Electric magnetic field heath problems and sea sickness

[StuM]

Originally Posted by Ralsy

Apologies given, as this post is based not on a sailing boat but on a powered cruiser, but I think the topic is still relative to both.
Electric magnetic field heath problems and sea sickness
In alot of boats, passengers sit very close to electrical systems (such as batteries) of significant power, usually for a considerable amount of time. Apparently the currents achieved in these systems and the short distances between the power devices and the passengers mean that the latter could be exposed to relevant magnetic fields. In my case approx 1000 amp 12v battery bank underneath the main cabins bed, around 12 inches below the bottom of the mattress.

You mean a 1000 Amp hour battery bank. The bank size is irrelevant.


The only thing relevant is the actual current flowing. Which will be just a few Amps for the vast majority of the time and will very rarely go above about 100 Amps for more than a few minutes when using winches, heavy draw items through an inverter etc.


The DC magnetic field generated by a few Amps @ 12V is negligible and its strength reduced with distance according to the inverse square law. i.e. it's strength at 12 inches is only 1/144th of its strength at one inch.

[Ralsy]

Originally Posted by StuM

You mean a 1000 Amp hour battery bank. The bank size is irrelevant.


The only thing relevant is the actual current flowing. Which will be just a few Amps for the vast majority of the time and will very rarely go above about 100 Amps for more than a few minutes when using winches, heavy draw items through an inverter etc.


The DC magnetic field generated by a few Amps @ 12V is negligible and its strength reduced with distance according to the inverse square law. i.e. it's strength at 12 inches is only 1/144th of its strength at one inch.

Thanks for the information. It's reassuring to know that it's ok.

[GeneM]

I agree that radiation is not a concern. You have to get up into the x-ray category to begin concerns with ionizing radiation that makes you sick.

DC makes hardly no radiation, since it is not oscillating. AC generates some radiation, but it's harmless.

Over decades of working on ships and boats, I found that you build tolerance for motion sickness. It happens slowly as you stop being focused on it and relax.

[AlanR]

There is no such thing as a 1000 Amp battery. I expect it is a 1000 Amp Hour battery. That means it can deliver 1 Amp for 1000 hours, 2 Amps for 500 hours, etc. Except for starting the engine, the normal current it is supplying will only be a small fraction of 1000 Amps. And of course your starter motor only runs for a few seconds at a time.

It's a analogous to saying "I have a 50 Gallon motor car; is that dangerous?" Ampere Hours describe the capacity of the battey, how much charge it can hold, just like Gallons describe the capacity of your fuel tank.


No electromagnetic radiation from DC, so,the biggest risk is from the gasses emitted from the battery, but providing the battery compartment is properly vented, it will be safe.

Not so the stability of the boat. With these constraints, I would walk away, quickly. I'm serious about that.

[Stewie12]

Naiad stabilizers are very effective and I have sailed thousands of miles with them in a 65 Sea Ranger, which has the same sea handling capabilities as a brick. Of course there are some people who get sea sick the moment the boat is untied from the dock, so I would not let the old owners comments worry me.

[Martkimwat]

Originally Posted by SVHarmonie

55 feet and 45 tonnes? Awwww, come on. I don’t think so! That’s 900,000 lbs!

Let’s do some quick calculations here:

55 ft * 15 feet * 0.75 (prismatic coefficient) gives us a water plane area of about 619 sq feet. So each foot of immersion would displace 619 cubic feet. At 64 lbs/cu foot, that’s 39,400 lbs. JUST to float the boat would have to draw 900,000/39,400 = 22 Feet. No wonder it has “stability issues.”

You don’t need to pull the sharpest pencil from the box to know this is BS.

If I wanted to troll the forum, my post would look an awful lot like this one...

I haven't checked you maths in detail but I think you have made an error somewhere. 55 tonnes (metric tons) is equal to 55 cu.M of fresh water. the boat is 16.5M long x 4.5M wide. Assume for the moment a rectangular barge, that's 74.25 Sq M, so even if you allowed that to be reduced by about 30% for the pointy ends,(51.975 Sq.M) it's still a little over a metre draft. 55/51.975 = 1.058M

[alansmith]

People with pace makers are the only ones I know of that have to be careful around magnetic devices. But that is more related to use of motors, like a power saw on 110 ac. The pace maker has a battery and a computer inserted under the skin and muscle near the left clavicle. The programming can easily be disturbed by using a chop saw, heavy router, etc.

I know this from personal experience and anyone with a pace maker is carefully informed of this phenomenon. My father borrowed my chop saw for a closet job installing an aromatic wood. After doing hundreds of cuts over two days he asked me why he kept getting dizzy. OMG ! I had forgotten my college physics class magnetic fields produced by electrical motors.

Another thing: Tesla has up to three motors that sit under your feet. Humungus battery banks that draw ungodly amounts of amps to move their cars at frightening acceleration curves. No one gets whacked with magnetic fields afaik.

[Hoodsail]

Who gets to sleep 8 hours, especially when underway?

[waterman46]

Watch out for UFO's, they can be a problem too.

[captlloyd]

At that length and beam I find it hard to believe that this steel boat would be that unstable. The steel boat I built was 64ftx17 ft. beam and I asked the designer, George Sutton, if it would be safe to launch without ballast or machinery. He said no problem. It did bob around like a cork.

[a64pilot]

Originally Posted by GeneM

I agree that radiation is not a concern. You have to get up into the x-ray category to begin concerns with ionizing radiation that makes you sick.

DC makes hardly no radiation, since it is not oscillating. AC generates some radiation, but it's harmless.

Maybe,
There was a study that got squelched quite quickly about AH-64 pilots and brain tumors. The helmet we wore had very high voltage IR receivers right up against our head and we had a cathode ray tube strapped to the right side of our face, there was significant RF, and the incidence of brain tumors over the general population was exceedingly high.
As Stu said distance is extremely relative.
I used to sleep in a water bed, the last one I purchased a low voltage DC heater as it’s RF is very low, but it’s one reason why I won’t sleep under a 110V electric blanket.
Not saying an electric blanket or a water bed heater will necessarily harm you, but why put yourself in that RF field unnecessarily?

[Jim Cate]

[QUOTE]Not saying an electric blanket or a water bed heater will necessarily harm you, but why put yourself in that RF field unnecessarily?[/QUOTE

Umm, mate, 60 hz is hardly RF...

Jim

[Ralsy]

Originally Posted by waterman46

Watch out for UFO's, they can be a problem too.

NO, I've always dreamed about being picked up by aliens and taken to their planet. Bring it on.

[hamburking]

If you are truly concerned with EMF, why not get a sailboat with no batteries at all. I sailed a C&C25 with pretty much no electrical system...I removed it! Handheld VHF, handheld GPS, handheld compass, and lots of flashlights. There actually was a battery...for the running lights mostly, located well aft, away from the cabin, and well below the cockpit. Outboard engine with pull start.

I have no fear of electricity or magnetic flux on a boat...I just like a simple boat. When a dirty carb stopped my outboard (classic honda 100 problem), I sailed with no engine...what a delight, so quiet!!! (FWIW, I sailed out of Portsmouth Olympic Harbour on Lake Ontario, with 2 small kids).

Your real concern should be the alarm clock next to your bed at home, and your cell phone/charger.

[barnakiel]

Provided the boat is big enough, her EMF fields could potential affect your health. Think of USS Zumvalt and similar craft.


Furthermore, it is very bad to stand close and in line with a radiating radar antenna. It is just as dangerous to hold on to an emitting SSB antena while operating an internal pacemaker.


But I have never heard of any relationship of emf and sea-sickness.


b.