How fault tolerant can a yacht be?

Danny Jo

Danny Jo

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Having striven over the years to make Danny Jo's systems fault tolerant, the recent failure of a seacock handle made me wonder how far one can take this process. Is it possible, within acceptable cost and space limits, to have backups or fallbacks for everything that might fail?

Yes, in this case there was a Mole wrench on board to close the sea cock without its handle, there was a set of wooden plugs at hand to block the hole had seacock failed completely, and there was a liferaft on board (albeit 6 months past its service date). And I guess I'm no different from most recreational sailors in carrying backups to the GPS receiver and depth sounder (aka lead line), as well as spares for the impeller, alternator belt, etc.

What else should there be on the list of critical systems?
 
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Crikey ! A can of interesting worms. :D

I'd start with the idea of MTBF - mean time between failures. Every component has a useful life span, when it can be expected to perform to 100% service. In safety engineering terms, you replace the component at some agreed interval, whether it's 50% , 90% or whatever, or the expected life span. That figure is down to you to ensure a reliable maintenance profile.

Then you need your in-service replacement kit; alternator belts, nav light bulbs, oil filters, water and drain tubing, impellers....

And finally, emergency kit which can be used to sustain floatability in case something breaks, e.g wooden bungs, underwater epoxy, amalagamating tape...

Perhaps the start is to complete a configuration management database for the boat, listing all the components which need maintenance or servicing, with the location (for people unfamiliar with the layout), date of last renewal, part numbers, date of required renewal, supplier name and address, etc.

We have two files on board, with all the instructions and manuals, together with annotations, e.g. alternative manufacturers for oil filters. There should be a copy ashore but :o.

Using your CMDB, you can set up an 'out of season' replacement schedule, and a 'mid-season' list too. In this way , you can balance the cost of preventive maintenance against emergency repairs - though nothing will prevent a genuinely unpredictable and unforeseeable accident.
 
100% if you have the time, money and inclination.

Sarabande - you took me back to a previous life with your description: Maintenance Engineer. The arguments over P10, P50 and P90, levelling, campaign, resource allocation, RCM, JIT, FBM, PMS, PPM and the best of all "Touch F&^k All" by a very Snr Manager.

Danny Jo - best to go sailing and not worry about it but keep a working dinghy or liferaft handy just in case.
 
The Pardeys' books (aimed at global cruising rather than coastal sailing) talk about making a boat "unstoppable". The aim is that, no matter what breaks, you should never be stuck in any port at the mercy of mechanics or parts deliveries. Short of major hull or rig damage, the idea is that you should always be able to set off to another destination - no piece of equipment should be so vital that you can't live without it.

The biggest part of achieving this is minimising interdependence between systems. Indeed, "systems" at all seems to be something of a dirty word to this couple - as far as possible everything is self-contained. Until recently they had no on-board electrical system - the handful of electrical items each ran off their own batteries, and everything else was either manual or powered by paraffin (from a plumbed-in tap for easily filling lamps, rinsing brushes, etc). Thus any one thing going wrong couldn't knock out other things. As opposed to their description of the opposite:
pardey.png


Perhaps not directly relevant to coastal cruising in Europe, but an interesting state of mind from which to start.

Pete
 
Danny Jo said:
Having striven over the years to make Danny Jo's systems fault tolerant, the recent failure of a seacock handle made me wonder how far one can take this process. Is it possible, within acceptable cost and space limits, to have backups or fallbacks for everything that might fail?

Yes, in this case there was a Mole wrench on board to close the sea cock without its handle, there was a set of wooden plugs at hand to block the hole had seacock failed completely, and there was a liferaft on board (albeit 6 months past its service date). And I guess I'm no different from most recreational sailors in carrying backups to the GPS receiver and depth sounder (aka lead line), as well as spares for the impeller, alternator belt, etc.

What else should there be on the list of critical systems?
Click to expand...

I am a neophyte in terms technical....

It is impossible to be fault free... if you try to cover every possible fault then you will end up with a mass of complexity and stuff that will be overwhelming.. and more faults.

So I think the answer is KISS.. try to reduce the possibilities of faults by keeping things as simple as possible. Less is more. In reality there are very few things you need to be able to go coastal sailing.

Critical systems for UK sailing? Keep the boat afloat, the sails up, have a compass, a watch, and a chart.
 
sarabande said:
Crikey ! A can of interesting worms. :D

I'd start with the idea of MTBF - mean time between failures. Every component has a useful life span, when it can be expected to perform to 100% service. In safety engineering terms, you replace the component at some agreed interval, whether it's 50% , 90% or whatever, or the expected life span. That figure is down to you to ensure a reliable maintenance profile.

Then you need your in-service replacement kit; alternator belts, nav light bulbs, oil filters, water and drain tubing, impellers....

And finally, emergency kit which can be used to sustain floatability in case something breaks, e.g wooden bungs, underwater epoxy, amalagamating tape...

Perhaps the start is to complete a configuration management database for the boat, listing all the components which need maintenance or servicing, with the location (for people unfamiliar with the layout), date of last renewal, part numbers, date of required renewal, supplier name and address, etc.

We have two files on board, with all the instructions and manuals, together with annotations, e.g. alternative manufacturers for oil filters. There should be a copy ashore but :o.

Using your CMDB, you can set up an 'out of season' replacement schedule, and a 'mid-season' list too. In this way , you can balance the cost of preventive maintenance against emergency repairs - though nothing will prevent a genuinely unpredictable and unforeseeable accident.
Click to expand...

BlowingOldBoots said:
100% if you have the time, money and inclination.

Sarabande - you took me back to a previous life with your description: Maintenance Engineer. The arguments over P10, P50 and P90, levelling, campaign, resource allocation, RCM, JIT, FBM, PMS, PPM and the best of all "Touch F&^k All" by a very Snr Manager.

Danny Jo - best to go sailing and not worry about it but keep a working dinghy or liferaft handy just in case.
Click to expand...

Yes it took me back too, I was involved in developing an EKPM (equipment key performance measures) many years ago.

Based the maintenance program used for the F-1-11 fighter jets, only took to 3 months to get it off the ground then another 9 months to fine tine it, it's still in use today and saving millions of dollars in Ozzie mines and ship loading ports.

I have to confess I still use it to some degree on the boat and have several large data files on my standby computer the 'crappy lappy' on board.

We also developed a code system to describe common faults and failures, to this day an old friend who used the system still uses the codes when we speak on the phone or two way.

Great days. thanks for the reminder.

Avagoodweekend......:)
 
photodog said:
LUXURY!
Click to expand...
When the headlinings are down, the sole boards are up and wires are everywhere, one of my crew delights in taunting me with an oft-repeated account of his visit to a magnificent replica of a classic yacht. No radio, no engine, nothing electric.
 
Doesn't it depend on how fault-tolerant the skipper is?

Some people will not leave port unless everything is working, others will be content as long as safety-critical stuff is OK.

The trouble is, given the wrong circumstances all sorts of things could turn out to be safety-critical.
 
Fault Tolerance

You need to divide your concerns for the boat into 2 areas. One is when the boat is left on a mooring with out any occupant.
Here your concerns become that of coming adrift and of sinking perhaps of fire or even intruders.
It is fairly easy to provide multiple load paths for mooring (except for swivel shackle on a swing mooring)
Regular maintenance and inspection are vital here.
Sinking Regular inspection and maintenance is all you can do for hull openings sea cocks etc. Water barriers/ partitions may keep any flooding to a localised area. Of course a auto bilge pump will help to a degree. Any further security might require an alarm system.
Intruders are always a worry. Stout locks and washboards are first defence followed by an alarm system.

Then you set off sailing. The basic essentials of the boat are the rig the hull and steering. Replacement of rigging wire at 15 years or so is essential as a maintenance program. Inspection of all other components of the rig are vital. The hull hopefully has been covered by above.
Steering likewise should be inspected. some degree of redundancy can be provided by spare tiller and or provision for steering oar or other rudder replacement.
You may consider the engine serviceability vital. In which case you are into a whole area of maintenance
Possibly redundancy of fuel system (filters). Certainly a redundancy of batteries for starting.
Lastly you may consider electrics and electronics vital. here redundancy is easier and more obvious.

In the end I think maintenance is better than redundancy as a defence. Of course safety equipment is vital.
Unfortunately it is probably human error and the elements that bring you down. Not so much gear failure provided it has been cared for.
it is all up to you. There are some reasonable standards that most people comply with. However your own concerns will be ultimate decider on what you do to make your boat fault tolerant.
good luck olewill
 
William_H said:
In the end I think maintenance is better than redundancy as a defence.
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I think this is the nub of the issue.

What bugs me about redundancy, back-ups and fall-backs in systems, safety procedures and emergency equipment is the complacency it encourages. You know the sort of thing: "This stymieslider is a bit dodgy, but not to worry, there's another one in a box somewhere". If only - but you took that box off last winter and it's still in the garage. Or: "I can't get my head round how to get the **** out of this diesel tank, so let's just back up the primary fuel filter instead."

A key enhancement to preventative maintenance as the first of line of defence is the ability to carry out troubleshooting maintenance while at sea. When I first got Danny Jo, I did what every other proud new owner does and poked around in every corner. What I saw scared me - how on earth does this shaft seal keep the water out? What would I do if there was an electrical fault - I'm way out of my depth in this lot. But I soon discovered that one of the big benefits of owning an older boat is that she forces you to confront each system or bit of gear and learn how to fix it, or failing that, replace it. In the process you acquire much of the confidence and some of the knowledge required to troubleshoot problems arising at sea.

Responses to this thread have helped me crystallize my approach to maintenance and backup. I guess readers might argue this doesn't need crystallizing - it's common sense. Yes, maybe, but I think that formalizing it helps set priorities, reduces waste in time and money and lays a foundation for a check list of essential equipment or tasks.

Systems may be divided into four broad categories, each requiring a different approach (in priority order within each group):

1. Essential for reaching safety in the event of mishap
a hull capable of staying afloat and upright;
a means of propulsion;
a means of steering (if not provided by the means of propulsion);
a compass (pace John Masefield and his star for steering his tall ship);
a course to steer.

This list assumes a preference for reaching safety unaided. But a recent "Learning Curve" in YBW indicates that some yachties opt for the alternative strategy of relying on external assistance, for which one needs a means of staying afloat, an approximate position and a wireless communication device.

Items or systems in this category must be well-maintained at all times, although they are important enough to justify keeping back-up devices such as emergency tiller, emergency rudder blade, auxillary engine and life raft on board. In addition, they must be protected against unfavourable events such as fire and water ingress, and backed up by a strategy for dealing with catastrophic failure of the hull

2. Aids to communication and safe navigation
record of recent position that is independent of ship's power supply;
paper charts (even if a chartplotter is the primary means of navigation);
depth sounder;
GPS or other device for position fixing;
radar transponder or effective radar reflector;
navigation lights;
speed and distance log;
VHF radio;
source of electrical power as required by above.

Items in this group are candidates for the redundancy approach (i.e. you either have a backup system, or you simply accept that can manage without the item). Arguably paper charts should be in group 1, and failure to update them might conceivably have damaging consequences, but so long as we know our approximate position, most of us could choose a course to steer to bring us within sight of recognizable land (English East Coast sailors excepted).

3. Aids to crew survival and well-being
fresh water;
lifelines, harnesses and jackstays;
MOB recovery equipment and procedures;
lifejackets;
wet- and cold-weather clothing;
remedy for seasickness;
food.

While it is imprudent to leave port without these items, and their absence or failure might result in fatality, only fresh water, perhaps, is absolutely essential for returning a coastal-waters yacht and her crew to land.

4. Luxuries
bunks;
navtex;
AIS receiver;
radar;
wind speed and direction indicator;
autopilot;
chartplotter.

Except in the case of bunks, backups for devices in this group are not usually carried
 
I agree with keeping a log of failures and when you bought the kit. We apply service packs a month before the failure period calculated from the log. Usually works.

On the seacock front handles often break, the solution is change over to Marelon seacocks which we have.

The other thing is try to avoid boaty kit if you can get an industrial pump, fridge, watermaker or whatever it will last much much longer. Boaty kit is not designed for heavy useage.
 
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