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Old 11-01-2018, 20:43   #1
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High-availability electrical systems for safety

A common theme among accidents on passage is loss of electrical power.

With a large, capable crew, it doesn't matter as much. You can bail with a bucket or work a manual bilge pump. You can hand steer. You can navigate with a handheld GPS, or a sextant if it comes to that. You can get by with less water and no refrigeration. Making landfall, you can sail where you would prefer to motor, and set anchor without the windlass.

But an average crew of one or two cannot do all those things at once, especially on boats that were once considered large, especially not in a storm. They depend on the electrical systems.

So many accidents involve a shorthanded crew, overwhelmed by a series of problems, one of which is the loss of electrical power.

It seems to me that the most basic shortcoming of the boats, in that light, is simply one of insufficient battery capacity. I take the lesson that more batteries buy you time. They buy you time for the pumps to run until the storm passes and dawn breaks. They buy you time to run the autopilot when you're exhausted, the weather's down, and something's happened to the engine. They buy you time, so you can deal with problems in calmer weather, in daylight.

Once in a while, batteries alone won't help, either because the batteries themselves are part of the problem, or because there are difficult-to-find problems in the electrical distribution system. I'm surprised that split-bus systems aren't more widely used. They are not uncommon on aircraft. The basic idea is two separate electrical systems for redundancy, with critical loads split across them, usually with some provision for connecting the two systems together when everything is working properly. As an example you'd have an "A" bus with the main autopilot, one of the bilge pumps, the nav desk chartplotter, and then the "B" bus with the backup autopilot, the helm chartplotter, and another bilge pump.

Split bus systems add complexity but in the greater scheme of things aren't that expensive. It's really just a matter of separating out the redundant equipment already on board across two buses.

Thoughts?
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Old 11-01-2018, 20:49   #2
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Re: High-availability electrical systems for safety

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Originally Posted by Jammer View Post
A common theme among accidents on passage is loss of electrical power.

.....?
Do you have examples of this theme? I can't think of a single cruising boat that was lost or near lost over the time we've been cruising that was caused by a loss of electric.

Setting up a separate battery that is significantly above the waterline and can be switched in for emergency communications gear is certainly doable. Just not commonly done on offshore cruising boats.
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Old 11-01-2018, 20:54   #3
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Re: High-availability electrical systems for safety

Aground at Elbow Cay

Also was one of the major contributing factors in the loss of the Rebel Heart, though the discussions usually focus on other things that went wrong.

Even if the main cause of the loss of a boat is elsewhere, I believe there are many accidents that could have been prevented if electrical power had been available.
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Old 11-01-2018, 21:00   #4
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Re: High-availability electrical systems for safety

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Aground at Elbow Cay

Also was one of the major contributing factors in the loss of the Rebel Heart, though the discussions usually focus on other things that went wrong.

Even if the main cause of the loss of a boat is elsewhere, I believe there are many accidents that could have been prevented if electrical power had been available.
The Elbow Cay wreck had a loss of engine power. The boat still has two large solar panels onboard. So I can't see how any root cause could be attributed to the loss of electric power.

As far Rebel Heart, that is, as you know, a complicated situation. Lots of battery power would not have changed the outcome nor cured the child illness onboard.
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Old 12-01-2018, 09:30   #5
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Re: High-availability electrical systems for safety

emergency electrical supply seems important if you do more than short trips near shore.

FCC Part One requires a Reserve Power source for the radios for even the small inspected passenger vessels, and GMDSS (for 300 tons or >12 passengers) requires both an emergency generator and a reserve battery for radios.

There was a discussion on CF not too long ago about fitting a reserve battery near the radio in the wheel house with an echo charger.

split bus makes sense too, but I don't think I've ever seen one on a pleasure craft.
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Old 12-01-2018, 10:42   #6
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Re: High-availability electrical systems for safety

Multiple, independent charging sources. Eliminate single point of total failure.

Examples: Multiple charge controllers and voltage regulators as opposed to one "does it all" regulator. Each charging source should be independent of other charging sources.

Good battery monitoring, Make battery status part of your normal change of watch routine.

Inspections. Check your major wiring for corrosion. Check for loose wiring. Check water levels. Do it regularly.

Construction. Don't scrimp on wire sizing or quality of components. Solid attachments. Batteries need to be secure, not able to move - not even a little bit.
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Old 12-01-2018, 10:52   #7
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Re: High-availability electrical systems for safety

In an inspected/commercial vessel, an emergency supply and automatic switch over would not be out-of-place. At some point redudant busses would make sense, but that sounds like overkill even from my techy mindset.

I did put together the architecture in the attached diagram. The circuittry still needs some polishing, but it does give redundant power sources for the critical bridge equipment. It doesn't split the critical equipment onto multiple busses, and is thus still open to a single fault taking out everything. But it will survive loss of the house batteries and everything below decks.


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Old 12-01-2018, 12:35   #8
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Re: High-availability electrical systems for safety

Some what common on larger commercial vessels (and sometimes required depending on how the vessel is classed). At work we have built a few panels to handle things like this for the occasional recreational vessel ( the one I can think of was a 60' steel trawler) but as said not common.
I know of one we built where we used Schottky Diodes to provide an immediate back up from a power supply to a battery (this boat was large enough that AC power was available most of the time) but an on-on switch could work as well.
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Old 12-01-2018, 14:19   #9
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Re: High-availability electrical systems for safety

Quote:
Originally Posted by Jammer View Post
A common theme among accidents on passage is loss of electrical power.

So many accidents involve a shorthanded crew, overwhelmed by a series of problems, one of which is the loss of electrical power.

It seems to me that the most basic shortcoming of the boats, in that light, is simply one of insufficient battery capacity.

Thoughts?
My initial reaction, allowing for the inevitable exception, is that one should never lose a boat due to a loss of electrical power. It astounds me that one's seamanship and decision making would be so poor as to cause the loss of a vessel simply because the electrical power died.

Having said this, there are a few caveats. First, the boat that loses an engine at the worst possible time, with no time to correct, is just one or those things. An accident. Sometimes bad luck happens.

Most often I see people depend upon electrical systems, e.g. a chart plotter and allow no room for error. They assume that the chart plotter, or worse, the chart plotter tied into the auto pilot, will safely get them where they are going.

If you are in a sketchy situation, you should be manually steering. If you are not confident navigating without a chart plotter, and have no situational awareness, then perhaps you should not be attempting the passage. Actually remove the word perhaps.

I see this all the time. People assume that the chart plotter is accurate, that the GPS is providing a correct signal, that the electrical system will not fail, that the chart is accurate, etc. Remember Murphy's law; if it can fail it will, and usually at the worst possible time.

There is no reason other than a true emergency where one needs to put themselves, others, and the vessel at risk. If one is not confident without electrical equipment, then heave to off shore and wait until conditions are better. As for TRUE emergencies, those are few and far between. Uncontrolled bleeding is a true emergency. Anaphylaxis is a true emergency. Interestingly, a cardiac arrest is NOT a true emergency, since clinically they are already dead. In a true emergency then you may need to put the vessel at risk, but again, these situations are few and far between.

One should always have a back up plan and be prepared to sail with no electronics or electrical systems.
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Old 12-01-2018, 16:02   #10
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Re: High-availability electrical systems for safety

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My initial reaction, allowing for the inevitable exception, is that one should never lose a boat due to a loss of electrical power. It astounds me that one's seamanship and decision making would be so poor as to cause the loss of a vessel simply because the electrical power died.
...
One should always have a back up plan and be prepared to sail with no electronics or electrical systems.
I would agree that one should never lose a boat solely due to a loss of electrical power.

On the other hand it is possible to lose a boat, for a combination of reasons, that would not have been lost but for the loss of electrical power, since having comms, pumps, lights, and an autopilot all make it easier to deal with, well, whatever.

Can you hand steer and run the manual bilge pump for a watch? Can your crew? In the dark, in a storm? How long can you keep it up?
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Old 14-01-2018, 10:34   #11
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Re: High-availability electrical systems for safety

Ship certification typically requires both emergency power from an emergency generator or a large battery bank capable of supplying emergency lighting, helm power, steering power, engine pumps, bilge pumps, etc. for 24 hours, along with a transitional emergency system that covers the amount of time required to bring the emergency system online.

They may or may not have a seperate distribution system as the OP describes, to the equipment.

Small boats obviously don't have this due to cost, weight, etc.

But that doesn't mean it would be unwise, contrary to several posters.
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