Hello Sal,
This was raised last night by @New3M and I attempted to find some information to confirm either way. I found a comment on one article which stated that the three sister vessels were all fitted with CPP although they were unsure about the incident vessel.
A fluent Spanish speaking might find posts on Facebook by the cadets or their relatives , or former crewmen.
Basic info such as whether she is CPP or not is undoubtedly being discussed.
Someone stated that she has a CAT D399. That’s a1970s era engine of about 1100hp at 1225 rpm. Those rpms would require a reduction gear.
Sal,
This is interesting engineering commentary off a YouTube video. A hydraulic pump failure or control power failure can automatically put the CPP into astern mode.
It’s easy to 2nd guess but if I was handling that tug when I realized what was happening I would put the bow line immediately on the ships most forward accessible cleat. McAllisters fleet list shows her as twin screws Kort nozzles and flanking rudders. Proximity to the bridge made speed hooking up more important than were she hooked up and the bow was the place to be. Twin screw boat handles well pulling backward. I did just that often pulling out of a tight spot turning around then passing the main tow line from aft in open water, plenty of room to operate. Twin screw slow speed is more manageable in reverse and in this case faster to hook up.
However the tug in most ship docking is managed by the docking pilot on board the vessel. Would be unusual for the tugs captain to make his own plan. My experience mostly CG assist towing when we did a lot of it. Twin screw utility boats. When using the single screw 30’s never pulled backwards. Trawlers about the largest I towed picking them up from the offshore cutter or patrol boat & docking the CG Coxswain in charge not the disabled vessel. Situation very different that the Mexican vessel.
Boats3,
Great post which makes a lot of sense. 
Dr.Sal!!! EXCELLENT !!!
It was FANeffingTASTIC .And I mean it 
Just watched it and thoroughly agree with points made. There is also, once again, very good information contained in the comments section and I attach same.
All the talk about the default setting of a failed CPP being “go to reverse position” is new to me. But in my 29 years of working on floating things I never worked on tall ships or yachts. Here is what I’m familiar with.
The bridge gives a command & the CPP has a certain amount of time to reach that command or the gear/CPP will clutch-out.
Many systems will also place the unit into “Back-Up” mode whenever it cluthes out due to improper/delayed feedback signal.
After this happens, everything needs to be shut off, unit taken out of “Back-Up”, then restarted.
Below are memorable problems that comes to mind for me:
Problem #1: We had a stbd CPP that would clutch out & go to Back-Up very, very frequently while maneuvering. The only way to get it to operate normally was to run the standby servo electrical pump while maneuvering. While underway, the mechanical pump by itself was fine. It was later discovered the disc on the relief valve was pitted, allowing oil to flow back to sump, preventing proper pressure to be built up to move the the spool valve fast enough. Once the relief valve was changed, the mechanical pump running by itself was fine.
Problem #2. A CPP was moving very, very slowly while maneuvering. It was discovered the parameters of the CPP were changed in the past to prevent the CPP from clutching-out due to slow feedback response. The problem was a failing mechanical pump & instead of changing pump, they changed the parameters & lived with it.
Problem #3. A CPP was moving very, very slowly while maneuvering. It was discovered the parameters of the CPP were changed in the past to prevent the CPP from clutching-out due to slow feedback response. The problem was discovered to be a similar pitted relief valve & instead of discovering the problem they adjusted the parameters.
Problem #4. CPP stuck in 1 position & clutched out due to incorrect feedback response. Problem was due to O-Ring breaking & being jammed on spool valve & housing.
Problem #5. A bowthruster stuck in one position. It was a linkage that came loose & system didn’t have a feedback error shut off.
Problem #6. A steering gear got stuck hard over. It was discovered a magnetic solenoid coil overheated, swelled, clamping down on the plunger causing gear to stay hard over.
Problem #7. A gear box wouldn’t come out of 90% full ahead. This gear box was pneumatically controlled & the wires to the control unit came off & gear stayed in the last command given.
PROBLEM #8 &THE MOST COMMON!!! Bridge team calls Engine Room & say they have no control. Engineer (me) tells them to hit the “In Command” button because system is being controlled by another station, autopilot or DP. This fixes it 99% of the time from my experiences.
Sand_Pebble,
With respect, as a Marine Engineer, clearly you have not experienced this CPP failure default but it would appear that others have……not just in sail training vessels but also in the commercial arena.
If this is indeed the cause for the uncontrolled sternway, then it goes someway towards an explanation. The difficulty with CPP is that the auditory signals to the bridge team do not change as opposed to a fixed pitch installation whereby the propellor stops between direction changes. I can understand and sympathise with the bridge team if the CPP did indeed jam astern.
I’m not sure if this is relevant, but as a sailing ship wishing to reduce drag under sail, her CPP would likely have a setting for ‘feathered’. This may not be available in the more regular CPPs in normal use that many are describing here.
My experience with CPPs wasn’t positive having commissioned a new naval oceanographic survey ship in the early 80s with twin CPP main propulsion and a further feathering CPP active rudder (ie propeller incorporated in the ship’s single rudder) which rotated to 90 degrees. An early attempt at fully manual DP.
I spent a year aboard and departed with the system never fully accepted into service. The ship was not a success in service and eventually disposed of.
P.S. I note Sal’s difficulty pronouncing the ship’s name. From experience it sounded more like ‘kwon teh mock’ with emphasis on the first syllable. Not a biggie.
Unfortunately, as a Marine Engineer, I have experience hundreds of CPP failures in all sorts of directions. I just easily described 7 where I could give the problem & the solution. If I had to, I could give the name of vessel, year, location & captain. That kind of stuff is easy to remember. As for my # 8, that has happened too many times to recall them all. I was just stating I’ve never heard of a CPP system that allowed a unit to default to full astern or full ahead in case of emergency or feedback error. If a system had such an ability, it would be better to default to shutting off so the crew to drop the anchor? I’d be surprised that a classification society would allow such a default built into an approved system? Just shut the dang thing off instead of default full astern? As for this incident, it is obvious to me the vessel was going astern at an uncontrolled speed just as the Research Ship Manawanui was going ahead at an uncontrolled speed. But the Manawanui wasn’t going full ahead due to a default.
…….but outright incompetence.
Fixed it for you!
Good Morning.
Thanks Bugge , that is the Auto Chief system that I was talking about although the unit pictured is a more modern unit than the one I was thinking about. The one I was thinking about is a more clunky affair with a T shaped handle that clunks into the desired engine order D Slow, Slow etc. The T handle can then be rotated to align fore and aft to give other revs other than the designated ones for the set speeds. A very good system.
I worked many Offshore Vessels with CPP before becoming a pilot and yes the default to full astern was definitely a thing although there was better thinking in later builds that made the default full ahead or stop.
Now we have a definite answer about the STS being CPP a default to full astern on a 1980’ s built vessel is a distinct possibility and unfortunately a probable cause for this accident.
In my experience a fault with the CPP system was very very rare, in fact I can only remember it during one period on a AHTS where the emergency stop on the engine has to be operated. This probably happened 2 or 3 times until our engineers diagnosed and fixed the problem.
Me personally it happened when underway causing the vessel to make an abrupt rotation when the Port engine went full astern. The off course alarm was the only alarm to sound as we were in auto pilot but of course that was followed by loud vibration that prompted me to shut down the Port Engine. No harm done as we were in open waters.
Have noticed Dr. Sal concentration and huge effort when He closed eyes longer then 
while blinking. Like heavy lifter lifting 200kg or a man sitting on the toilet bowl and having constipation .
Normally He blinks happily like a Newly wedded girl .
But his last was trully magnificent 
I will check the class rules regarding this default set up as it seems a bit odd to me . Why FUAST instead of DSAST? there must be some reason/ explanation for that.
Just watched the Sal video.
Pretty much nailed it as far as the information we have available at this time.
The plan with the single tug looks like a good one, fast on the starboard quarter then let go to push the bow around. The only other thing I can think of that would have been better was not to let go the tug but have it pull on it’s line to swing the ship. Against this was of course the pivot point being down aft so more force is required. Also perhaps Jug can comment on the size of the bollards on board the STS and if they were suitable for exerting force on.
Just one more question.
If the plan involved the tug pushing on the starboard shoulder why was there not a tarpaulin rigged there to protect the hull .
All said of course with 100% hindsight
