was something that only happened to other people's boats, and that Alyeska's EC200 helm controls were not susceptible to the same failure because, well... because I have been diligent in their care and maintenance. But on this past Sunday while anchoring at a sandy spit at a somewhat crowded anchorage I found myself suddenly the newest member of the Twindisc EC200 reverse lock club. Despite my self-assured confidence in the superiority of my situational awareness, my boat backed almost 75' before I realized the problem and scrambled to shut down the engine and wait for the anchor to bite as we drifted briskly back towards several other boats anchored. Luckily the anchor finally grabbed and stopped us just as I was using the thrusters to turn the boat to try and steer clear of an incursion. I'm sure that I wasted at least a few seconds on disbelief and denial before accepting the reality of the situation and shutting down the engine. I shudder to think what would have been the result if this EC200 failure had instead struck earlier in the day as we were departing a tight slip in a crowded marina, surrounded by many boats more expensive than my own. This would have been a very different report in that case.

As with all of the other EC200 failures that I've seen, only the gear shift function was impaired, and throttle functions remained intact. So, in order to ready the vessel for return home I disconnected the shift cable from the Power Commander control box, manually checked the transmission for normal shift capability, and then yesterday we weighed anchor and returned to our moorage under slightly impaired maneuverability by shifting the transmission manually in the engine room -- a somewhat cumbersome operation when nearing our dock, but not unmanageable.

The takeaway that I would urge from this story is that if your boat is equipped with a manual-shift transmission and a Twindisc EC200 system, please give some careful consideration to replacing that older and now long-outdated system with a modern control system using CANbus architecture. The safety improvements in these newer systems easily justify the cost even if your old system is not "yet" showing any indication of failure, just as mine was perfectly happy until it was suddenly not happy.

A new Twindisc EC300 system to replace your EC200 system will likely cost in the neighborhood of $30,000 USD, but that's not your only option. For example, I'm a dealer for another manufacturer (Japanese), and have installed replacement systems on a handful of boats at a total cost about 1/3 the price of that with excellent reported results, so this is need not be an excessively-expensive precautionary upgrade, and is vastly less expensive to do BEFORE a critical failure in a crowded marina.

I'm available to chat with fellow forum members who would like a little bit of coaching on their own DIY upgrades. My contact info is in my profile, and you can DM me.

Jim Martyn

Alyeska

47-07