Light electrical tingle when touching boom

[RS_Grampian]

On a few occasions -- not always -- I've felt a slight electrical tingle when running my hand along the boom as I work my way across the cabin top. It happens when the sail cover is still on; typically when I first get onto the boat at the dock. I don't ever recall feeling it when touching the boom directly, when away from the dock, or when putting the cover back on and leaving the boat. Is this something I should be concerned about? Here are a few more details about my setup:

The boat has 2 batteries, 1 house and 1 starter; they're wired via a add-a-battery switch. I feel the tingle when getting on the boat and the switch is set to off. The system is NOT grounded to the keel.

There is no shorepower to my boat (nor is it wired for it). Most of my neighbor's boats are hooked up for power.

The boat has an outboard; it's always fully out of the water when not in use. The boat has a lead keel but other than that I don't know of a metal to water contact. There are thru-hull transducers for speed and depth, plus a newer shoot-thru transducer in the stern.

There's a small 5W rated solar panel on the stern rail to trickle charge the batteries.

My 12V system is mostly new, robust, and as far as I know working properly.

Could the mast/rigging just be picking up a little stray charge from the air?

Anyone ever heard of anything like this, and is there a solution or it even worth worrying about? Maybe it's just some static I'm brining on board when I first get to the boat?

 

[RobertLangdirect]

Wow. So, unless your boat is metal, or you are touching metal, or the rain just fell and you are barefooted and sprinklng salt, there should be no way for a fiberglass or wood hull to complete a circuit to shock you. Even static needs to run to ground. Tell us again in more detail where you are and what you are touching or standing on.

 

[tommays]

Sail cover could definitely do a static tingle and the same thing if my boat has blue plastic traps over it

A section of are dock ramp is plastic lumber and no matter how or what kind of shoe you have a trip across it results in a shock 100% of the time

REAL BAD STUFF FOR A GAS DOCK

And how often do you get a static shock from a car sitting on rubber tires

 

[walt]

This does sound like normal old static electricity.. However there is another "corona current" model based on charged thunderstorm clouds that could also explain that.

All that negative charge in thunderstorm type of cloud will produce an electric field. Assuming that the mast and the boom are not electrically connected to anything grounding them to the water surface, any sort of sharp point at the top of the mast can develop corona current due to the electric field produced by the cloud. The sharp point causes electrons to be "ripped" from air atoms leaving behind a positive air ion that floats away in the wind. The electron goes to the mast. The mast looks like a capacitor to the water surface and when you add electrons to it, a voltage is created depending on how much charge is added and the capacitance of the mast.

Even after the cloud is gone, if the mast is well insulated, its "capacitance" can hold that charge probably for some time. Probably not days but maybe hours at least.

When you come along, you are at ground potential and also have a capacitance to ground. Since the mast is charged up and at some higher negative potential and you are at ground, charge can flow from the charged capacitor (mast) to the uncharged capacitor (you). You wouldn’t need to be directly touching the metal for this charge transfer to occur but you would probably need to get fairly close to the charged metal. This model would likely only produce one single shock. However, if the storm clouds were still around the the field was strong, you could get shocked multiple times.

 

[justsomeguy]

As Walt explained, surrounding thunderstorms can have some potential.
I've experienced some remarkable electrical discharges touching the radio, winch handle, outboard motor and the shrouds when the mast was up, but the boat was on the trailer. Arcs of about 3/4 of an inch!

But these discharges didn't really "tingle", they snapped.

 

[Chris Burti]

'lectricity is funny stuff... what you describe sounds an awful lot like what stray AC current feels like which can be real hazard in marinas. One hypothesis is suggested by the circuit that would result if your bilge is wet, your bilge pump ground wire is exposed, all of you common wiring is connected to a buss and any of your mast electrical fixtures are grounded to the mast. everything would work just fine, but if your neighbor has a faullty ground on their shore power system, you could feel a tingle when close to the boom....

 

[kenn]

[edit] ahem. Never mind. [/edit]

 

[captcoho]

Anyone who's used an old tube guitar or P.A. amp with a ground problem will know that the AC can give a steady tingle, which is different from the feel or snap of static electricity. Such a potential is usually measurable with a digital meter on the AC volts setting, with probes between the source and AC ground or water-pipe ground.

So to the OP - if you feel this tingle only at a marina and it's repeatable, it's possible there's an AC-related problem. When you feel it, the first thing to try is to disconnect your shore-power cord and see if that made a difference.

Did you read the post???
No shorepower.....

 

[kenn]

Did you read the post???
No shorepower.....

You're right. Sorry.

 

[RS_Grampian]

Thanks for the replies, everyone. I'm going to have to start making a better mental inventory of the conditions when it happens again (meteorological conditions, if I'm barefoot or wearing shoes, if I ever still feel it once the sail-cover is removed, etc.)

Looking back on the 2 or 3 times that it did occur, I think it just happened when I first got on the boat and walked from the bow to the cockpit. My sunbrella sailcover is new last fall and was treated with a water-repellent (a Star-Brite product, if memory serves me). I kind of think that once I felt it on each visit that was it, then no more... and it was a continuous tingle, not a snap. It's only happened this spring, when the air was presumably drier. Also, if it makes any difference, I have the shortest mast on the dock.

Taking the above suggestions, too, I'm going to have to look to see if there are any exposed wire connectors down in the bilge leading to the pump. It's always bone dry, but maybe there's a little flaw in the wiring that's close to the keel or a keel bolt.

Again, thanks for the insights and wisdom.

 

[brazenarticle]

Sailing gives me the tingles too!

"If it doesn't kill you it makes your stronger" and "If it ain't broke don't fix it". Sailboats and sailing are supposed to give you a tingle. Some feel it when winning a race, others when the perfect coat of varnish dries perfectly.
Lucky you - just touching your sail cover reignites the spark. Thats not a problem, it is a feature! Picture the popularity of the skipper anywhere who can say "run your hand over my boom, feel the spark".
You sir have discovered sailing viagra. If after touching the boom repeatedly your hair grows back, paunch disappears and money appears in your bank account will you still be looking for a "fix"?
Ye gads man, you are looking a gift horse in the mouth! Who made that sail cover? I need one!

 

[jibes138]

Low voltages shouldn't give you a tingle. In other words take a AA battery and put a finger on each end...feel anything? Now grab the battery posts of a 12 volt battery..feel anything? So if you are not just getting a shock from static jumping suddenly to ground and getting a continuing tingle it is likely higher voltage. The stray current from AC on another boat sounds like the most plausible but perhaps some EE's on here would be better qualified to comment. Is your mast keel stepped and thus making a circuit to the water?

 

[RS_Grampian]

Low voltages shouldn't give you a tingle. In other words take a AA battery and put a finger on each end...feel anything? Now grab the battery posts of a 12 volt battery..feel anything? So if you are not just getting a shock from static jumping suddenly to ground and getting a continuing tingle it is likely higher voltage. The stray current from AC on another boat sounds like the most plausible but perhaps some EE's on here would be better qualified to comment. Is your mast keel stepped and thus making a circuit to the water?

No, the mast is stepped on the cabin top. I don't think any of the shrouds or stays extend through any metal to the waterline. All I can think if is the wiring in the mast for the lights and a defunct antenna that may conceivably lead back through the boat.

 

[RS_Grampian]

"If it doesn't kill you it makes your stronger" and "If it ain't broke don't fix it". Sailboats and sailing are supposed to give you a tingle. Some feel it when winning a race, others when the perfect coat of varnish dries perfectly.
Lucky you - just touching your sail cover reignites the spark. Thats not a problem, it is a feature! Picture the popularity of the skipper anywhere who can say "run your hand over my boom, feel the spark".
You sir have discovered sailing viagra. If after touching the boom repeatedly your hair grows back, paunch disappears and money appears in your bank account will you still be looking for a "fix"?
Ye gads man, you are looking a gift horse in the mouth! Who made that sail cover? I need one!

lol.. I made the sailcover myself from a SailRite kit. Want to buy it? ;-)

 

[jibes138]

Sometimes the mast is grounded for lightning protection. On a deck stepped mast it could be the plate on the deck or you might have a ground wire attached to a chain plate. The lights on your mast are 12 Volt so you shouldn't get a jolt from that. If you are in fresh water don't go swimming until you know for sure, many deaths from stray current in marinas.

 

[Ray Bowles]

RS, Do you recieve the same feeling when away from the dock. I was wondering if you took the boat out away from the dock and other boats if the problem is still there. I would leave the boat configred exactly as it is at the slip. Sails down, sail cover on etc. That would let you know if it is your boat or something bleeding over from another boat.
Please let us know what you find.
Good Luck, Ray

 

[tkanzler]

If it were me, I'd check the power cords to the nearest neighbors' boats with a clamp-on ammeter. If one is leaking to the water, you'll register current on the ammeter, unless it's so small the meter won't show it (like analog without a low enough range). If not, you'll read zero current, even if it has a ground fault that's not passing through the water back to the transformer. You may have to check a number of times, as equipment cycling on and off may make it a hit or miss situation, and a negative at any given time doesn't mean you won't read a positive at some other time, but a positive at any time is not good. It may or may not have anything to do with what you experience, but it costs nothing, takes only a few minutes, and I'd want to know regardless.

 

[Sumner]

As Walt explained, surrounding thunderstorms can have some potential.
I've experienced some remarkable electrical discharges touching the radio, winch handle, outboard motor and the shrouds when the mast was up, but the boat was on the trailer. Arcs of about 3/4 of an inch!

But these discharges didn't really "tingle", they snapped.

Same here working on the boat at home when a storm is passing nearby. The first time I kept hearing a snap every few seconds and there was a spark jumping from the metal trim on the rubrail to the step ladder next to the boat. I also got zapped a couple times. Now I have a metal rod driven down in the ground next to where I work on the boat and when a storm is near I connect a jumper cable from the metal on the boat to the rod. I also usually quit working on it and go inside.

I think it is caused by what Walt was referring to,

Sum

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