The dangers of electronic controls

DK how that's even possible unless he was backing in way too fast to begin with.

DK how that's possible either. When I teach, my favorite expression is "slow is cheap", and when I see a guy blasting his boat into his slip to look cool 'That's a guy who's never had a throttle cable snap'. My money's on human error causing most of that damage.

Electronic controls are great when they work and they are horrific when they don't. More than once have electronic controls (Microcommanders anyone?) told the gear to do something independent of the input from the helm operator. Quite surprised you've never heard/didn't know that it was possible for electronic controls to not obey the input from the helm NYCap. Your lost your money on this one.

In this case the controls told the gear to stay in reverse and told the engine to give full throttle. The captain DID press the engine kill switches, he DID put the single levers in forward. The captain is experienced and well respected. He was NOT backing into the slip where the incident occurred- his slip was on the other side of the waterway at a completely different marina. He is not of the habit to back into the slip at a speed faster than the speed you want to hit the dock.

Of those that had actual visual of the incident - all agreed the captain did everything in his power to stop the reverse movement of the boat. The boat was not under command. ALL captains who were at the scene agreed the accident happened because of the failure of the controls- NOT the failure of the captain. I was there.

That is indeed the case.

i cannot understand what could cause this to happen of its' own accord ...

Hi,

I was on a boat once when one of the tenders with Volvos and electronic controls decided to jump into gear by itself when the radio was keyed.

Turns out the Antenna cable was loose.

MTU's used to have their electronics installed in a substantial steel case to try and prevent stray currents causing issues.

In my opinion the best belt and braces Emergency stop is Air Flaps manually released if possible.

More and better pictures in this earlier thread:

http://www.yachtforums.com/forums/g...fish-silver-fox-accident-sailfish-marina.html

As mentioned in the other thread I don't understand how a control failure can also prevent the shut down switches from working, unless MTU has everything tied up their a central ECU, which seems like a very dangerous options.

With the Cats and morse controls I familiar with, the controls have their own ECUs Nix even if they go bananas the shut down switches will not be affected.

Experience has shown you that electronic controls can have issues. I have had similar experiences. Excellent advice on the manual release air flaps if possible.

I have heard that a dead short is basically full reverse on some of these controls. And and open circuit is full forward. Is there no failsafe? For a system that important I would think you would design in some simple redundancy such as dual circuits. Also you would want the circuit to be within a range to be considered operational. Say 1000 to 10,000 ohm or similar.

If the circuit fails the criteria in any way then reduce the engines to idle.

Educate me - why don't they work this way.

You can build electric controls in a myriad of different ways. You usually can't tell without taking it apart or digging into technical document. (Which I did not.) Some variants like the one you have described are obviously dangerous since disconnects and shorts can occur at any time. On this side of the big pond I would say: Hello product liability.
I come form the industrial electronics and automation side of things where we have strict rules to what you can or shall (legalese shall) do. Neither safety nor failing in a safe manner are optional. But these rules and regulations usually got enacted after too many people got squished and -arguably more importantly- the mandatory insurance fees went through the roof.

On the process control side the good old 4-20mA current loop is the ususal example for an electric control has quite a few inherent safe failure modes. Later (1980's) a digital component has been added, see HART protocol. Modern digital bus systems like CAN (aka NEMA2000 in the marine world) of course also have build in safeties to detect different kinds of error conditions.
The story of course does not end there. What does the control unit do when a communication channel e.g. the throttle control throws an error? Is the control unit itself affected? (Say high power HF radiation from a loose connector at the antenna tuner, located for some reason in the ER.)
And so on and so forth. The chain of events does apply to more than just aviation.


But back to this case, the first question always is:
What did the human actually do? - According to the other thread the skipper did the right things. So we move from gross human error to the technical side and ask more questions.

Which systems were installed?
Are they compatible?
Are they known to be unsafe? (Recall, loss of certification, ...)
Where they installed correctly? - Say the emerg. shutdown only wired to only to one engine.

Any after market modifications or "fixes"? - Bye bye manufacturers product liability, welcome back human error.

And last for this little list but not least:
Were there known defects?

Don't underestimate the last one. The insurance company will take a quiet but close look since a known defect which not has been addressed and led to an accident can offer an easy out. Negligence is a very expensive word.


Do we know what happened? Not yet.

Locked in reverse gear

A few years ago I witnessed a brand new sportsfisher with a highly experienced and respected captain at the helm do major damage to the hull while backing into the dock. In this case the Microcommanders locked him into reverse. He was coming slowly into the pen, when he pulled the gears into neutral she kept reversing. He then selected forward and she kept in reverse. Thinking it was only the boats momentum, he gave her more throttle and the sportsfisher just about jumped through the dock before he could kill the engines. That was his first experience with electronics after using cables for than 20 years.