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Old 06-12-2014, 05:21   #46
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Re: Boat fire safety

Originally Posted by Maine Sail View Post
There is an "exemption" for starting motor circuits, they do not advise not doing it. Many professionals, myself included, do fuse cranking conductors when it is possible and it is possble of a large majority of engines out there..

Considering that I have literally hundreds of cranking circuits protected by OCP your statement about it being "useless" is simply flawed. It can be done and is done in ever increasing numbers......

When you get to massive engines it becomes more expensive and more difficult, so a conduit is a good choice. For the vast majority of marine engines out there, including outboards and most any small sailboat aux engine as well as many diesels up into the 350HP range OCP is easily done.

But hey don't just take my word for it...

I quote our good friend Nigel Calder here:

"The net result is that nowadays, electrical shorts are probably the number-one cause of fires on boats."

There is simply no excuse for not protecting all high-current circuits , including the cranking circuit."

Nigel Calder Cruising Handbook

The vast majority of marine engines in the world today can easily be protected with over current protection. If you own a boat with massive engines, please put your starting motor conductors in a protected conduit, if they can not be fused!

This boat was "exempted" and a single group 24 battery caused this..... Is this exemption right when a simple 100A fuse would have protected this boat??? Not in my mind....

What do we know about this fire, on a 15' Boston Whaler?

1- Electrical fire
2- Single Group 24 battery
3- Multiple children under the age of 9 on-board seconds before the fire! (Junior sailing program chase boat)
a. I fused mine.

b. I witnessed a fire that took out 3 parked fuel trucks. The starter wire chafed on the frame, where it happened to pass near a diesel engine fuel line. The fuel siphoned, and despite spending several 20-pound dry chemical extinguishers, nothing could be done. I doubt the arcing current was enough to trip a sufficiently large fuse (3208 Cat).

c. Just yesterday I was investigating the aftermath of a small refinery electrical fire. The root cause? the knuckle head that did the last repair did not properly secure a contactor, resulting in a wire cracking from vibration, which resulted in down stream over load of the remaining phases. Again, over current protection cannot function in all cases. Fortunately, the fire was in a box and self extinguished.

Chafe protection and securing against vibration are both HUGE.
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Old 06-12-2014, 14:05   #47
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For fire fighting a full face mask with the right filter would be a pretty usefull addition keeping smoke from eyes and lungs, and its also very usefull for any sanding and painting work.
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Old 06-12-2014, 15:13   #48
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Re: Boat fire safety

Originally Posted by Wotname View Post
Yep, Tefzel is the "goto" wire choice in aviation and most of us rednecks think "teflon"

FWIW, some details on insulation types are here

No reasons apart from cost and that it usually white or white. Colours are manufactured but are not so commonly available. I think the "stiffness" is due more in part to the insulation rather than the conductors.

It is tinned.
Tefzel is great stuff. I tried burning it once out of curiosity. I expect it would be self extinguishing in most overheating or short circuit fires and it gives off drastically less toxic fumes than PVC.

I don't think it right why it, or something better than PVC isn't used in boats. €$ег of course - we all know life is actually not priceless. PTFE and neoprene are also safer.
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Old 06-12-2014, 15:32   #49
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Wink Re: Boat fire safety

Originally Posted by Dockhead View Post

What I don't have:

1. Smoke alarms.
2. Temp alarm in the engine room.
3. Fire pump (although that's required by regs for my size boat).

Needs to be done.
I'm pretty sure you don't need a fire pump unless coded or unless you have inadequate extinguishers. The requirement is exempted under the MCA pleasure craft rules.
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Old 07-12-2014, 04:39   #50
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Re: Boat Fire Safety

I agree that fusing the starter circuit can be done without nuisance fuse blowing. But I have yet to see any objective testing that shows this does anything to prevent fires. Is anyone aware of any rigorous proof that fusing a starter circuit significantly reduces the potential for a fire?

Chafe is one argument for fusing. But most chafe results in a fairly high resistance connection where the wire is casually touching some grounded metal. To blow a 200A fuse requires a "casual" connection of less than 50E-3 ohms. Not many chafed wires will ever create such a low resistance touching a steel motor frame. I have thought this was the logic of ABYC in not mandating fuses in starting circuits but do not pretend to read their minds.
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Old 07-12-2014, 04:42   #51
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Re: Boat fire safety

Originally Posted by leftbrainstuff View Post
Corrosion from sea water is why not. Aircraft aren't expected to experience sea water based contact like boats are subjected to. Aircraft wiring is not tested or certified for marine use.

That's why the low flying surveillance aircraft have issues. Australia has been battling this problem in our Orions for decades.

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Is there any evidence the problems are related to the wire? I would think silver plated wire would be superior in a marine environment to tin plated or unplated wire. Certainly the insulation in aircraft wire is superior to PVC. But the high cost may not be justified.
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Old 07-12-2014, 06:50   #52
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Re: Boat Fire Safety

Actually, I once had a near-fire experience on my own boat when the starter motor "froze" allowing unlimited current to draw through the 2-0 cable. I couldn't get to the battery switch quickly enough, so I bashed the cable off the battery post with a hammer. The insulation had begun to melt off the positive cable and the bulkhead was scorched. That was a long time ago. After a series of different large fuses I today use a 300 amp, Blue Sea class T fuse located within a foot of the cockpit located battery switch, which is located a foot away from the engine start battery. I also have one just outside the house bank, prior to the selector switch to the inverter. The smell of burning insulation lingers forever in my memory.
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Old 07-12-2014, 10:41   #53

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Re: Boat Fire Safety

Dan, bear in mind that for the first 70? 80? years automobile batteries were not fused. Neither were boat batteries. No one saw a need for it. And then for how many years was it normal to use fusible link wire, instead of an alternator fuse? Now banned as a fire hazard rather than a protective device.

So as to ABYC's logic or logic in general...roll the dice and come back next year to see what changes.

I would suggest that starter motors have been known to short circuit (as the insulation grinds off an overheating and expanding rotor) and starter solenoids have been known to fail (open or closed, your choice) and given the low resistance of the starter circuit, it is feasible that the circuit could fail and create a short with a capacity high enough to start a fire. Unlikely, perhaps, but possible.

Which would make fusing that circuit something easy enough to justify, even if it was not likely to be needed.
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