Donks, Donkeys and Sheep.
Sheep first. The Sheep climb inboard everyday; oblivious to questionable welding; skinny design, dubious capability in high seas; unreliable steering; engines being run to max all day everyday and failing (spectacularly); repairs deferred; deflected Safety Management System; cooperative governance, useless OTSI; toothless AMSA; etc. The messaging is as simple as this:- DO NOT travel on theses things; vote with your Opal card; boycott 'em; watch the changes happen.
Now then, “Donk” is an affectionate term for what are some superb power units designed for aviation use. Even 'Superb' is an understatement; they are remarkable engineering marvels (most of 'em anyway). The term derives from the donkey's pulling the cart; and they do this remarkably well.
Now, robust as they are 'donks' are designed and built to perform reliably within certain clearly defined parameters. The best educational tool for learning to understand the 'limitations' of machinery is the humble baked bean can lid. They can take a hellish pounding when attached to the can (we've all been without the can opener and tried) but detach it and it looses integrity; fold it over in half three or four times each way and see what happens; it will break. Metal has a 'memory' and it 'keeps count' of of every over design stress imposed; when it reaches the 'limit' it simply quits. Depending on where the over stressed/ heated component is located and its design function; the results may vary from minor inconvenience to major, catastrophic, even to dangerous failure of other components.
Those with knowledge of the reciprocating engine may ignore the following 'simple'. But I wonder how many passengers of the Ferries today actually understand what has happened on the 'Clontarf' and what could have happened. So forgive the very rudimentary explanation of why it was so very dangerous.
![[Image: d875542e610613ca6fa6879fb92a8e36.jpg]](https://i.pinimg.com/originals/d8/75/54/d875542e610613ca6fa6879fb92a8e36.jpg)
Lets begin with 'the piston'. I have a small one from an aircraft engine on my desk, it is very battered; diameter about 100 mm; 90 mm deep and weights probably about 1.2 Kg. Cleverly designed for efficiency and, very dependent of a 'tight' fit within the barrel of the cylinder; it has grooves around its circumference to accommodate the 'rings' which prevent oil for coming up and provide a 'gas tight' fit to ensure maximum 'bang for your buck'. Travelling at high speed into a compressive gas; a spark ignites the fuel and the hot, violent hammer blow of combustion drives it out of the compression area. The thing which returns our piston to the 'bang' site is the crankshaft; the connection between the two made by a connecting rod; or 'con-rod. Within each cylinder there is a very precise, tight order in which events happen; there is great force, great heat and great energy – all dangerous if not carefully managed and contained. The real dangers in the 'Clontarf' engine failure are two fold. The con-rod separated from the piston. While the engine was running; this one long piece of very tough metal could (and did) have knocked a large lump off the engine side; now there is oil, combustion, excess heat and un-burned fuel in the mix. The explosive forces within that engine, at that time, were 'significant' to the point of life threatening. Make no mistake about that. Was there an automatic 'kill' system which instantly stopped the engine; shut off the fuel and contained the oil? No; well there bloody well should be. Are there engine health displays in the wheel house with alarms and a big red stop button? No? Well repeat the above.
This ain't like the Falcon quitting on Friday night. For those not 'technically' minded or even interested; Let me (as Wombat say's) put that another way. Think of a heavily loaded donkey cart; pulling a huge load; in hot dusty conditions; being unmercifully whipped by the driver – until it drops dead by the roadside. Beautiful Yanmar engines being brutalised every day – until they quit. Rightfully so IMO. Quitting is OK; but exploding while doing so? That is just a little too risky for me. Aircraft engines run for thousands of reliable hours – why: well - just think about it (and the consequences). If you were off to the Barrier Reef for a holiday and the left engine blew up mid flight – what then Sheep? What then?
![[Image: single-frothy-pint-beer-burning-600w-483277990.jpg]](https://image.shutterstock.com/image-photo/single-frothy-pint-beer-burning-600w-483277990.jpg)
Sheep first. The Sheep climb inboard everyday; oblivious to questionable welding; skinny design, dubious capability in high seas; unreliable steering; engines being run to max all day everyday and failing (spectacularly); repairs deferred; deflected Safety Management System; cooperative governance, useless OTSI; toothless AMSA; etc. The messaging is as simple as this:- DO NOT travel on theses things; vote with your Opal card; boycott 'em; watch the changes happen.
Now then, “Donk” is an affectionate term for what are some superb power units designed for aviation use. Even 'Superb' is an understatement; they are remarkable engineering marvels (most of 'em anyway). The term derives from the donkey's pulling the cart; and they do this remarkably well.
Now, robust as they are 'donks' are designed and built to perform reliably within certain clearly defined parameters. The best educational tool for learning to understand the 'limitations' of machinery is the humble baked bean can lid. They can take a hellish pounding when attached to the can (we've all been without the can opener and tried) but detach it and it looses integrity; fold it over in half three or four times each way and see what happens; it will break. Metal has a 'memory' and it 'keeps count' of of every over design stress imposed; when it reaches the 'limit' it simply quits. Depending on where the over stressed/ heated component is located and its design function; the results may vary from minor inconvenience to major, catastrophic, even to dangerous failure of other components.
Those with knowledge of the reciprocating engine may ignore the following 'simple'. But I wonder how many passengers of the Ferries today actually understand what has happened on the 'Clontarf' and what could have happened. So forgive the very rudimentary explanation of why it was so very dangerous.
Lets begin with 'the piston'. I have a small one from an aircraft engine on my desk, it is very battered; diameter about 100 mm; 90 mm deep and weights probably about 1.2 Kg. Cleverly designed for efficiency and, very dependent of a 'tight' fit within the barrel of the cylinder; it has grooves around its circumference to accommodate the 'rings' which prevent oil for coming up and provide a 'gas tight' fit to ensure maximum 'bang for your buck'. Travelling at high speed into a compressive gas; a spark ignites the fuel and the hot, violent hammer blow of combustion drives it out of the compression area. The thing which returns our piston to the 'bang' site is the crankshaft; the connection between the two made by a connecting rod; or 'con-rod. Within each cylinder there is a very precise, tight order in which events happen; there is great force, great heat and great energy – all dangerous if not carefully managed and contained. The real dangers in the 'Clontarf' engine failure are two fold. The con-rod separated from the piston. While the engine was running; this one long piece of very tough metal could (and did) have knocked a large lump off the engine side; now there is oil, combustion, excess heat and un-burned fuel in the mix. The explosive forces within that engine, at that time, were 'significant' to the point of life threatening. Make no mistake about that. Was there an automatic 'kill' system which instantly stopped the engine; shut off the fuel and contained the oil? No; well there bloody well should be. Are there engine health displays in the wheel house with alarms and a big red stop button? No? Well repeat the above.
This ain't like the Falcon quitting on Friday night. For those not 'technically' minded or even interested; Let me (as Wombat say's) put that another way. Think of a heavily loaded donkey cart; pulling a huge load; in hot dusty conditions; being unmercifully whipped by the driver – until it drops dead by the roadside. Beautiful Yanmar engines being brutalised every day – until they quit. Rightfully so IMO. Quitting is OK; but exploding while doing so? That is just a little too risky for me. Aircraft engines run for thousands of reliable hours – why: well - just think about it (and the consequences). If you were off to the Barrier Reef for a holiday and the left engine blew up mid flight – what then Sheep? What then?