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Old 06-29-2020, 04:51 PM   #1
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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. I'm wondering if the hazards of magnetic field exposure or electromagnetic radiation (EMR) must be taken into account?
Is it usual to put such a large storage of batteries under the bed you potentially spend 1/3 of your day on?
The previous owner of this particular boat has told the broker he doesn't want anything more to do with the boat as all his family members get sea sick on the boat and most other people aswell if they come aboard for any extended lenght of time.
The sea sickness could be enhanced by the relatively narrow beam to length of the boat aswell as the heavy steel superstructure which could make it a little rolley at times. It's a 55ft long, 15ft beam, 45 tonne steel displacement pilothouse cruiser. There is a stability report available on the boat which stipulates the necessary requirements for when cruising such as making sure fresh water tank is full, gray and black are empty, centre fuel tank is empty, the other 4 are balanced except for tank number 1 which needs to have 350 litres of fuel less than tank 4. The boat does have Naiad Stabilizers but still thinking it could potentially be quite rolley.
So there are 2 questions,
1 - could the close proximity of the batteries be a potential health problem OR add to the sea sickness of passengers through the EMF on a steel boat?
2 - could the build of the boat as described be a problem in anything but smooth cruising conditions?
I have been for a sea trial but unfortunately conditions were smooth.
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Old 06-29-2020, 05:20 PM   #2
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So there are 2 questions,
1 - could the close proximity of the batteries be a potential health problem OR add to the sea sickness of passengers through the EMF on a steel boat?
2 - could the build of the boat as described be a problem in anything but smooth cruising conditions?
I have been for a sea trial but unfortunately conditions were smooth.
1. I don't see how proximity to the batteries could have any health impact unless you are breathing charging gasses. Also, batteries do not create electro magnetic fields -- only electrons moving through a circuit do. And those fields are not very powerful (in relative terms) -- If a compass still points north, then the earth's magnetic field is demonstrably more powerful.

2. It does sound like the boat lacks stability (and its narrow beam certainly can't help in that regard). I recommend that you sea trial it.
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Old 06-29-2020, 05:31 PM   #3
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Thanks for your reply.
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Old 06-29-2020, 05:44 PM   #4
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Adhering to all of those tank filling restrictions is not feasible in the real world on a day-to-day cruising basis.
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Old 06-29-2020, 06:20 PM   #5
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Adhering to all of those tank filling restrictions is not feasible in the real world on a day-to-day cruising basis.
Yeah, doesn't sound practicable. Spoke to broker who advised, he'd just fill the tanks and go. Not sure why he wouldn't take on board the recommendations from the stability report. Is it normal for a boat to have a stability report?
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Old 06-29-2020, 06:44 PM   #6
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Re health risks, a battery at rest has no appreciable magnetic field. Once you start pulling current or charging them, there will be a weak magnetic field around the conductors. The field diminishes with the square of the distance.

The particle that carries the electromagnetic force is the photon. A photon's energy is determined by its frequency, i.e. how quickly it moves back and forth. You need to get up into the Giga (Billion) Hertz range (e.g. microwave, radar) or way beyond (e.g. UV light) before you can harm living things. Electromagnetic waves of all frequencies have been all around us since the beginning of time.

Re stability report. Most likely, the stability report just lists the conditions under which the testing or calculation was performed. It does not mean the boat is more or less stable in other configuration. It just was not tested there.
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Old 06-29-2020, 06:47 PM   #7
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I would never want to own a boat that had so many stipulations needed to acheive acceptable stability. What good is a center fuel tank if using it makes the boat unstable ? Was something significan't added to the boat later in life, like a fishing tower or flybridge ?
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Old 06-29-2020, 06:56 PM   #8
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Here are a few pages on this boats operating procedures.
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Old 06-29-2020, 07:02 PM   #9
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There are a lot of people with pacemakers living on boats suffering no ill affects.
Maybe the owners friends get sea sick very easily.
If you are that worried about it, start looking at other boats or consider a RV.
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Old 06-29-2020, 07:09 PM   #10
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There are a lot of people with pacemakers living on boats suffering no ill affects.
Maybe the owners friends get sea sick very easily.
If you are that worried about it, start looking at other boats or consider a RV.
Didn't know that RVs float?
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Old 06-29-2020, 07:48 PM   #11
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55’ with a beam of 15’ seems very narrow to me. I had a 46’ that had a beam of 16’ and it was very stable.
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Old 06-29-2020, 07:53 PM   #12
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If you are worried about the effects of EMR from your 12-volt batteries, I hope you are not using a cell phone, or even getting near to one.
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Old 06-29-2020, 08:37 PM   #13
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If you are worried about the effects of EMR from your 12-volt batteries, I hope you are not using a cell phone, or even getting near to one.
Not really sure, but feel reasured that most people think it's not an issue.
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Old 06-29-2020, 09:06 PM   #14
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At least you have a good operating manual that you can update based on your experience with the boat.

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Old 06-29-2020, 09:50 PM   #15
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If the boat ever turned turtle and insurance found this thread, would they pay up?

Keep looking, plenty of other boats out there without stability agenda to be concerned about.
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Old 06-29-2020, 09:57 PM   #16
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=GoneFarrell;894447Keep looking, plenty of other boats out there without stability agenda to be concerned about.
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Old 06-29-2020, 09:58 PM   #17
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People have been getting sea sick long before batteries were invented.
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Old 06-29-2020, 10:16 PM   #18
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55’ with a beam of 15’ seems very narrow to me. I had a 46’ that had a beam of 16’ and it was very stable.
My boat is stable, and has length of 50' and beam of 15'6". I don't see the length to beam ratio of the boat in question being unusual.

I have Naiad's and they keep the boat flat underway in most conditions. If they are sized appropriately and operating then no-one should get seasick underway.

At anchor it sounds like flopper stoppers are needed. I'll also be adding those before my next Great Barrier Reef trip where you often find yourself trying to anchor in adverse conditions. eg wind at 90° to tidal current, waves from 15-20kn winds topping the reef at high tide and generating roll for a few hours.

The tank balancing & loading regime, together with an apparent tendency to make crew seasick, heavy steel superstructure, and existence of a stability report all suggest to me that the boat needs a bunch of ballast. Was ballast removed by someone at some point? Best to get an NA to use the stability report, plus further tests if required (eg inclining test), to get that sorted as to how much ballast and where. It might not cost that much to do.
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Old 06-29-2020, 10:54 PM   #19
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My boat is stable, and has length of 50' and beam of 15'6". I don't see the length to beam ratio of the boat in question being unusual.

I have Naiad's and they keep the boat flat underway in most conditions. If they are sized appropriately and operating then no-one should get seasick underway.

At anchor it sounds like flopper stoppers are needed. I'll also be adding those before my next Great Barrier Reef trip where you often find yourself trying to anchor in adverse conditions. eg wind at 90° to tidal current, waves from 15-20kn winds topping the reef at high tide and generating roll for a few hours.

The tank balancing & loading regime, together with an apparent tendency to make crew seasick, heavy steel superstructure, and existence of a stability report all suggest to me that the boat needs a bunch of ballast. Was ballast removed by someone at some point? Best to get an NA to use the stability report, plus further tests if required (eg inclining test), to get that sorted as to how much ballast and where. It might not cost that much to do.
Ballast is apparently there. Full oil filled keel with added lead ballast.
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Old 06-29-2020, 10:56 PM   #20
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I see many steel boats with aluminium super structure. Must be because they're trying to lower center of gravity to increase stability.
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