morse cable failure

[Mike Adams]

My boat, with a hydraulic drive, and the machinery placed at the bow has long morse cables(45') to the engine  and hydraulic gear control lever. Now the gear control could be set up either way so that the cable pushes the control lever for forward or pulls for forward and the opposite for reverse. Over many years on various boats I have only had one morse cable fail and it did so by fracturing and breaking the inner core where it joins the solid threaded end. Thinking about my family borrowing the 62' boat for a trip on the Thames and their experience with things mechanical I was thinking of the best arrangement with the gear cable so that if it were to fail it would do so in reverse and not forward.

My thoughts are that it is more likely to happen when the cable is in tension so that having it push into reverse and pull into forward would be better so that rather than the boat jamming in forward it would at least jam into reverse and far less likely to cause a problem in a lock for example. Other ideas are fitting a spring to reset to reverse if the cable fails.

Any thoughts or experience of this potential problem would be welcome.

[mrsmelly]

We had morse cables on one boat I skippered, they were around 80 feet long and never been replaced in many years, however we had cables running alongside them so in the event of one failing we could quickly change over in a matter of a couple of minutes to the new ones. Just worth a mention so if it does happen they/you can be ready to quickly get going again even if a short call out would be required by such as RCR.

[Tony Brooks]

13 minutes ago, mrsmelly said:

We had morse cables on one boat I skippered, they were around 80 feet long and never been replaced in many years, however we had cables running alongside them so in the event of one failing we could quickly change over in a matter of a couple of minutes to the new ones. Just worth a mention so if it does happen they/you can be ready to quickly get going again even if a short call out would be required by such as RCR.

A very good point.

 

We had a number of forward control boats with transverse engines at the back that also had long cables and they were no more likely to break than the more typical short ons. It is important to ensure any bends in the cables are large.

 

I would have thought that  a cable snapping in reverse would put a narrow boat in an uncontrollable state where as if it fails in ahead there is a small chance of choosing what to hit and at what angle. if by chance it snapped in mid stream failing in ahead gives some choice as t which bank to go to. The bow of a narrow boat normally has  much less draft than the stern so if it comes to a choice you can normally get the front closer to the bank than the stern so another reason for hoping it fails in ahead.

 

If you do not run a spare cable as per @mrsmelly it would be better to work out a system and train the family to work out a system of manual control at the front with spoken/shouted command chain from the stern.

[Mike Adams]

My main concern is going into a lock, behind a Gin Plalace for example and the cable failing they would then go hard astern but in fact would be going fast forward. I guess I will need to train them up but outside a lock they can stop the engine and steer the boat and just use reverse to stop or avoid a collision.

[Tony Brooks]

Gin palaces being GRP tend to give without damage when hit at lock entering speed, especially if you have a nice large bow fender to spread the impact.  The problem comes with high speed collisions that push the hull into the inner lining or if its a point impact. I am still wondering how you can steer accurately enough to avid a collision at lock entering speed and the boat in reverse. I think it will go where it wants to.

[pearley]

Our gear change cable broke last year on exiting lock 3E on the HNC. J had just shut the gate as I reversed back to pick her up. Belted the lock gate and took a chunk of paint from the swan neck.

 

As OP said, broke at joint between cable and solid bit. The outer was at a slight angle at that point do I altered the fixing slightly to give a straighter run. It was 13 years old.

 

A few years ago the throttle cable broke but that was my fault. I tried on it!

[Machpoint005]

5 hours ago, pearley said:

A few years ago the throttle cable broke but that was my fault. I tried on it!

 

and succeeded, apparently!

 

[pearley]

1 hour ago, Machpoint005 said:

 

and succeeded, apparently!

 

Trod!

Should really proof read before pressing submit.

[blackrose]

I think a point to consider in the event of morse cable failure is that the way in which one moves one's boat is a significant factor. For example, one would hope that when going from forward into astern the boat had already been slowed down to the extent that most of the forward momentum had been dissipated and any impact didn't result in a catastrophic collision.  

 

I'm often amazed at the speed that some boaters are going when they decide to slam the gearbox into hard astern. They leave themselves no margin of error and should a cable snap they would be completely fooked! I don't understand why they become so reliant on using high engine revs in forward and astern? Perhaps it's how they drive their cars - hard on the accelerator and hard on the brakes. 

 

It might just be the result of single-handing a big boat, or perhaps it's just my innate mechanical sympathy, but when I'm coming to a stop I slow the boat down well in advance and I tend to knock the gearbox into neutral for a few seconds to see what the boat is doing under its own momentum and I avoid slamming the gearbox into astern. I see far too many boaters using far too many revs to get the boat to do what it will do with much gentler persuasion. 

Edited July 24, 2020 by blackrose

[Mike Adams]

At the moment the morse lever pushes the cable which in turn pushes the control valve into forward so when you pull it back it could stay in forward if it broke. Conversely if I reverse it all, which is not too difficult, by changing the hydraulic pipes around and altering the morse control set up the lever will push for reverse so if it failed it would stay in reverse.

What is the 'normal' set up with a hydraulic gearbox? Does the cable normally push for reverse or not or does it not matter. I still think it would be better to fail stuck in reverse as you are likely to be moving much slower and hence have more control. The assumption throughout all this is that the cable will finaly fail in tension rather than compression but this is only based on the fact that the compressive strength of the cable would be more than the tensile strength.

[ditchcrawler]

10 hours ago, Mike Adams said:

 l I was thinking of the best arrangement with the gear cable so that if it were to fail it would do so in reverse and not forward.

 

Mine did just that in a GU lock and instead of leaving the lock I reversed under the waterfall. The only option was to kill the  engine and push the boat forward with a short shaft.

[Mike Adams]

1 hour ago, ditchcrawler said:

Mine did just that in a GU lock and instead of leaving the lock I reversed under the waterfall. The only option was to kill the  engine and push the boat forward with a short shaft.

Just out of interest does yours 'push' for forward or reverse?

[PhilR]

47 minutes ago, Mike Adams said:

Just out of interest does yours 'push' for forward or reverse?

My current boat  pushes for reverse.

In over 50 years of boating I have never had a morse cable failure, although I did have a control box failure once on the BCN Challenge. We did the next 89 locks with mole wrench and angle brackets on the end of the cable. After about 10 locks I wrapped a sock around the angle bracket for comfort!

We did once have a failure with cable/drum/pulley steering which was highly amusing when we cocked up the repair ........

 

But getting back to Mike's OP, I assume the steering position is close to the engine STOP control? So in the worst case scenario you could stop the engine?

Usually, if it is necessary to use a lot of engine power to get out of a potential collision it displays a lack of forethought and skill. Best to take it easy and be alert.

[ditchcrawler]

1 hour ago, Mike Adams said:

Just out of interest does yours 'push' for forward or reverse?

For forward the  leaver pushes forward (logical) this operates a crank so the cable pulls hydraulic valve actuator, so when the cable detached from the valve it couldn't pull the valve from reverse to neutral.  Which ever way it fails its not fail safe.

[Mike Adams]

25 minutes ago, ditchcrawler said:

r forward the  leaver pushes forward (logical) this operates a crank so the cable pulls hydraulic valve actuator, so when the cable detached from the valve it couldn't pull the valve from reverse to neutral.  Which ever way it fails its not fail safe.

That seems to prove my theory that the cable breaks in tension. If it fails it can be in one of three positions forward, neutral or reverse. No point in it failing in neutral because the same can be achieved by stopping the engine so I would rather have stuck in astern because you are likely to have more momentum going forward which is what you need to get rid in an emergency  so I think I will change mine to pull from reverse. At the moment it is pull from forward.

I accept all the points about taking due care and going slowly  which is fine if you know what you are doing but if you don't have much experience if you go astern and nothing happens then you would tend to put on more power which if stuck in forward would aggravate the situation.(I am leading my pride and joy out to a member of the family hence the examination of all causes of possible problems!)

It would be interesting to know what the normal arrangement is with hydraulic gearboxes.

[WotEver]

If I borrowed a boat where you push the lever forwards to go backwards I’d crash it in the first 10 seconds. Then again every time I set off...

[Awayonmyboat]

It is old, unmaintained and often badly fitted items that fail. Correctly fitted Morse cables have a very long service life/ low failure rate. So my thoughts are as long as you (I) check them to make sure the end fittings are well aligned with what they are operating (and the operation back and forwards doesn't cause then to bend for that is what will weaken then) and (ii) bend radii are all in excess of the minimum you should have little risk of problems. An annual or biannual inspection should then be all that is necessary. If the OP is still worried they could also simply fit new cables now and then stop worrying for a few years (and for belt and braces follow the old dirt bike motorcycle riders trick of leaving the old cables in place alongside the new ones so they are instantly available on the rate event of a failure)

[PhilR]

12 hours ago, WotEver said:

If I borrowed a boat where you push the lever forwards to go backwards I’d crash it in the first 10 seconds. Then again every time I set off...

I agree. But we are discussing whether the CABLE pushes or pulls. I am sure you are aware that gear cables can be attached to control boxes with either direction of travel.

[ditchcrawler]

18 hours ago, Mike Adams said:

That seems to prove my theory that the cable breaks in tension. If it fails it can be in one of three positions forward, neutral or reverse. No point in it failing in neutral because the same can be achieved by stopping the engine so I would rather have stuck in astern because you are likely to have more momentum going forward which is what you need to get rid in an emergency  so I think I will change mine to pull from reverse. At the moment it is pull from forward.

I accept all the points about taking due care and going slowly  which is fine if you know what you are doing but if you don't have much experience if you go astern and nothing happens then you would tend to put on more power which if stuck in forward would aggravate the situation.(I am leading my pride and joy out to a member of the family hence the examination of all causes of possible problems!)

It would be interesting to know what the normal arrangement is with hydraulic gearboxes.

No it failed because the connector on the end came adrift, it could just as easily have failed in forward or neutral  

[bizzard]

I use Meccano bits for things like clevices on the ends of control cables. My boat has them and my car has one on the throttle cable, much better than the so called proper originals.

[mrb2]

I have a 27' narrowboat with a 3 cylinder Yanmar engine operated by a single lever morse control.

I use the boat about 6 or 7 weeks year.

Over the last 5 years the throttle cable has broken 3 times. It's a bloody nuisance and expensive to repair.

Any ideas what the problem is?

[Tracy D'arth]

Cables fail prematurely due to sharp bends or damage to the outer, often caused by touching the exhaust or a moving part.

Often they are badly fitted in haste.

Having the correct length helps to place them with sweeping bends and supported away from damage.